# Looking for a low windage, low maintenance, simple electrical system solution



## chrisncate (Jan 29, 2010)

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## btrayfors (Aug 25, 2006)

What are your cruising plans? What area?

Will you spend most of the time at anchor? In a marina with shorepower?

Solar is much lower maintenance than any other solution. Panels can be mounted above the bimini and, with a good MPPT controller, will put out reliable power.

However, you really need to do an estimate of your daily power consumption. Use one of those MacBooks to figure it out (with a spreadsheet).

You didn't mention refrigeration.

From what you described, sounds like about 100 amp hours to me, so you'd want to have a system capable of regularly delivering that much power.

RE: batteries, you'd want a minimum of 300AH capacity if you're regularly using 100AH per day.

Bill


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## Izzy1414 (Apr 14, 2007)

Ditch the macbook requirement, Chris. Give yourself (and us) a break, at least while you're out there sailing.


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## GaryHLucas (Mar 24, 2008)

Izzy1414 said:


> Ditch the macbook requirement, Chris. Give yourself (and us) a break, at least while you're out there sailing.


Sounds to me like this guy is working with his Mac Books and phones, and you want him to be unemployed too?

Gary H. Lucas


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## tdw (Oct 2, 2006)

Methinks yon Izzy taketh the piss !! 

I was also going to ask about refrigeration. No mention of it on your site Chris. If you do intend having refrigeration it makes a huge difference to your power bill. 

I'm not questioning your decision but why do you need the two MacBooks ? If you could get away with only the one, again a big saving in power. Same goes for phones to some extent. 

Right now you have one 80w panel, correct ? Either you are going to have to double that or get a wind generator, maybe even both. Do as Bill says and make up that spreadsheet. You are going to have to get this right cos without that engine there is no quick top up available to you.


ps - pics on your site show pressure water .. you sticking with that or going manual ? What if anything are you doing for hot water ?

pps - not on the power consumption subject but is that really a non gimballed stove ?


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## Izzy1414 (Apr 14, 2007)

Hehe, I was only being partly facetious .... the (and us) part.  The computers and phones do add to (complicate) Chris' requirements significantly enough to question how much he needs those trappings of society on a vessel that most of us use to escape said trappings ..... OK, I've made my practical point, now I'll step down from my soapbox. Carry on ...


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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## mitiempo (Sep 19, 2008)

You should have a battery bank capable of supplying lasting 2 days without charging as a minimum, maybe 3 days. Only half of your AH are usable. If your daily usage is 100 AH, that means a 400 to 600 AH battery bank giving you 200 ti 300 AH usable. 
The best affordable way to achieve this and end up with a long lasting durable bank is with golf cart batteries. 4 6 volt in series/parallel will give you a 450 AH bank, 6 will give a bank of 675 AH.

Solar is the low maintenance quiet solution. You don't say where you are going to be which will make a difference. In a climate like Florida 2 135 watt panels should almost give you 100 AH per day based on 5 hours at full output. 
Someone with real world solar experience may post the real numbers.

If you bought one netbook and saved the Macbooks for when on shorepower it would make a huge difference to the energy budget.


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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## mitiempo (Sep 19, 2008)

Series will double voltage. Parallel doubles AH. Golf cart batteries are about 225 AH @ 6 volts. Series 2 and you have 225 AH @ 12 volts. Series 2 pair and then parallel those to get 450 AH @ 12 volts. Parallel another pair already in series and you have 675 AH @ 12 volts. 

But will you be on a mooring all the time or at a dock with shorepower? 

You have to determine your daily expected AH usage by finding amperage of each item x number of hours each is used. For example if your stereo uses 2 amps x 7 hours that is 14 AH. Your lights being led are low draw but the Macbooks are the heavy draw. I would think an efficient refrigeration system would not use more AH in 24 hours than the laptops.

If you stay up north you will not get the approx 100 AH per day I suggested you could possibly achieve in a place like Florida with 2 135 watt panels, which are about 2' x 4' each.


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## tdw (Oct 2, 2006)

OK, so I see that CnC need the Macs for work. Thats a fair cop. No refigeration saves lots of energy. 

Brian, Chris says they will be in the Chesapeake to begin with and then down south to Florida. From memory reading the blog, long term goal is South Pacific. 

Chris, that 135w panel (sorry I thought I read 80w in the blog) is surely going to be a minimum and I reckon you'll be needing the wind generator as well. We've got two 80w panels and even with that I reckon we'll still be running the engine an hour a day. (No wind generator, wish I had one). We do have refrigeration (small 12v job), music machine runs a couple of hours a day, lights gradually changing to LED but still some halogen. We only have two 105ah for house, intend to add one more.


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## chrisncate (Jan 29, 2010)

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## tdw (Oct 2, 2006)

Chris,
While there will be an obvious effect caused by the gear reality is that you will have to simply learn to live with it. I'm presuming you will be adding a dodger and bimini ? They will have pretty much the same effect as a couple of panels. 
My attitude is that you are a cruising boat. You will never be as sleak as a pure racer. The practicalities of cruising rear their heads (ugly or not ) and have to be dealt with. 

btw ... there is of course such a thing as a towable generator. I don't know much about them at all but if I remember rightly SimonV used one on his trip back to Australia a few years back. Apparently wee fanged beasties like to eat them but at least they don't create windage. 
I have zero experience with wind generators but I'm guessing they are more an issue of weight than windage.


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## Izzy1414 (Apr 14, 2007)

tdw said:


> I have zero experience with wind generators but I'm guessing they are more an issue of weight than windage.


The ones I've been around have been unbelievably obnoxious as well ..... the noise that is. Might just be me, though. And I watched one slice an expensive lure right off my brother-in-law's fishing pole .... that was high entertainment. As you say though, Fuzzy, you're a cruiser and ya gotta make compromises and get used to some things you don't necessarily like.


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## mitiempo (Sep 19, 2008)

Sorry, I missed the post that stated the Chesapeake was the cruising area for now.

Chris 

You can't re;y om the panels giving their rated output every day/ You need to have a large enough bank to survive a day or two without much charging. Then you need to have enough panels to maximize charging when conditions are good. I think 2 panels the size of the one you already have (130 watts each) or at a minimum 2 80 watt panels are required, as well as a battery bank of about 400 AH or more.

Towed gens are ok as far as they go, but if you're not moving they are not charging.
Wind generators are viable in addition to the panels. The problem with these is making space for the mount. It has to be high enough that you can't walk into the blades. I helped install a Superwind 350 on a Westsail 32 a few months ago. Blade diameter is just over 4' and to be safe the pole is 9', allowing just under 7' clear under the blades. A pole that tall has to be well attached and solid otherwise vibration will shake things. In this case we had a custom pole made od heavy wall stainless pipe and hand polished. You can't get polished heavy wall, only light tube. The other problem is the wind gen itself. The one we installed is the only one I have ever seen that is quiet enough that I would be happy. In 10 to 15 knots of breeze you can't hear it and putting your hand on the pole there is no vibration at all. Between gen and pole the cost was over 4k. You do get what you pay for and can buy peace and quiet.

There is a bonus though - you don't need a separate starting battery.


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## LakeSuperiorGeezer (Oct 8, 2010)

*Parallel Batteries*



chrisncate said:


> Won't series NOT increase the amp hours? I thought parallel only increased the amp hours?


You are correct. Putting the batteries in series doubles the voltage, not the amps.


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## BELLATRIX1965 (Jan 2, 2007)

Another plus for solar: In my somewhat limited experience in the Chesapeake, you can go for days with little wind (summer) - seems like you have a better chance of good sun charging your batteries vs. relying on wind? Here in Maine, it's the other way 'round!


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## Ajax_MD (Nov 24, 2009)

I think your refusal to install an engine, your refusal to mount the necessary panels and wind turbines coupled with your high energy budget is unrealistic.

If you consult the Chesapeake Bay PHRF list, you'll note that Alberg 30's are slow, and actually rate even slower than my Coronado 25. 

Putting up the panels and a wind turbine aren't going to make it much worse. If it really weighs on your mind, use quick-disconnect electrical and mechanical fittings so that you can take them down and stow them below if you feel that they're slowing you down.

Or face the reality of your energy-intensive mode of employment and install an engine. Whichever.


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## LakeSuperiorGeezer (Oct 8, 2010)

*Wind Shadows*



BELLATRIX1965 said:


> Another plus for solar: In my somewhat limited experience in the Chesapeake, you can go for days with little wind (summer) - seems like you have a better chance of good sun charging your batteries vs. relying on wind? Here in Maine, it's the other way 'round!


Also, consider wind shadow. Buildings, rigging for other boats, trees, etc will decrease the wind. This is important because if you double the wind speed, you get about four times the electricity.


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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## mitiempo (Sep 19, 2008)

Without the Macbooks you could get by with only one panel. But I would still use 4 6 volt golf carts for a bank of 450 AH. It gives you reserve capacity.

Best way to mount the panels? On an arch at the transom or poles like these:
Atom Voyages | Voyages Aboard the Sailboat Atom - The Atom SolarTracker adjustable solar panel mounts for sailboats


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## AdamLein (Nov 6, 2007)

Chris, assuming you're mounting your panel horizontally, the windage should not be very great. Of course, when the boat is heeled, the panel is longer horizontal, and it's in such situations that you care most about windage. How much do you expect to be heeled over? At 20 degrees, one square inch of panel diagonal is 0.34 square inches of windage (approximately proportional to the sine of the angle of heel). A 120W panel is 1600 sq-inches, so that's 540 sq-inches of windage, about a third of my mast's windage. Of course it's not as bad as spars and things, because it's at quite a slope, so it won't hurt you as much. I suspect very little.

Maybe MaineSail can do a wind tunnel test on windage due to solar panel at various angles of heel.

Anyway, are you adding a hard dodger of any kind? You can mount your panels on that and then you're not significantly altering the windage. You could probably build something around/beside your windvane to mount panels on, but stuff mounted on the transom tends to get damaged in rough weather I hear.

As for your energy needs, a laundry list of equipment does not an energy budget make. Maybe instead of asking how much panel you should by, figure out how much panel you can install, and then see how much power you can afford to consume on a daily basis.

Here's a quick description of what I did (because I was bored, not because I'm in your situation):

1) Make an energy budget. That's a spreadsheet with your items down the first column, their draw in amps down the second column, and the hours per day that you spend using each one down the third column. The fourth column has the product of the second and third columns. 

If you have different energy expenditure "regimes", you can repeat the third and fourth columns many times; once for "passage making", once for "weeks at anchor", once for "at the dock", whatever. Your behaviors and equipment demands will obviously be different in those circumstances.

2) For each regime, sum up your daily amp-hour draw. I also added a 10% fudge factor at this point. Put this below the last item.

3) Next work out what you get from your panels/turbines/etc. For me it's just panels, so I put rated wattage W, then charging voltage V (not 12), then effective hours/day H of performance at rated output; the daily output of my panels is H * W / V.

4) Result from step 3 - result from step 2 = daily amp-hour surplus. This could be positive or negative. If it's positive, good for you.

5) If it's negative, your next task is to figure out how many days you can stay off grid in each of your regimes. Take your house bank capacity in Ah, and set a safety factor equal to the fraction you'd be willing to draw (say, 40% of total capacity). The product is your effective battery capacity. Divide that by the result from step 4 to get the number of days before you need to go find find a power outlet.

If your goal is to be off-grid and self-reliant, I think the result from step 5 is a good metric for how well you're doing at that.

If you'd like, I could send you the spreadsheet I created to do this. It's fairly humble compared to your plans, as I'm just daysailing/weekending, but you should be able to expand it to cover your needs.


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## jrd22 (Nov 14, 2000)

Chris- do you have Calder's book on electrical? If not, get it. You will be able to figure out your daily amp hour consumption and design your charging system all by yourself (self reliant). As someone else said, you are being unrealistic expecting to charge your laptops, phones, lights, etc. on a year round basis in the Chessy area with a small battery bank and minimal panels and no engine charging (what are you planning for heat during winter, and fans during the summer?). What I hear you saying is that you would like technology to bridge the gap between what is possible and what you want, some compromises may be necessary.


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## LakeSuperiorGeezer (Oct 8, 2010)

Take a look at the label on the computer and see how much power it uses. Most laptop computers use about 30 watts. The MacBook has a built-in 63.5-watt-hour lithium-polymer battery that lasts up to 7 hours so figure 9 watts. (About 6 watts per 24 hours average for two computers) Use the MacBook for listening to music through external speakers or headphones. Fans use about one amp each so that's 24 watts for two figuring two at night for berths and two in the cabin for day use. Say 2 watts for focused LED lighting, for 16 hours per day is 1.3 watts average in 24 hours. One watt for anchor light, and ignore cell phone as too small to matter. This is about 33 watts at anchor. The total is 66 amp-hours per day where you divide 33 watts by 12 volts to get amps and multiply by 24 hours.

The following is from FirstStar LED Four watts is used for masthead light and if used 16 hours of 24 hours day in winter this gives 3 watts average in 24 hours. No running lights since no engine. Go with two of the focused 1 watt 12 volt LED 16 hours per day for reading. Consider red LED for navigation station to preserve night vision. Total is near 5 watts average in 24 hours, if the boat has ventilation while underway so no fans. This calculates to 10 amp-hours per 24 hours.

If you want some navigation electronics, figure one computer underway for navigation at 9 watts, GPS (negligible watts), a depth sounder (2 watts) and AIS VHF (2 watts) radio as a minimum. The total is 13 watts average in 24 hours or another 26 amp-hours.

So you need approximately 36 amp-hours per day whether at anchor or sailing. You have a 135 watt solar panel good for about 6 hours per day because of sun angle, night time. Take 135 watts and divide by 17 volts (dropped to 14 volts for regulated charge) to get 7.9 amps and multiply by six hours per day, which gives you 48 amp-hours in 24 hours. However, since you only get about 80% amp-hours out of a battery that you put into it (entropy), one 135 watt panel is barely enough. You do not want to charge at more than 10 amps so looks like a 100 amp-hour battery will do it, and a single 27 group size marine battery will be required. However, you do not want to draw the batteries down more than 50% as batteries will last half as long because of shorted cells, you will need two panels and two batteries, and besides you should have some reserve if you use more power than you think you will. One of these or something like it is also needed:  Detailed Specifications for 6 Position-Slate Gray - PN 8053 - Blue Sea Systems. You will also need a charge controller for the solar panels. If you want a battery charger, get only one used for marine service like the following: HQ Series Battery Chargers HQ Series Battery Chargers builds battery chargers that will not cause electrolysis that can also use 240 volt 50 Hz input for over seas power grid. Their chargers are built to the Rules of the American Bureau of Shipping (ABS). These chargers are built like an isolation transformer in that the primary and secondary windings are separate.


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## catamount (Sep 8, 2002)

(1) as others have said, you really need to do your own spreadsheet of amperage draw for each appliance/fixture/use and estimated hours or use per day for each item on the list, so that you can calculate your total daily amp-hour demand. Consider two scenarios, at anchor vs. underway. Certainly there are examples out there, and the 100 amp-hour/day figure is a good starting point, but YOU need to do your own energy assessment. This is a really important exercise for understanding what the big consumers are and how to minimize your needs. Only you can estimate your uses!

(2) Look into getting DC-to-DC voltage converters to power your MacBooks. It's a bit hard because Apple will not license the mag-safe connector, but there is "MacGyver" -- they'll take your existing power brick, cut off the magsafe connector and marry it to a DC-DC converter (they have some other options, too). You will find the macbooks, powered through the AC-DC power brick which in turn is powered by a DC-AC inverter to be a really big energy hog (4 to 5 amps!), even if you keep the hard disk spun down, the screen on minimum brightness, put the computer to sleep at a minimum of non use, etc... WiFi is a big power user with the MacBooks, too, so think about how you are going to be connected to the network and what the energy demands are there.

(2a) similarly, get the car chargers for you phones rather than plugging AC charger bricks into an inverter.

(3) Whatever charging systems you end up with, you definitely need to get a decent battery monitor (e.g. Victron or similar) that can keep track of what is going in and out of your storage battery. Very very important!

(4) Have you considered the idea of a small Honda generator?


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## MarkofSeaLife (Nov 7, 2010)

I can't really help you because I dont know your area or your reall electricity needs. But I can mention this:

Wind generators lose friends. Try to have a solution where you don't become the boat people try to avoid. That being said lots have wind generators. They must be human, but as I never talk to them or anchor near them they may be from up some Sputnik.

Solar panels for a boat are good becuse theres no moving parts and theres only one or 2 places for corrosion to dig its lil claws into (the connections)

A BIG solar panel shoud have you happy. I have 2 x 120 watt pannels rail mounted on my 39 footer.

damn bliss man!  But 2 may be too big for a 30 footer.


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## LandLocked66c (Dec 5, 2009)

Good stuff in this thread!

Sounds like you need one more panel and you should have enough power to work with. 

You can lock the wind generator if the noise is too much, right?


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## MarkofSeaLife (Nov 7, 2010)

LandLocked66c said:


> You can lock the wind generator if the noise is too much, right?


Yes. But no one does. 

The comment most make to me is "we turn it off when we have guests aboard"

Then they invite us for drinks etc and they never turn the damn things off! So instead of being on the other side of the anchorage we are trying to slurp their beer 2 feet from the roarin' monster!!

At least its_ their_ beer!


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## mitiempo (Sep 19, 2008)

As I posted above you can get a quiet wind generator but the price will be high.

Solar panels are the ideal solution. But there will be days without much sun. That is where the larger battery bank comes in - it can give you a few days of use at whatever your normal usage is when the panels are idling under clouds. When it rains or snows solar panels are of little use.

Definitely get a good battery monitor like the Victron BMV-600 ($158 @ Jamestown Distributors). You will never know the state of your batteries without one.

As far as a battery charger, there are other options besides the Charles, which are a bit expensive. Xantrex or Iota make good 3 stage chargers that will take good care of your batteries when plugged in. As far as I know any good marine charger keeps the AC and DC separate. But it really makes no difference as the DC ground and the AC ground should be connected anyway - both for safety and to satisfy ABYC regs.

As posted by Catamount the best way to power a laptop is not through an inverter.


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## LakeSuperiorGeezer (Oct 8, 2010)

mitiempo said:


> Solar panels are the ideal solution. But there will be days without much sun...
> As posted by Catamount the best way to power a laptop is not through an inverter.


At least with rain and snow, the fans are not drawing power for cooling.


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## LakeSuperiorGeezer (Oct 8, 2010)

You could get by without the battery monitor by using a hydrometer. This will tell how much amp hours are in the battery, but you have to use a little care because you are handling 32% surfuric acid, which is Hard on clothes and skin.


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## mitiempo (Sep 19, 2008)

There is no comparison between getting out the hydrometer to check the specific gravity of the batteries and pushing the button on a conveniently installed battery monitor.


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## Faster (Sep 13, 2005)

mitiempo said:


> As posted by Catamount the best way to power a laptop is not through an inverter.


Running a Toshiba laptop last summer through one of those small 75 Watt lighter-plug inverters was using between 4-5 amps according to my Link10. As continuous duty that's as much as my fridge!


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## LakeSuperiorGeezer (Oct 8, 2010)

*Comparison*



mitiempo said:


> There is no comparison between getting out the hydrometer to check the specific gravity of the batteries and pushing the button on a conveniently installed battery monitor.


Well it is cheaper Amazon.com: Dorman 9-1302 Hydrometer: Automotive


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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## catamount (Sep 8, 2002)

LakeSuperiorGeezer said:


> You could get by without the battery monitor by using a hydrometer. This will tell how much amp hours are in the battery, but you have to use a little care because you are handling 32% surfuric acid, which is Hard on clothes and skin.


The hydrometer only works with flooded wet-cell batteries, and I agree with miitempo, really there is no comparison to an integrating ammmeter (aka battery monitor) for understanding what is going into and out of your battery -- in other words, a battery monitor can tell you a lot more than just what the current state of charge is.


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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## chrisncate (Jan 29, 2010)

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## catamount (Sep 8, 2002)

chrisncate said:


> Also, many of my questions center on wondering what brands are better than others, people personal experiences, real life set ups that people might have and can recommend or not recommend, etc.


OK, here's my real-life set-up. Note that I'm not a liveaboard like you apparently plan to be, rather I am a passage sailor (I do a lot of overnights), but otherwise my system might give you some ideas.

Underway, with out the computer, I am burning between 2.5 to 3 amps, or about 60 amp-hours per 24-hour day. This is supporting my sailing instruments, AIS transponder and Watchmate display, VHF radio with cockpit mic, autopilot, and at night, LED tricolor and compass lights, and occasional short use of a cabin light. I was surprised by how little juice the autopilot took, but my boat balances well.

I have a house battery bank of three Odyssey 31M-PC2150 "thin plate pure lead" AGM batteries with a total capacity of 300 amp-hours at 12 volts. These batteries have a higher charge acceptance rate than the usual flooded battery, so they recharge quickly if you have a big enough charging source -- but they are very sensitive to the charging voltages, so you absolutely must have decent voltage regulation set on the proper voltages for the different charge stages. They also are very sensitive to being fully charged up as often as you can.

To charge, I have an Amptech S125e alternator rated at 125 amps. This is quite a beast to power with a single 1/2" belt on my old 14-horsepower two cylinder diesel, but it works! The alternator is regulated by an external Sterling Power Advanced Alternator Regulator (customized to match the required voltage charging profiles for my batteries). This is augmented by a couple small solar panels (10 watts each) fed through a Genasun MPPT solar charge controller (customized to the required float voltage for my batteries). Finally, I have a ProMariner i1230 shore-power charger capable of running on 95 to 240 volts AC, 50 or 60 Hz (e.g. world-wide). I bought this charger before I bought the batteries, and if I had it to do over again, I would buy the 40 amp model (or even larger if they had it) because the Odyssey batteries really liked to be charged fast. Fortunately, the charging profile of this charger matches the requirements of the Odyssey batteries (very important). My monitor is a Xantrex XBM battery monitor, although the particular version I have has been discontinued. These days I would probably avoid Xantrex if you can find another option. FWIW, The batteries, alternator, regulator, and solar charge controller were all supplied by my friend Bruce Schwab of Bruce Schwab Rigging and Systems..

I have a separate Odyssey 34M-PC1500 battery for starting the engine, which is charged by a Xantrex Digital EchoCharge device whenever the voltage on the house side is high enough -- the engine electrical system and the house electrical system are otherwise totally separate (e.g if I wanted to use the house bank to start the engine, I would need jumper cables).

My solar panels don't make a huge contribution, but they do contribute some, especially now with the MPPT controller. They're really there just to keep the batteries topped up and maintain them in float voltage. They are portable panels that lay on top of the cabin house (companionway sea-hood), tied off to the hand-rails. When we are at anchor, I can move them around and prop them on the deck at different angles to maximize their energy capture. I can also remove them and stow them below if I think they are going to be in the way when we are sailing or in heavy weather. Eventually I will probably get some bigger panels, but I would make them easily de-mountable so that they're not in the way when we are sailing and don't present a liability in heavy weather (or cause excess windage drag in light air).


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## chrisncate (Jan 29, 2010)

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## catamount (Sep 8, 2002)

chrisncate said:


> How in the heck do you take away from everything I have written (not to mention my site, noted in my sig) that I plan to be a livaboard and not a passage sailor? Our entire reason for what we are doing is to go travel the world.
> 
> ?


The difference is I don't live and work on my boat -- I live and work on land. I really am only on my boat when I'm actually sailing it. You may be planning to make passages and sail the world, but most of the time you will likely be at anchor, and I presume living/working aboard. At least that's the sense I've been getting. My apologies if I am off-base.

I'm sorry to say that I haven't read your site.


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## chrisncate (Jan 29, 2010)

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## mitiempo (Sep 19, 2008)

Chris

You adjust the solar panels for maximum AH into your batteries - not for windage. You really can't afford to do anything else. Here's a link to a good easy to understand primer on solar power. 
Adrift at Sea » Solar Power on Boats

You realize you need a battery monitor - good.

If you treat solar as the only charging method when away from the dock and size it accordingly you will probably be ok. Wind gens are noisy - if you can hear another boat's wind gen they can hear and feel it more.


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## LakeSuperiorGeezer (Oct 8, 2010)

*Go With Two 135 Watt Panels*



chrisncate said:


> Excellent post, thank you. Very helpful. When you say my 135 watt panel will just barely be enough, would you recommend trying to cram another panel onboard somehow, or would you recommend a wind gen to supplement..
> 
> ?


I would go with another panel. Here is an example of a wind generator, not sure if it is typical: Wind Powered Generators and it cost $1500. There is also the cost of speed governor on the blades and mounting so maybe another $500. At 12 knots of wind it gives the same amp hours as the 135 watt panel. There is the noise issue. You need to check with the weather service to see what the prevailing wind velocity is for your area and how constant. Make sure there are no wind shadows from building, trees, and boats. The wind generator does give power 24 hours round the clock when there is wind.

A solar panel costs about $362 like this one, Kyocera KD135GX-LPU 135 Watt Solar Panels @ AltE Store, 1.8 x 26.3 x 59.1 inches. If you mounted horizontal above the cockpit floor and below the boom, would you have room to stand?

I am going by memory, but I think a solar panel gives half power on a cloudy day. You probably would not need the fans, well maybe in the summer, but then the days are longer and you will get more solar power with longer days anyway for running the fans. So, two panels would get the job done.


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## mitiempo (Sep 19, 2008)

For solar panels figure about 5 hours at full output per day when the sun shines, winter or summer.


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## chrisncate (Jan 29, 2010)

mitiempo said:


> Chris
> 
> You adjust the solar panels for maximum AH into your batteries - not for windage. You really can't afford to do anything else. Here's a link to a good easy to understand primer on solar power.
> Adrift at Sea » Solar Power on Boats
> ...


Well _duh_, I know you adjust the panels for optimal light... 

But... you _could_ also adjust them underway to minimize windage in a situation where you might want to milk that 1/4 extra knot of speed for some reason... just saying.. 

Sometimes I get the feeling some of you think I am _completely_ unaware..


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## mitiempo (Sep 19, 2008)

The panels are low on the boat, where the windage will have less effect. The panels will be horizontal for the most part, angling towards the sun to get a higher output on sunny days. 
I doubt you could get an extra 1/4 knot unless the panels were flat to the wind to start with. 

If you do not have either a noisy wind gen or a quiet very expensive wind gen and have no engine your options are limited. 

A large battery bank and 2 good size panels you can adjust for optimum output are your only choices. For the extra 1/4 knot, new well cut sails instead of the old baggy ones will make all the difference.


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## catamount (Sep 8, 2002)

A couple more thoughts, if I may -- going with solar as your primary source of charging, you will not be able to take advantage of batteries like my Odyssey's as you will not be able to generate the high amp charging currents they like. Rather you'll want a good true deep cycle battery that does best with slow charge rates. Nonetheless, I think you'll get better performance from your batteries if you pay attention to the charging profile specified by the battery's manufacturer and make sure that your charge regulators are set to the appropriate voltages.

Secondly, the wiring in your boat will make a difference in your energy needs. If you have long runs of under-sized, corroded old wire, with poor connections throughout, you will be wasting a lot energy to resistance-generated heat just if your wiring. Make sure your wiring is of sufficient size or oversize, that your runs are not overly long, and that all connections are well made and in pristine condition (and protected so that they'll stay that way).

Finally, while most of the discussion in this thread has been on the energy supply side, it is on the demand side where you can really make some gains. Energy conservation is not just about using more efficient fixtures and appliances, but also about using less of them, for less time. (As mentioned before, you really need your energy budget spreadsheet here to see where the most gains can be made.)

So CFL and LED lights (I like Alpenglow), but how many lights do you really need? How about using an oil lamp for ambience and heat, as well as light, in the colder seasons?

Fans (I like Caframo Bora)? Again how many fans do you really need? Pay some attention to the boat's natural ventilation system -- input and output vents, hatches, and ports -- combined with windscoops, as well as the use of shade awnings, choosing paint colors appropriately, and maybe installing insulation (keeps heat out in the summer as well as in in the winter).

BTW, the power adapters for your MacBooks that I was talking about are available here -- http://mikegyver.com/


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## tommays (Sep 9, 2008)

Having a somewhat speedy J24 and a somewhat slow Cal 29 who's PHRF numbers are not that far apart unless you hang the panels like barn doors there just not gonna make that much difference 

The J24s real speed advantage comes from making much better VMG because it can point so much higher and has to make far less tacks not that its all that much faster


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## LakeSuperiorGeezer (Oct 8, 2010)

*Human Power Generator*

Human Power Generator: Bike Power, Human Power Generation from Windstream Power


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## LakeSuperiorGeezer (Oct 8, 2010)

Better check with Cate about the noise. It is my personal experience that women are much more sensitive to noise and odors than men are. (puts on asbestos suit)


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## LakeSuperiorGeezer (Oct 8, 2010)

If the wind generator is in use while under sail, it will slow the boat unless you are going down wind and then maybe not much power from the wind generator.


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## AdamLein (Nov 6, 2007)

LakeSuperiorGeezer said:


> If the wind generator is in use while under sail, it will slow the boat unless you are going down wind and then maybe not much power from the wind generator.


They need at least five knots to start spinning. If you're going upwind, they're slowing the boat down whether they're running or not. Which is worse is the same debate as fixed vs. freewheeling prop


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## LandLocked66c (Dec 5, 2009)

Chris didn't you guys already buy a wind generator? What are the reviews on them, noise wise... Perhaps there are some other owners that could chime in on said brand.


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## chrisncate (Jan 29, 2010)

...


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## chrisncate (Jan 29, 2010)

...


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## tdw (Oct 2, 2006)

Chris,
The only thing that really worries me is that you end up with only one power source. A succession of gloomy days could well leave you flat and you are relying on those Macs to earn a living. Still and all this is a work in progress and you'll have plenty of time before you set sail to work out whether solar alone will do the job.

Re "Liveaboard". Its a shame that the word has such negative connotations isn't it ? Shouldn't be that way but sadly the number of boats that end up as marina locked floating condaminiums have left the word with a tarnished image.


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## chrisncate (Jan 29, 2010)

...


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## scraph (Oct 19, 2009)

Well, I am a live aboard. I am in the Navy and they move me around quite often. Taking the boat from place to place for living vice another bare-walled apartment for six months at a time provides me some semblance of 'home'. I don't have the luxury of cruising around the world on my sailboat ... I do that on my submarine ... so I would prefer not to be ascribed a negative moniker because I still work for a living. But I digress...

To comment on measuring power requirements of equipment based on reading labels ... I don't recommend it. I have a lamp with a 10W bulb installed. I might be lead to believe that it will draw 10W / 14.1V = 0.7A. I measured it directly as 0.425A (which math calls 6W). I measured the power requirements of my stereo directly, at 50% volume, as 0.250A.

Powering a 17" laptop through a 400W inverter was drawing 1A. The specifications for that laptop claim 65W power requirement. The 65W power requirement is not something I will ever see during usage of the laptop while underway. I don't anticipate burning a DVD while playing a 3D-game and defragmenting the hard drive concurrently. So ... allowing for 65W power consumption of this laptop instead of worst case 20W is unrealistic and overly restrictive.

I have a Caframo Sirocco fan that has reported current draw of 0.25A (fast), 0.20A (med), 0.1A (slow) but I actually measured 0.20A, 0.16A, 0.12A, respectively.

My Lowrance LMS-525C df chartplotter (to include supporting NMEA 2000 network, depth transducer, NMEA 0183->2000 bridge, NMEA 0183 multiplexer, etc) draws 0.5A (7W) while operating though the reported 375W rms of the depth transducer alone might lead you to expect otherwise.

I wouldn't recommend simply reading the labels or specs sheets as far as power requirements because, in my experience, they aren't very accurate and adding a 'fudge' factor on top of them takes is like putting lipstick on a pig. The number you are adding a fudge factor to may not be very representative in the first place.

The method I used to measure was by using a multimeter (in ammeter mode). I pulled out the DC switchboard to gain access to the back, removed the supply cable, and temporarily wired the ammeter in series. All the breakers were open, all loads were turned off, and I energized them one at a time to determine individual current requirements. For lights, I recommend allowing them to warm-up before recording power requirements (current should stabilize shortly). For pumps, power requirements should be measured with the pump fully primed (a bilge pump on an empty bilge does not draw as much power as a fully primed bilge pump, for example). For other sorts of loads (stereos, laptops, chargers, etc) measure their power requirements during normal operating conditions (ie, stereo volume at listening level, laptop performing tasks that you use it for, chargers running on a low battery and not a fully charged battery).

As far as power generation ... I'd recommend taking a look at Aquair 100 (http://www.wire-wiz.com/catalog/c21_p1.html). It is a tow water generator that can be easily converted to a hoisted wind generator and back at will. In the water they report 125Ah/day and 50-100Ah/day in the air.


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## mitiempo (Sep 19, 2008)

With a good battery monitor the same measuring can easily be done as well. And I think that is an essential item.
My 10 watt lights measure accurately - about .7 amps.


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## tdw (Oct 2, 2006)

scraph said:


> Well, I am a live aboard. I am in the Navy and they move me around quite often. Taking the boat from place to place for living vice another bare-walled apartment for six months at a time provides me some semblance of 'home'. I don't have the luxury of cruising around the world on my sailboat ... I do that on my submarine ... so I would prefer not to be ascribed a negative moniker because I still work for a living. But I digress...
> 
> As far as power generation ... I'd recommend taking a look at Aquair 100 (http://www.wire-wiz.com/catalog/c21_p1.html). It is a tow water generator that can be easily converted to a hoisted wind generator and back at will. In the water they report 125Ah/day and 50-100Ah/day in the air.


Hey the negative moniker is not one attributed by me and if you are moving around then at least the boat is mobile. It seems to me that the negative moniker is attached to those whose boats simply never move. Personally I don't have a problem even with that quite frankly.

Problem I see with the Aquair for Chris would be that towing the thing would probably slow him down more than the windage from a full on wind gen.


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## scraph (Oct 19, 2009)

*shrug* A good battery monitor is essentially an ammeter ... same instrument. The point remains ... measure reality and not fuse ratings/spec sheets to get realistic numbers. I certainly won't design my electrical system around assuming the largest loads are always operating at rated power (ie the radio always blasting rap music and the laptop rendering 3D graphics) ... solar panels are much too large/low output/inefficient/expensive to do that.

Your 10W bulb and my 10W bulb must have different ideas


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## scraph (Oct 19, 2009)

tdw said:


> Problem I see with the Aquair for Chris would be that towing the thing would probably slow him down more than the windage from a full on wind gen.


That's possible but ... it is cruising, not racing and with the power output of that device ... it should be all you need while underway. Leave the solar panels, wind generator, and associated mounting hardware down below because ... you can't really argue with a consistent 125Ah single source ... at least I can't. Heck, hull speed is hull speed. Just put out a little more sail.


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## chrisncate (Jan 29, 2010)

...


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## tdw (Oct 2, 2006)

scraph said:


> That's possible but ... it is cruising, not racing and with the power output of that device ... it should be all you need while underway. Leave the solar panels, wind generator, and associated mounting hardware down below because ... you can't really argue with a consistent 125Ah single source ... at least I can't. Heck, hull speed is hull speed. Just put out a little more sail.


No, you cannot argue with a consistent 125ah source.

Unfortunately Chris and Cate will be out cruising and as is generally acknowledged most cruisers spend much more time at anchor than at sea.

At anchor the Aquair is useless underwater and I really do wonder how quiet it is when hoisted into the rigging. Reality is that noise or lack thereof is the single most pressing issue with wind generators.

According to the Australian distributor the thing produces 6amps at 12v under tow (72w) and 5 amps (60w) under wind where the wind is above 24knots. So much for a nice quiet sheltered anchorage.

To be frank I think the thing has potential but I'd still rather a dedicated wind gen plus solar. (and an engine but don't tell Chris .. )


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## LandLocked66c (Dec 5, 2009)

scraph said:


> *shrug* A good battery monitor is essentially an ammeter ... same instrument. The point remains ... measure reality and not fuse ratings/spec sheets to get realistic numbers. I certainly won't design my electrical system around assuming the largest loads are always operating at rated power (ie the radio always blasting rap music and the laptop rendering 3D graphics) ... solar panels are much too large/low output/inefficient/expensive to do that.
> 
> Your 10W bulb and my 10W bulb must have different ideas


Well done sir,

I love some logic interjected in these threads, just makes me smile.


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## chrisncate (Jan 29, 2010)

...


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## mitiempo (Sep 19, 2008)

scraph

If you believe a good battery monitor, like the Victron or the Xantrex Links are just ammeters it shows a lack of understanding on your part.

I do not know of an ammeter that can tell the percentage of charge in your battery bank, nor the time you have left at present usage until a threshold of charge status, say 50%, is reached. And yes, a good battery monitor is also an ammeter.

An ammeter by itself tells current usage. Period.

I agree with tdw. If you aren't sailing anywhere for a fair length of time, and most cruisers even sailing offshore spend about 80% or more of their time in port, a towed gen isn't a big help. And the noise from even a low output wind gen like the Aquair 100 can be obnoxious. 
Solar has no moving parts to either create unwanted noise or maintenance. Once it is purchased and installed you're done. Depending on panel size and daily usage it could cover most of your daily power needs if not all. A wind gen should be the secondary option both for noise and maintenance issues. Neither solar or wind gens produce enough windage to be a big negative when sailing unless you are racing.


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## LandLocked66c (Dec 5, 2009)

mitiempo said:


> scraph
> 
> If you believe a good battery monitor, like the Victron or the Xantrex Links are just ammeters it shows a lack of understanding on your part.
> 
> ...


I think that was his point, measure actual usage. Not what's on spec sheets. That will get you closer to real life, then add some fudge factor to cover your bases. At least, that's what I draw from it.


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## mitiempo (Sep 19, 2008)

Landlocked

I was referring to the quote below. 

I agree the amperage stated in the spec sheet is not always accurate. Often it shows max amperage. Some items like the vhf will have a listed receive and a separate transmit amperage listed. But if you are creating an energy budget and either don't have all the equipment or it is not all installed yet you have to start somewhere. Lights should be fairly accurate, and as I posted mine are as I have checked them in use. Lights will not be the major usage though, especially as you are going to leds. The computers will be the larger issue, as refrigeration would also be if it was installed. If you use an inverter to power or charge the laptops it will add inefficiency to the equation, probably 10% or more.


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## LandLocked66c (Dec 5, 2009)

mitiempo said:


> Landlocked
> 
> I was referring to the quote below.
> 
> I agree the amperage stated in the spec sheet is not always accurate. Often it shows max amperage. Some items like the vhf will have a listed receive and a separate transmit amperage listed. But if you are creating an energy budget and either don't have all the equipment or it is not all installed yet you have to start somewhere. Lights should be fairly accurate, and as I posted mine are as I have checked them in use. Lights will not be the major usage though, especially as you are going to leds. The computers will be the larger issue, as refrigeration would also be if it was installed. If you use an inverter to power or charge the laptops it will add inefficiency to the equation, probably 10% or more.


I know what you were getting at. Understood, no worries. You are a wealth of knowledge, no doubt!

It's nice when a post out of nowhere comes in to breath some fresh life into a thread of regurgitated "book know how"....


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## chrisncate (Jan 29, 2010)

...


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## LakeSuperiorGeezer (Oct 8, 2010)

Modern inverters that take 12 volts DC and turn it into 120 volts AC are very efficient, like in the high 90% range. Even a large one at idle takes little. What I am thinking is you should measure the DC amps going into a small size inverter while it is supplying power to the computers and see what the actual current draw is.


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## LakeSuperiorGeezer (Oct 8, 2010)

scraph said:


> you can't really argue with a consistent 125Ah single source ... at least I can't. Heck, hull speed is hull speed. Just put out a little more sail.


Well 125 amp-hours at 14 volts needed for charging a battery would equal 1750 watts for an hour and require 2.3 horsepower to generate. At that rate, Chris should put a propeller and shaft in the boat like the one he just took out and drive a large alternator. I suppose all the propeller formulas would work in reverse, but its a lot of figuring for something I doubt Chris wants to do.


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## scraph (Oct 19, 2009)

mitiempo said:


> scraph
> 
> If you believe a good battery monitor, like the Victron or the Xantrex Links are just ammeters it shows a lack of understanding on your part.
> 
> I do not know of an ammeter that can tell the percentage of charge in your battery bank, nor the time you have left at present usage until a threshold of charge status, say 50%, is reached. And yes, a good battery monitor is also an ammeter.


My statement was that a battery monitor is essentially an ammeter. I still agree with myself. An integrating ammeter with a few clever ways to display that information but the real world->electronics conversion layer, if you will (which I'm suspecting you won't), is still an ammeter at heart. Without the ammeter taking data from the real world then your fancy battery monitor is just a retarded box wishing it had data to process.

So, they sample current every so often, multiply that value by the sample resolution, and add it to a running total. The fact that they subtract the running total from a total capacity and divide it by the instantaneous current (to determine time remaining) is not nearly a fancy enough trick to make it anything more than a fancy ammeter. Neither is subtracting the running total from a total capacity and dividing that by the total capacity again (to display a percent remaining).

Maybe they measure voltage instead and pretend like they know everything about the battery based on voltage, temperature, and a 3-dimensional look-up table relating voltage/temperature to state of charge ... but they are just guessing based on experimentally determined values.

Maybe it does both ... processes data from an ammeter (via the first method) and correlates that data with a calculated state of charge based on voltage and temperature (via the second method) ... so now it is guessing twice but making sure both guesses agree.

But, oh gosh, it will display that data in bar graph or numerical form! How does it do that?!

A battery monitor is just a trumped up ammeter (or some, granted, are trumped up volt meters) ... well, shunt type ammeters are volt meters at heart ... but I digress ... a pig in lipstick is still a pig.


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## scraph (Oct 19, 2009)

LakeSuperiorGeezer said:


> Well 125 amp-hours at 14 volts needed for charging a battery would equal 1750 watts for an hour and require 2.3 horsepower to generate. At that rate, Chris should put a propeller and shaft in the boat like the one he just took out and drive a large alternator. I suppose all the propeller formulas would work in reverse, but its a lot of figuring for something I doubt Chris wants to do.


Your point is that energy doesn't come from nowhere, I suppose? A towed generator ... is a propeller and shaft driving a large alternator. A wind generator generating [email protected] would also equal 1750W and 2.3hp. At that rate, he should put a propeller and shaft above the boat and drive a large alternator. Why, sir, do you think a wind generator provides more 'free energy' than a towed generator?

This discussion is simply splitting hairs anyways ... a wind generator or towed generator won't produce substantially different amounts of drag to produce the same amount of electricity, period. However, a towed generator will be able to produce that electricity at significantly lower operating speeds (due to the density difference between water and air)... I quit though ... too much of this discussion sounds like superstition and old habit.

Just for the record ... I don't mind the whirring of a wind generator, I could care less if a towed generator takes 0.25kts off my cruising speed, and I don't believe that solar technology has yet developed enough to save the world. Solar technology is obnoxiously overpriced and underdeveloped and I'll be damned if I'm going to put those ridiculous rectangular wings on my boat. If the 'inconvenience' of a whirring wind generator is enough to have you pay multiple thousands of dollars for 260W worth of solar panels ... then you probably are from California too and we'd be better to just agree to disagree.


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## Noelex (Jan 23, 2008)

scraph said:


> Well, I am a live aboard. I am in the Navy and they move me around quite often. Taking the boat from place to place for living vice another bare-walled apartment for six months at a time provides me some semblance of 'home'. I don't have the luxury of cruising around the world on my sailboat ... I do that on my submarine ... so I would prefer not to be ascribed a negative moniker because I still work for a living. But I digress...
> 
> To comment on measuring power requirements of equipment based on reading labels ... I don't recommend it. I have a lamp with a 10W bulb installed. I might be lead to believe that it will draw 10W / 14.1V = 0.7A. I measured it directly as 0.425A (which math calls 6W). I measured the power requirements of my stereo directly, at 50% volume, as 0.250A.
> 
> ...


Some of those figures look wrong. The stereo figure is lower than I have ever seen from a car stereo.
I know laptops have got more efficient, but only 1A to run a 17 inch laptop through an inverter. If these figures are @ 12v I think something is wrong with your multimeter or method of measurement (is it possible there was a charging source connected when you made the measurements ?)


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## LakeSuperiorGeezer (Oct 8, 2010)

noelex77 said:


> Some of those figures look wrong. The stereo figure is lower than I have ever seen from a car stereo.
> I know laptops have got more efficient, but only 1A to run a 17 inch laptop through an inverter. If these figures are @ 12v I think something is wrong with your multimeter or method of measurement (is it possible there was a charging source connected when you made the measurements?)


The charging source would have to be on the appliance side of the circuit to throw the measurement off (have a built in battery like a laptop). These multimeters with a high ammeter range are likely to have a 1% error or less. I suppose we could ask scraph what kind of meter he used and accuracy. About the stereo, it just depends on the unit; some use less than others and some speakers are low efficiency because it makes the bass a little better. Also like the stereo, it depends on the model of laptop and whether the internal battery is charged up. Chris will have to make his own measurements with his particular boat setup. In the planning stage, it is all books and assumptions since the hardware does not exist. You make your best guess, usually with conservative assumptions.

You should see the assumptions on propeller sizing with Crouch's Propeller Method. It is usually good enough for sailboats where the last bit of efficiency is not important. You come close, but the final result could be off. You could then make real world adjustments with a little different pitch. The Bp-δ method is much closer to real world in results, but of course is more complicated. I guess I am carrying on about propellers because I saw one on that well know auction site and determined it was a good match for someone until I ran the cavitation equations. Not even close.


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## LakeSuperiorGeezer (Oct 8, 2010)

*Battery Monitor/Integrading Ammeter*



scraph said:


> My statement was that a battery monitor is essentially an ammeter. I still agree with myself. An integrating ammeter with a few clever ways to display that information but the real world->electronics conversion layer, if you will (which I'm suspecting you won't), is still an ammeter at heart. Without the ammeter taking data from the real world then your fancy battery monitor is just a retarded box wishing it had data to process.
> 
> So, they sample current every so often, multiply that value by the sample resolution, and add it to a running total. The fact that they subtract the running total from a total capacity and divide it by the instantaneous current (to determine time remaining) is not nearly a fancy enough trick to make it anything more than a fancy ammeter. Neither is subtracting the running total from a total capacity and dividing that by the total capacity again (to display a percent remaining).
> 
> ...


I have wondered how they zero out an integrating ammeter/battery monitor. That is how does the device (or the boat owner) know how much amp-hours are available, as this will vary by original state of discharge of the battery if the device is reset to start integration again at some point in time. Also the amount of amp-hours is going to vary by temperature (cars in winter do not have as much amp-hours for cranking), age of battery (an old battery has a higher internal discharge rate), cells going bad from age (some of the active plate material could have sloughed off), cell equalization issues, and last but not least, entropy which will vary by construction and alloy composition in the plates. As long as you have one of those hydrometers with a built in thermometer, none of the above is a problem. For a quick check, I will measure only one cell. Besides, when you use a hydrometer, you can add water afterwards if the water level is a little low (not before you take the reading). If the water level ever gets below the plates, go buy a new battery as the old one will not hold a charge.


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## LakeSuperiorGeezer (Oct 8, 2010)

For power from a windmill, check here for your local climate: National Diurnal Climatology and make calculations from there with a current output from your windmill of choice at various wind speeds. The windmills I am familiar with for boats have a maximum output of about 25 amps. Windmills are mechanical with wind forces to deal with and rotating parts. Seems to me this would be more prone to failure than solar panels. Also in a knockdown, I am thinking the windmill would be more likely to be swept away. The most secure power source would be a water driven generator inside the boat hooked to the propeller shaft with propeller. A generator could even be wired so it would be an electric motor and drive the boat, but consider the amount of power. If you had two 100 amp-hour 12 volt batteries and took 60 amps (30 amps each battery), you would get a horsepower for about an hour and a half and discharge the batteries half way down. This is making the assumption there are no heat loss in the generator... not sure how efficient these DC motors are and whether 12 volts is enough voltage to drive a horsepower. There are specifications for trolling electric motors on the internet


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## LakeSuperiorGeezer (Oct 8, 2010)

Here is some basic information on electrical setup for a sailboat Grounding


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## Noelex (Jan 23, 2008)

LakeSuperiorGeezer said:


> The charging source would have to be on the appliance side of the circuit to throw the measurement off (have a built in battery like a laptop)..


Yes I agree I was thinking of something like a flexible solar panel plugged into a cig lighter socket.



LakeSuperiorGeezer said:


> These multimeters with a high ammeter range are likely to have a 1% error or less..


They should have, but with a flat battery in the multimeter,for example, the results can be very erratic.
I think some of the figures are out by a factor of 2 or 3X so its certainly not normal meter accuracy



LakeSuperiorGeezer said:


> , it depends on the model of laptop and whether the internal battery is charged up.


The best case (and also the correct one to measure) is the battery fully charged. I am finding it very hard to believe 1A to run a 17 inch laptop through an inverter.
My wife's netbook with 10.1 inch screen and an Atom processor running from 12v uses more than that.


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## mitiempo (Sep 19, 2008)

Here's a good link showing actual inverter inefficiency in a measured comparison. 
Inverter Inefficiency Photo Gallery by Compass Marine at pbase.com


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## Maine Sail (Jan 6, 2003)

scraph said:


> I have a lamp with a 10W bulb installed. I might be lead to believe that it will draw 10W / 14.1V = 0.7A. I measured it directly as 0.425A (which math calls 6W). I measured the power requirements of my stereo directly, at 50% volume, as 0.250A.


Sounds like you may have a mislabeled bulb or it's actually a 5 watt bulb not a 10W.

I was just in the barn and slapped a few bulbs in the test bench and measured about 12 bulbs out of about 45 I have in a bin. Each bulb was within about .02-.07 of it's rating as confirmed by a few different meters.

Bulbs are one of those items that are usually fairly accurate to their face value ratings..

15W Bulb rated at 1.25A:









20W Bulb rated at 1.67A:


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## mitiempo (Sep 19, 2008)

Here is an inexpensive dc cord for a Mac.
Amazon.com: Car Charger Dc Laptop Adapter Power Cord for Apple Mac: Electronics


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## catamount (Sep 8, 2002)

LakeSuperiorGeezer said:


> I have wondered how they zero out an integrating ammeter/battery monitor. That is how does the device (or the boat owner) know how much amp-hours are available, as this will vary by original state of discharge of the battery if the device is reset to start integration again at some point in time....


You "zero" out your battery monitor by _fully_ charging your battery. The nominal total capacity of your battery is one of the parameters you program into the thing, and then it monitors your charge current and when that charge current reaches some small fraction of the battery capacity, as it will when the battery is fully charged, the software in the monitor says OK, you're at 100%. Then it integrates amps over hours going out, incorporates a peukart factor, and reports state of charge.

I think good battery monitors can make adjustments to the peukart factor they use by keeping track of their "error" between the amp-hours that have gone out in use versus the amp-hours going in that are required to get back to that fully charged state (i.e. charge current drops below some threshold). In other words, their accuracy in reporting state of charge will improve the more often you fully charge your batteries.


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## Maine Sail (Jan 6, 2003)

Here's some actual data with pictures on a 15" Macbook Pro running nothing more than Mozilla Firefox with Wi-Fi on and running through a 175W inverter. Computers go up and down wildly depending upon what and how it is processing and what state the battery was in.

The battery in this case was at about 38% SOC.

One minute it is drawing 5.4A 









The next it is drawing 6.5A..









Even asleep and only charging it is pulling a solid 4.4A just charging the battery from 40%:









A battery monitor as mentioned earlier can easily keep track of your banks SOC. Even the smartest human sitting next to an ammeter with a pencil in hand could not possibly do that math over 24 hours and be accurate. Well okay maybe Stephen Hawking has the ability and focus to do that but what cruising sailor is going to. Tonight I may kill my Macbook battery to zero, re-set the battery monitor and charge it over night. This will give us a very accurate idea of what it takes to fully charge a Mac from dead in terms of Ah's.

I have installed battery meters for EE's who swore up and down that their "energy budget" and their "spread sheet" was as accurate as any monitor. So far not one of these customers has admitted to even being within 10% of their calculations.

Without an engine knowing your batteries state of charge is fairly important to getting the most cycle life out of your banks and a simple ammeter won't tell you that or calculate for peukert effect or charge efficiency to arrive at a consistently fairly accurate number..


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## catamount (Sep 8, 2002)

Scarph did qualify his statement by referring to an _integrating_ ammeter...


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## LakeSuperiorGeezer (Oct 8, 2010)

*Thanks, Now I Know*



catamount said:


> You "zero" out your battery monitor by _fully_ charging your battery. The nominal total capacity of your battery is one of the parameters you program into the thing, and then it monitors your charge current and when that charge current reaches some small fraction of the battery capacity, as it will when the battery is fully charged, the software in the monitor says OK, you're at 100%. Then it integrates amps over hours going out, incorporates a peukart factor, and reports state of charge.
> 
> I think good battery monitors can make adjustments to the peukart factor they use by keeping track of their "error" between the amp-hours that have gone out in use versus the amp-hours going in that are required to get back to that fully charged state (i.e. charge current drops below some threshold). In other words, their accuracy in reporting state of charge will improve the more often you fully charge your batteries.


Then there really is something to a battery monitor. I still like the hydrometer for checking on individual cells for failure, and even for checking on the state of charge. If the hydrometer says 50% discharge, then I double the amp-hours used as stated on the battery monitor and then and say that is the amp-hours available in the battery for setting the maximum amp-hours in the battery monitor. With a little checking on the battery monitor now and then, I could really get used to the convenience of the device

Oops, really, I just now looked up the definition for the Peukert factor and the article I pulled up says "Yet this is what amp hours counters attempt to do. Which is another reason why they do not work." SmartGauge Electronics - Peukert and charging. What's a person to think now.


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## tdw (Oct 2, 2006)

I wonder how North Sails are going with the development of that Solar Cell impregnated sail cloth they were working on last year. 

By the way, I emailed Aquair with some questions re their A100 unit and they tell me that the SeriesA01 is ready for release. The big news there is that instead of towing the thing they now use a through hull transducer connected to a permanently installed unit on board. The transducer can double as your log transducer so there is no need for new through hulls as such.


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## Faster (Sep 13, 2005)

Maine Sail said:


> Here's some actual data ......


Thanks, MS... that's pretty much in line with my own observations running a laptop on board last summer - using the same monitor, btw... To the OP, running a couple of macbooks for work is obviously going to be a significant load.

Our fridge uses about the same (as one PC) when it's running, but hopefully it's at a 50% duty cycle or less.


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## chrisncate (Jan 29, 2010)

...


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## mitiempo (Sep 19, 2008)

LakeSuperior

The Peukert factor is the effect of different discharge rates on battery capacity. A battery monitor manual (at least for the Xantrex Links) list Peukert factors for popular battery types as well as a method of determining the factor for different batteries. 

SmartGauge has a battery monitor unlike any other that determines status from voltage alone as far as I know. It would be to their benefit to discredit all the companies (Xantrex, Victron and probably half a dozen others) making conventional proven monitors.

While a hydrometer will tell capacity nothing can beat the convenience of an accurate reading at the push of a button. The monitor also will show a history of average discharge and deepest discharge (in amp hours) of the battery bank.
When you are trying to be self sufficient and are dependent on a battery bank of a given size, whose life is greatly shortened by discharges past 50%, the more information you have the better - and a hydrometer just doesn't cut it. The first upgrade to a boat's electrical system should be a good monitor as without it you don't know where you stand on usage and % of discharge before charging.


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## catamount (Sep 8, 2002)

LakeSuperiorGeezer said:


> Oops, really, I just now looked up the definition for the Peukert factor and the article I pulled up says "Yet this is what amp hours counters attempt to do. Which is another reason why they do not work." SmartGauge Electronics - Peukert and charging. What's a person to think now.


Yeah, I gather there is some controversy with Peukart's theories. I don't really worry too much about the details, or really care. The key thing is that batteries are not 100% efficient, you will always have to put more amp-hours in than you can get out. If you have a good smart monitor that continually re-calibrates the factor it uses every time you fully charge your batteries, the specific details of the underlying physics don't really matter, and the results will be "good enough."


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## Maine Sail (Jan 6, 2003)

chrisncate said:


> On a solar panel note, I did score my 130 watt Sharp at a pretty good deal - I got West Marine to price match Eco Direct, I got it for $435.00, it was marked at $699.00 in the store.


That's a steal and now you have money left over for this..

*Victron BMV-600 $158.10*


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## catamount (Sep 8, 2002)

That Victron looks great. There's a really interesting related link there, too:

Victron "Energy Unlimited" Book (PDF)


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## Maine Sail (Jan 6, 2003)

When you get letters from customers like this...

"_*RC,

Well I must say I am fessing up and eating my words. It has been four years since you talked Jean & I into the Xintek XBM and you were right, it is now officially cost us nothing.

Jean is in still doubt that our batteries are still operable after our normal schedule of replacing them every 18 months for many years. As you know I was positive my energy consumption chart was a good one but you were right that I was not even close. I was shocked to learn how long it takes to put the used power back into our supply and I can see how badly our consumption & charging chart had been from the git-go.

We are going on our fifth season with these batteries and if we make it through this year the Xintek has actually paid us back and we are making money.

Jean said you'd get a chuckle out of this based on my hesitation to spend this money. I have to admit now that it is one of the best items we've bought for Saphire. Jean has become the Admiral of the Xintek. She lets me know when to run the engine, and I do as I am told.

Thanks,

Bill D.*_"

Even if it is not "spot on" 100% accurate, nothing is when it comes to batteries as far as I am concerned, it can save money over the long haul..


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## chrisncate (Jan 29, 2010)

...


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## scraph (Oct 19, 2009)

Of course the laptop is pulling considerably more current while charging the battery! It is replacing all the power required to run the laptop for 6+ hours within an hour. If you never run the laptop off of the charger then it will never reach 6.5 A. If you want to get a meaningful value then you need to measure the current draw with either the battery charged or removed. You can still estimate power requirements based on that current value and time you use the laptop (plugged in or not) because all the power you don't take from the house battery while unplugged will just be replaced in a shorter time later.

In short, measuring a peak of 6.5 A while charging doesn't tell you anything about the power requirements of the laptop. Does no one understand this?! :-/


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## chrisncate (Jan 29, 2010)

...


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## Noelex (Jan 23, 2008)

To operate the laptop using the least power the best way is to measure the consumption and do the sums for average consumption per hour of use, but as a general rule. You will use the least energy if:

Using a 12v power supply you keep the power supply plugged in and the battery fully charged or removed.

If using an inverter run the laptop from its internal battery until low then plug in and charge the laptop while using it.

Computer setting, particularly screen brightness make a big difference.
Running the laptops battery low will shorten its life


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## scraph (Oct 19, 2009)

chrisncate said:


> So basically, charge with the laptop closed and powered off, and use the laptop _without_ plugging in, for optimal charging and power "delegation"?


No, sir. You don't need to over-think and I really wish others would stop confusing the topic by under-thinking it.

It doesn't matter at all whether you use the laptop plugged in or not. The amount of power that you use is determined only by what you're doing with the laptop and for how long you do it.

Charge it now, charge it later, charge it always, or charge it sometimes ... it makes no difference to the total power that you use.

Think of it like filling your water tank ... 
You could let the tank run dry as you use the water and then you'll have to refill all the water all at once (this is like using the laptop unplugged and then charging the battery later).

Or

You could connect your boat to city water and never have any water that you use come from the tank. Water comes into the boat only as you use it. (this is like keeping the laptop plugged into the charger all the time and never having to charge the battery)

Whether you have a large rate of water flowing through the hose sometimes (to refill the tank) or you have a low rate of water flowing through the house continually (only as you use the water) ... you're still using the same amount of water.

Just because it draws 6.5 amps sometimes while charging doesn't mean that is how much power the laptop requires to run. If you don't get that then I don't know what to tell you anymore!


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## scraph (Oct 19, 2009)

noelex77 said:


> Using a 12v power supply you keep the power supply plugged in and the battery fully charged or removed.
> 
> If using an inverter run the laptop from its internal battery until low then plug in and charge the laptop while using it.


Well, you're getting into questions of power supply efficiencies. I'll concede that to you. Good data, sir.


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## scraph (Oct 19, 2009)

Maine Sail said:


> Even asleep and only charging it is pulling a solid 4.4A just charging the battery from 40%:


Exactly! ... then why isn't that getting across to you the fact that the large majority of current draw that you're seeing is to charge the battery and not to actually operate the notebook! You even said it ... only charging it is pulling a solid 4.4A! Obviously, charging is the large current draw ... and then you immediately say 'just charging the battery from 40%' ... just? just? Computer asleep and _just_ charging is whats drawing the majority of the current. *sigh*

You measured current with the computer awake at 5.4 and 6.5 amps ... both with the battery at around 40%. You then put the computer to sleep and measure current at 4.4 amps.

What does that mean ... its means it requires between 1 and 2 amps to actually operate the laptop ... and it (currently) requires 4.4 amps to charge it. The _only_ reason that you are having to charge the battery _now_ is because you weren't running it on the charger _earlier_. Running the laptop off the battery wasn't free energy. You're having to make up for that energy you used now to recharge it.


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## Noelex (Jan 23, 2008)

Scraph I think you are correct to focus on the average power consumption of the laptop which is what is important to most users, but this conclusion is not correct



scraph said:


> Exactly!
> 
> You measured current with the computer awake at 5.4 and 6.5 amps ... both with the battery at around 40%. You then put the computer to sleep and measure current at 4.4 amps.
> 
> What does that mean ... its means it requires between 1 and 2 amps to actually operate the.


The laptop is limited by its power supply.when charging a flattish battery with the computer running the power supply typically cannot produce enough power to do both fully. So the battery charging rate is reduced.
Esstimating the consumption by measuring the power consumption while the computer is running and charging and then subtracting the power consumption when its asleap and charging wont give the correct value for the power to run the computer.

The Macbook will certainly use more than 1A when running with no charging. My guess would be something about 2.5A from a typical inverter and 2A from a 12v power supply.


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## mitiempo (Sep 19, 2008)

If the laptop will always be plugged into a 12 volt supply the battery has nothing to do with it and the charging power usage can be ignored.

If you will be using the battery on occasion, carry on.


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## scraph (Oct 19, 2009)

noelex77 said:


> The laptop is limited by its power supply.when charging a flattish battery with the computer running the power supply typically cannot produce enough power to do both fully. So the battery charging rate is reduced.
> Esstimating the consumption by measuring the power consumption while the computer is running and charging and then subtracting the power consumption when its asleap and charging wont give the correct value for the power to run the computer.
> 
> The Macbook will certainly use more than 1A when running with no charging. My guess would be something about 2.5A from a typical inverter and 2A from a 12v power supply.


No, it won't provide a good value for the power required only to run the laptop... and that would be a ridiculous way to determine that value especially since it is possible (and much easier) to measure it directly. I'm just attempting in every way that I can to explain something that I'm astonished is so misunderstood ... I even turned to analogies to explain!

Guessing is not necessary. You simply just need to measure the power draw with the computer on and the battery fully charged. The fact that current draw is momentarily high while charging is inconsequential and once again, the only reason the battery is charging _now_ is because it was running off of its own battery _earlier_. The power not taken from the house bank earlier (because the laptop was running removed from the charger) is simply being replaced by the charger now.

My 17" laptop does draw a minimum of 1A (and when the computer is idle but on, 1A is the majority) and a peak of around 2.5A (momentarily, only when actively processing). Typing on this forum doesn't qualify as active processing ... so even now, I am using only around 1A.

Once again, guessing is not necessary. Just measure the parameter the correct way as opposed to an incorrect way.


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## scraph (Oct 19, 2009)

mitiempo said:


> If you will be using the battery on occasion, carry on.


If you can determine a good average value of current draw while the laptop is running then you can still use that average value to estimate power requirements, whether or not you run the laptop directly off the battery (and charge later) or off the charger.

It doesn't matter whether the charger draws 6.5A for 1 hour (to charge the battery after using it for 6.5 hours) or 1A for 6.5 hour (to simply run the laptop for 6.5 hours ... both cases require 6.5Ah from the house bank. The value that you can estimate more accurately is how long _you_ will use the laptop in a day and the average current drawn when using that laptop ... not how long the charger will take to charge a dead battery or how much current it will decide to use throughout that charge.

What is the use of measuring the current while charging (which varies throughout the charge...) and then multiplying that by how long it takes to charge (exactly how long does it take to charge, eh?) and then multiplying that by how many times you need to charge in a day ... for A-hr requirements?

I promise, if you determine a good average current demand with the laptop running (and battery fully charged already/battery removed) and multiply that by the amount of time you'll spend using the laptop in a day ... you will get a meaningful estimate of A-hr requirements for that laptop. Whether you charge it now or later doesn't matter ... it really does all come out in the wash.

Measuring charging current at some point in time during a charge and using that to determine the power required to run the laptop is meaningless and only really useful to post on this thread and confuse the issue with misinformation.

I'm not authorized to be aggressive in posting anymore ... so we're back to a level playing ground where everyone with a keyboard appears just as correct as the next ... oh, the Internet.


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## AdamLein (Nov 6, 2007)

scraph said:


> I promise, if you determine a good average current demand with the laptop running (and battery fully charged already/battery removed) and multiply that by the amount of time you'll spend using the laptop in a day ... you will get a meaningful estimate of A-hr requirements for that laptop. Whether you charge it now or later doesn't matter ... it really does all come out in the wash.


Er, not quite.

I see what you're saying. You're saying, who cares how that energy gets spent? Either the laptop borrows it from the battery, which then gets topped up by the boat, or the laptop gets it directly from the boat. So just measure how much the laptop uses.

Unfortunately, there's a fee for topping up the laptop battery from the house battery. If your laptop consumes 10 Ah one day from its own battery, and then you recharged the laptop battery from the boat's bank, you will need to put in more than 10 Ah (depending on battery age, temperature, charger efficiency, position of Saturn, etc.). So if you're planning to run your laptop off its own battery at all, you'll need to account for that. If you only run the laptop directly off the house bank (laptop battery unplugged), you'll end up consuming less energy overall.


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## Maine Sail (Jan 6, 2003)

scraph said:


> Once again, guessing is not necessary. Just measure the parameter the correct way as opposed to an incorrect way.


Can you please explain why your method is the "correct way". Computers get used, plugged in and un-plugged and the batteries get drained and need to be charged perhaps even while you are using it plugged in because the battery died in the middle of something important..

The batteries need to get charged, usually at least daily. My MacBook Pro goes about 1:45 to 2 hours on a full charge. Average use is average use and includes the battery being drained and or charged so an average amp draw at 0% or 40% or 90% is all within reasonable use.. My MacBook Pro bounces all over the place current wise and it can go over 7 amps quite easily when run off an inverter. A low for this computer is about 2.2-2.4 A. And, as you said earlier:



scraph said:


> It doesn't matter at all whether you use the laptop plugged in or not. The amount of power that you use is determined only by what you're doing with the laptop and for how long you do it.
> 
> Charge it now, charge it later, charge it always, or charge it sometimes ... it makes no difference to the total power that you use.


You say that yet you keep coming back to "measuring it correctly" if it does not matter than any measurement is going to be accurate for that given moment and unless you have an Ah counter/battery monitor you'll have no real way of knowing for sure your cumulative total. I have measured it "correctly" when based on average use taking a spot check of the amp loads, just as you did. That includes average use as the "average" user would use it and checking in at a given point in time. To always measure it at 100% is not "average" as it is not accurate to always measure it at 40% or 0%. You can't attain an average with a spot check. On an engine-less boat that 100% has to be put back in somehow. The only way to properly measure it is to monitor and record the use over an average day and do so accurately. I can watch my MacBook bounce between 3.5 amps and 6 amps just sitting there typing on SailNet at many states of charge. Computers are not static devices and even measuring at 100% or without the battery you will still have fluctuations. I just saw a range of about 2.2 to 3.7 amps without the battery even installed and only Mozilla and wi-fi running. Pretty hard to track that and come up with an average. You can guess, but with no aux charging source I would want something a little more accurate, especially with two MBP's..

I am in the process of charging the MBP from 0% this takes a number of hours to do, not an "hour" with the MBP. I will note the Ah's it needed to get back to 100%, I will then will use the computer this evening wile doing some work and will then re-charge and take the cumulative Ah consumption..










*It draws 0.27A in stand by:*








*The MagSafe adapter draws another 0.1A:*








*I noted the time and state of charge at 0% using this thread:








* *Inverter on at 0% SOC with Mozilla Firefox and Wi-Fi = 7.14A:








* *The "correct way" to measure consumption is, as we've been told with the battery removed or at 100% SOC, here's the battery removed. Consumption ranged from about 3.7A to 2.2A over a four or five minute period 3.45A captured:*








*The monitor was calibrated and re-set to zero and the Trojan battery was at 100% SOC. This is the consumed energy screen (CE) showing 0.0:*








*Charging began at 1:24 PM using this thread as a reference point. Lid will be closed during charging but I will periodically open the lid just long enough to refresh the thread and read the SOC of the computer. I noted no real discernible difference in energy consumption between asleep and shut down when the battery is charging.*








*When this orange light glows green the computer is fully charged. I expect this to take a fair number of hours.*


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## scraph (Oct 19, 2009)

AdamLein said:


> Unfortunately, there's a fee for topping up the laptop battery from the house battery. If your laptop consumes 10 Ah one day from its own battery, and then you recharged the laptop battery from the boat's bank, you will need to put in more than 10 Ah (depending on battery age, temperature, charger efficiency, position of Saturn, etc.). So if you're planning to run your laptop off its own battery at all, you'll need to account for that. If you only run the laptop directly off the house bank (laptop battery unplugged), you'll end up consuming less energy overall.


There absolutely are efficiency losses associated with operation of the inverter, the laptop battery charger, and with charging a battery. I understand that as well.

The 'not quite' you are pointing out accounts for a much smaller bit of inaccuracy than the belief I've been trying with great difficultly to dispel ... that is that if you measure the current draw of the laptop charger with the laptop battery at 38% then the 6.5A you measure represents how much power the laptop requires to run and you should use that 6.5A to estimate A-hr requirements.

You and I, sir, are talking college now ... and I was just trying to get us past middle school.

The 'goes ins' equal the 'goes outs' no matter if they go in all at once or continually ... and then there are some losses to efficiency and charging losses.


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## scraph (Oct 19, 2009)

Maine Sail said:


> *The "correct way" to measure consumption is, as we've been told with the battery removed or at 100% SOC, here's the battery removed (sitting on screen) and she's still sucking down 3.45A:*
> *When this orange light glows green the computer is fully charged. I expect this to take a fair number of hours hours.*


Your computer draws about 2.2A to run itself and only to run itself... and can swing up to 4 amps during periods of higher processor load.

Your computer will run off its battery for 1.5-2 hours and takes a fair number of hours to recharge.

My computer will run off its battery for about 6 hours and takes around an hour to recharge.


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## LakeSuperiorGeezer (Oct 8, 2010)

I am thinking at this point that we need some real power consumption values from equipment that chrisncate is going to use for the Alberg. I have seen lots of variation for lighting, fans, anchor light, masthead light, depth stereo, and computer usage suggested, and any of these could be correct. There is also old radar, depth sounder, GPS, AIS VHF radio, plotter and whatever else is needed for navigation. 

For the computer and the device that will be used to connect to the internet on the boat, Chris needs to buy a battery monitor, hook it up to a 12 volt battery (marine or automotive), and take a Car Charger Dc Laptop adapter Power Cord for Apple Mac (from Amazon or some place else), plug that into the battery monitor. He could also get a converter from 12 volts to 120 volts and plug the laptop into that or even try both options. It could even be that the 120 volt converter would be more efficient than the Car Charger DC Laptop adapter cord because the DC laptop adapter also has to convert from 12 volts to about 18 volts. When you hook everything up, be very careful that positive and negative are not confused as you could burn out the electrical devices. Look at the top of the battery and you should see which post is + and -, or just know that the smaller post is – (negative, that is it is the ground). Charge the 12 volt marine or automotive battery all the way (check with hydrometer as there could be sulfation preventing a full charge). Also, charge the computer battery all the way.

The battery monitor will integrate the amount of power used over time. After you have used the computer for normal use for a week or five days, you will have consumed about 50 amp-hours if other folks here have guessed right. Look at what the battery monitor says is left. If it does not give an amp-hour consumed, you can still figure it out. Now for instance, if you have a 100 amp-hour battery value that you put into the battery monitor, take the percentage left, subtract that from 100% to get the percent of the battery used and take that and multiply times the battery amp-hour rating, in this case 100 amp-hours. It does not matter much what amp-hour battery rating you use. If you say 75 amp-hour and you have 30 percent left, according to the battery monitor, then 70% was used and consumption was 52.5 amp-hour as long as the battery is not smaller than what the computer will use. The amp-hour will be the same if the battery is larger (or we only think it is larger, whatever value was originally put into the battery monitor) so say we think we have a 125 amp-hour battery and we took 52.5 amp-hours from it, the battery monitor will say 58% is left because we used 42% (52.5/125). And 42% of 125 amp-hour is of course 52.5 amp-hour of actual use in our example. I am over analyzing this, just guess at an amp-hour rating for the battery, put it in the monitor, get a percent left, subtract that from 100%, take that percentage and multiply it by the guessed at amp-hour rating for the battery and that is the amp-hour used by the computer for the week or work week. Keep track of how many hours you actually used the computer because it might not actually be seven hours a day for each day of use so you will have to adjust up or down.

Chris, you also need to determine power consumption for the actual lighting, fans, anchor light, masthead light, depth finder, and stereo you will use. There is also old radar, depth sounder, GPS, AIS VHF radio, plotter and whatever else is needed for navigation. Make some actual selections and purchase them and hook up the above mentioned setup, or at least get some power consumption values from what contributors here on sailnet have suggested. Lets get some real values to work with, or as close as we can. Otherwise, lets just go with four solar panels if there is room above the bimini and cockpit for them and call it good enough, but I still wonder how much power the radar takes. It is good to run radar because ships see your radar signal and use that to avoid running you down if they are watching things as they should be. You can also use the AIS VHF to signal your location, and to get a location on any approaching shipping. Many smaller boats will not have this electronics like fishing boats, sail and power boats. If you have a modern radar setup, these smaller boats can also be detected electronically and give you a warning, but not so sure about how good a return signal you get fiberglass. Make sure you have a radar reflector yourself if your radar is off. You should also keep up a visual scan of course, but you really must set a timer for every 15 minutes as large ships can really sneak up on you, not to mention smaller craft even if slower.


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## AdamLein (Nov 6, 2007)

Guys isn't there a way, in software, to ask your laptop's batteries for the current state? ACPI or some such?

Linux (and OS X is sort of Linux-esque, right?) systems have a file called /proc/acpi/battery/BAT0 that will tell you the battery state. As I recall, this includes current amp draw. Could somebody write a program that will read from this file, integrate the amps over the period of a month or something, and figure out the distribution of daily loads, and end this crazy debate?

edit: you know what, just check for a /proc/acpi/battery/BAT0 file and I will write your integrator for you.


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## Maine Sail (Jan 6, 2003)

scraph said:


> I'm not authorized to be aggressive in posting anymore ... so we're back to a level playing ground where everyone with a keyboard appears just as correct as the next ... oh, the Internet.


If by aggressive you mean rude and discourteous to other posters than I thank the staff here at SN for asking you to be more polite.

The keyboard and civility have nothing at all to do with being correct. If you think calling folks names and degrading others to prove your point helps make your point rather than actual data and cohesive friendly conversations well then I feel sorry for you... Being helpful is all what we are trying to do, not be right.

The OP has two Mac Books I happen to have one too..

*So it's now 3:30 and we've charged to 52% apparently the wi-fi did not refresh when I opened the lid:*









*And burned 5 Ah's doing so through the inverter:*


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## chrisncate (Jan 29, 2010)

...


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## AdamLein (Nov 6, 2007)

chrisncate said:


> ...


What I've taken from all this is that basically the screen on MaineSail's laptop is really wide.


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## catamount (Sep 8, 2002)

LakeSuperiorGeezer said:


> It is good to run radar because ships see your radar signal and use that to avoid running you down if they are watching things as they should be. You can also use the AIS VHF to signal your location,...


I don't think ships can see your radar signal on their radar -- can they? If you want them to see you on their radar you should do what you can to enhance your radar "reflectiveness", like get one of these: Echomax Active-X Band Radar Target Enhancer Having your own radar, so _you_ can see _them_, is still good, too.

Also, I don't think the current version of combined AIS-VHF radios include an AIS transceiver, do they? They just have an AIS receiver, right? So you would not be able to signal _your_ location, although you would be able to detect other vessels that are transmitting AIS information.


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## AdamLein (Nov 6, 2007)

I think catamount is probably right about the radar thing. They'd have no way of figuring out the range since they don't know when the signal was sent. However I imagine radars can cause interference to one another.... don't know much about such systems.


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## chrisncate (Jan 29, 2010)

...


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## scraph (Oct 19, 2009)

AdamLein said:


> I think catamount is probably right about the radar thing. They'd have no way of figuring out the range since they don't know when the signal was sent. However I imagine radars can cause interference to one another.... don't know much about such systems.


On Navy vessels, we have a general classification of equipment installed providing ESM (Electronic Support Measures). This equipment provides active emissions detection and classification. We know if and when we're being painted by RADAR, we know roughly how close the source is (as in, Near, Medium, Far), and we can distinguish between different sources and types of RADAR. With ESM, you don't need a numerical value of range. You simply need to know if a RADAR transmitter is close. I can't comment on whether commercial vessels use this equipment ... I doubt it.


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## mitiempo (Sep 19, 2008)

So there you go - the Navy won't run you over, the freighter will.


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## scraph (Oct 19, 2009)

Maine Sail said:


> Being helpful is all what we are trying to do, not be right.


Well, that is ridiculous! In what sort of world can you be one without the other? Wrong information is never helpful. If you want to be helpful ... it is far more important to be right than to give wrong information in a very courteous and polite manner.

If you want to be helpful without the burden of being right then you should probably just be silent. And no, PC police, that is not a direct attack on anyone ... if it doesn't sound familiar to you ... it's probably just something your father should have taught you.


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## Maine Sail (Jan 6, 2003)

It's now 6:37 and in a little over 5 hours the MacBook Pro has charged from 0% to 95% using 9.6 Ah's to do so through a 400 watt inverter..










9.6 Ah's consumed to charge:









I don't know which MacBooks CnC have but my MBP 15" will use about 10 Ah's just to charge per day if depleted to zero. My MPB will go about 1:45 to 2 hours so if you used it less than 2 hours per day you could use just 10 Ah's per computer per day if they are similar to mine. Perhaps newer ones charge faster but in my experience the MBP takes many hours, in this case over 5 hours to charge and it is still only at 95% SOC. This is still 20+/- Ah's per day just for two computers. Using it 4 hours a day could double that figure..


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## scraph (Oct 19, 2009)

If your MBP 15" has the standard size battery then that battery is 60W-hr

Dividing that by 12V and 14.3V ... we see that it looks like anywhere between a 4.2Ahr and a 5Ahr to your DC bus.

Best case, it's looking like your inverter/charger/battery combo is 50% efficient in charging the battery. Worst case efficiency for that Cobra CPI 475 is >83% (spec at full load) so the best case efficiency for the MBP charger and battery during this charge is 60%.

You are inverting 12V -> 120V and then rectifying and regulating 120V -> 14.5-18.5V.

To the OP, if you want to take the largest load on your boat and cut the power consumption nearly in half, you absolutely want to get a DC-DC converter and throw the Power Inverter->AC Charger out the window.

HyperMac Introduces World's First DC Car Charger For All Apple MacBook Models - Sanho Corporation - pitchengine.com

They advertise a DC charger for your laptop and also claim the same 50% efficiency numbers that Maine Sail has proven here.


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## LakeSuperiorGeezer (Oct 8, 2010)

If you want to generate power from the propeller where the engine was, here is a propeller on ebay that is a 13X11 RH with a one inch shaft that could be used with a geared down electric motor. If need be it could also be used with a 2GM20F if you ever change your mind about diesel. The color is described as "It shines up like a old copper penny. More yellowish than red" so this must be silicon bronze which is hard and very corrosion resistant, unlike modern manganese bronze propellers (really a brass) that will have dezincification problems if the zinc anode does not do its job, or is not replaced periodically. If you don't want the propeller, I am sure your artist friend would like to make a statue out of it. Boat Propeller Bronze 3 blade 13R11, 1" Dia Shaft NR! - eBay (item 170621144437 end time Apr-03-11 18:24:18 PDT)


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## LakeSuperiorGeezer (Oct 8, 2010)

*Ais*



catamount said:


> Also, I don't think the current version of combined AIS-VHF radios include an AIS transceiver, do they? They just have an AIS receiver, right? So you would not be able to signal _your_ location, although you would be able to detect other vessels that are transmitting AIS information.


This is probably too much information Automatic Identification System - Wikipedia, the free encyclopedia

And if you want the transponder system: MA-500TR Class B AIS Transponder - Features - Icom America


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## catamount (Sep 8, 2002)

LakeSuperiorGeezer said:


> This is probably too much information Automatic Identification System - Wikipedia, the free encyclopedia
> 
> And if you want the transponder system: MA-500TR Class B AIS Transponder - Features - Icom America


Geezer, I know all about AIS and AIS transponders, thanks. When you wrote _"You can also use the AIS VHF to signal your location,..."_ I thought you were making reference to something like the Standard Horizon Matrix AIS GX2100 VHF radio, which combines an AIS receiver with a VHF radio -- this unit will not "signal your location..." (unless of course you are issuing a DSC call...)


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## catamount (Sep 8, 2002)

scraph said:


> On Navy vessels, we have a general classification of equipment installed providing ESM (Electronic Support Measures). ..... I can't comment on whether commercial vessels use this equipment ... I doubt it.


And such equipment is probably not installed on too many recreational vessels, either.


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## chrisncate (Jan 29, 2010)

...


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## scraph (Oct 19, 2009)

catamount said:


> And such equipment is probably not installed on too many recreational vessels, either.


The Echomax Active-X active radar reflector has the capability to produce an audible alert whenever it is painted by a radar signal. It doesn't tell you much (range, rate, type, number) but it does alert you to the presence of a radar transmission.


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## tdw (Oct 2, 2006)

scraph said:


> I'm not authorized to be aggressive in posting anymore ... so we're back to a level playing ground where everyone with a keyboard appears just as correct as the next ... oh, the Internet.


Lets be quite clear about this. You were never authorised to be agressive in your posting, at least not on SailNet. You want to play that kind of game, go to Sailing Anarchy. There they will have you grilled on toast for breakfast , your problem not mine. Simply put, don't play your infantile games here or you will be taking an extended vacation.

You are correct in one thing however, everyone is playing on a level field, a level field where every asshat is as expendable as the next.

regards


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## catamount (Sep 8, 2002)

scraph said:


> The Echomax Active-X active radar reflector has the capability to produce an audible alert whenever it is painted by a radar signal. It doesn't tell you much (range, rate, type, number) but it does alert you to the presence of a radar transmission.


Yes, I have one installed on my boat, but I appear to be on the cutting edge in that it seems very few other boats in the US have gone for something like the Sea-Me or the Active-X yet. But you were talking about the Electronic Support Measures installed on Naval warships -- are you really comparing an Active-X to the ESM on a warship?

The point is that another boat's RADAR set is not going to see the signal sent out by your boat's RADAR set, which is what Geezer seemed to be implying in the post I was responding to.

If you want to improve the chance that you might be seen on another boat's RADAR set, you need to enhance your radar "reflectiveness." Adding your own RADAR set doesn't do much for that, building a metal boat or using an Active-X or Sea-Me does.

This is not to discourage you from carrying your own RADAR set, that's a very good thing to do in it's own right.

But, back to the original discussion in this thread, most RADARs are very power hungry. CnC referred to an "old' radar that came with the boat -- does it have a CRT display rather than an LCD panel? You're going to need an engine/generator to support running such a beast.


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## chrisncate (Jan 29, 2010)

...


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## LakeSuperiorGeezer (Oct 8, 2010)

*Senior Moment*



catamount said:


> The point is that another boat's RADAR set is not going to see the signal sent out by your boat's RADAR set, which is what Geezer seemed to be implying in the post I was responding to.


I tried to find where I though I saw a device that would see another radar signal and track it, but could not find anything. I must have confused it with the ability that radar has to track the course of another vessel and plot how close the two will come to each other. Frankly I also thought that a VHS AIS radio could also have the ability to transmit location information, but that is a separate transmitter that can share an antenna with the VHS AIS radio. It seemed to me that the two had been combined into one unit, but I was mistaken. Maybe someone could develop such capability into a VHS AIS radio and make a bit of money at it. When I make statements here I try to have some source of information I can reference back to if someone challenges it, but not this time.


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## LakeSuperiorGeezer (Oct 8, 2010)

*Aperture Cutout?*



chrisncate said:


> I will be filling in the prop aperture cutout, as well as the rudder cutout. Cool idea though, other than the drag.


This could also be used as a water generator, but whether a windmill or water generator, there will be drag of course. The light from the sun, though, obviously presents no drag, but gives no energy at night which means a bigger battery bank. If carefully secured, probably above the bimini, I think solar panels are the way to go.

How do you plan on filling in the aperture in the rudder and hull?


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## scraph (Oct 19, 2009)

catamount said:


> But you were talking about the Electronic Support Measures installed on Naval warships -- are you really comparing an Active-X to the ESM on a warship?


Well, yes ... I am. I've never used an Active-X but I have used ESM plenty and simply being alerted to the presence of a radar signal is the key feature that we'd find use for! You don't really need all the other features so much when you're using more than a periscope and aren't worried so much about hiding...


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## LakeSuperiorGeezer (Oct 8, 2010)

*Radar Amps*



chrisncate said:


> My radar is a JRC model 1000 MKII (LCD display).


So, what does the plaque on the unit say about the number of amps it uses?


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## LakeSuperiorGeezer (Oct 8, 2010)

Did a search on bimini solar panels:
Bimini for Solar Panel Support - Cruisers & Sailing Forums
Solar panels: Arch vs Bimini - Cruisers & Sailing Forums
Solar Panel Installation Aboard

There's a lot more than the above 
You could also search on arch solar panels


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## chrisncate (Jan 29, 2010)

...


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## chrisncate (Jan 29, 2010)

...


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## Noelex (Jan 23, 2008)

chrisncate said:


> I realize it's limitations, however it's a nice compromise between functional and seaworthy. Couple this with a forward hatch panel (a hatch that has a small panel embedded within it):


There are difficulties mounting solar panels on boats, but the solar panel pictured is going to get some fairly severe shadowing no matter where the sun is coming from. You did say you understood the limitations, but most people underestimate the effect of this sort of shadowing. Any solar cell in deep shadow will not conduct electricity shutting down not just the cell in shadow but all the other cells connected in series to it.
Its difficult to predict the effects of this, but my guess would be the panel pictured will give out something like 1/4 of the output (on average) that you would get from a well mounted panel.
.


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## mitiempo (Sep 19, 2008)

Like this from James Baldwin's site.


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## LakeSuperiorGeezer (Oct 8, 2010)

Specific to sailboats about shade:
Genasun
Installing solar panels on a boat


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## casey1999 (Oct 18, 2010)

catamount said:


> Geezer, I know all about AIS and AIS transponders, thanks. When you wrote _"You can also use the AIS VHF to signal your location,..."_ I thought you were making reference to something like the Standard Horizon Matrix AIS GX2100 VHF radio, which combines an AIS receiver with a VHF radio -- this unit will not "signal your location..." (unless of course you are issuing a DSC call...)


I have a CARD system on my boat (was installed by PO) it basically is a radar detector that gives the direction only of where the radar signal is coming from. It does have a sensativity adjustment but the transmission signal can vary so no way to tell how far away- but better than nothing and it is very inexpensive and simple.


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## casey1999 (Oct 18, 2010)

LakeSuperiorGeezer said:


> This could also be used as a water generator, but whether a windmill or water generator, there will be drag of course. The light from the sun, though, obviously presents no drag, but gives no energy at night which means a bigger battery bank. If carefully secured, probably above the bimini, I think solar panels are the way to go.
> 
> How do you plan on filling in the aperture in the rudder and hull?


I see where Japan has some used nuclear electric power plants for sale on E-Bay. Description says as-is where-is and must be moved from present location by May 1, 2011. Maybe you could make a power barge to be towed by the Alberg.


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## casey1999 (Oct 18, 2010)

casey1999 said:


> I have a CARD system on my boat (was installed by PO) it basically is a radar detector that gives the direction only of where the radar signal is coming from. It does have a sensativity adjustment but the transmission signal can vary so no way to tell how far away- but better than nothing and it is very inexpensive and simple.


Here it is SURVIVAL SAFETY ENGINEERING


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## tdw (Oct 2, 2006)

casey1999 said:


> I have a CARD system on my boat (was installed by PO) it basically is a radar detector that gives the direction only of where the radar signal is coming from. It does have a sensativity adjustment but the transmission signal can vary so no way to tell how far away- but better than nothing and it is very inexpensive and simple.


Casey,
That sounds like an excellent piece of kit. It seems to me that unless budget is not a consideration then simply knowing something is out there and which direction it is coming from should be enough.


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## casey1999 (Oct 18, 2010)

tdw said:


> Casey,
> That sounds like an excellent piece of kit. It seems to me that unless budget is not a consideration then simply knowing something is out there and which direction it is coming from should be enough.


Yea, I see where Jesse Martin used this exact system on his single hand around the world (can be seen in Lionheart DVD). It is good if you want to sleep and set the alarm to wake you if you are iluminated by someone else's radar. Unfortunately alot of freighters do not use radar, running lights, AIS, or at times even have someone on the bridge. But then sailing is still probably safer than dring a car.


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## catamount (Sep 8, 2002)

I am aware of the CARD, although I'm not sure where or how you go about actually buying one these days (there is no "buy now" button on the linked page), and I have heard mixed reviews of them over the years. Are they still being manufactured and supported?

The Echomax Active-X and the Sea-Me Radar Target Enhancers do also act as radar detectors -- they won't tell you from which general direction the radar signal is coming like the CARD does, but they can alert you to the fact that there is a boat using radar out there, as the CARD does.


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## LakeSuperiorGeezer (Oct 8, 2010)

casey1999 said:


> I have a CARD system on my boat (was installed by PO) it basically is a radar detector that gives the direction only of where the radar signal is coming from. It does have a sensativity adjustment but the transmission signal can vary so no way to tell how far away- but better than nothing and it is very inexpensive and simple.


Here is some more info: Radar/ais detector - Yachting and Boating World Forums


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## tdw (Oct 2, 2006)

LakeSuperiorGeezer said:


> Here is some more info: Radar/ais detector - Yachting and Boating World Forums


Thanks for the lead.


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## w1651 (May 2, 2010)

Has anyone ever seen one of these? It's a great little idea. You can run it for a short time and completely charge a battery bank while underway or at a dock or on the hook. Their new only been out a few years but I think they call them a generator.

800 Rated Watts/900 Max Watts Portable Generator


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## mitiempo (Sep 19, 2008)

It will power a small AC charger but it wouldn't be efficient at charging the battery bank past 80%. The last 20% would take many hours as battery acceptance lowers.


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## AJSquaredAway (Apr 6, 2011)

mitiempo said:


> It will power a small AC charger but it wouldn't be efficient at charging the battery bank past 80%. The last 20% would take many hours as battery acceptance lowers.


That's true. That's precisely the reason for not even attempting to fully charge the battery bank during routine cycling. Take the battery bank down to around 50% and recharge until charge acceptance rate lowers markedly.

I have a Yamaha EF2000iS inverter/generator and a TrueCharge2 60A battery charger to support charging my 450Ah (540Ah including starting battery) battery bank. The inverter/generator is miraculously quiet. Most of my time is spent on shore power with ~1000 mile passages every few years. I can't, given this cruising schedule, justify 'altenative energy' sources and the generator/charge combo suits me fine.

(edit by tdw - Banned users are not permitted to re register under new user name)


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## matt195583 (Mar 21, 2011)

Well this has proven an interesting thread. I have just read it start to finish, and paid particular attention to the whole debate on laptop consumption. I still fail to see Maine Sail's Problem with Scraphs's method of measuring consumption. 

Correct me if I am wrong here.

Consumption with battery at 100% is actual laptop consumption.

Consumption with battery in discharged state is higher, ie: consumption + charging. In effect to work out the actual consumption of the said lap top being used unplugged then charged. one would record the time used (operational) while unplugged ( 2 hours for arguments sake ). Then take the time while charging and in use, for instance 6 hours. If the current draw was an average of 6 amps for 6 hours it would have used 36 amp hours. 
So 8 hours actual use for 36 amp hours. An average of 4.5 amp hours. 

If the average consumption while plugged in and fully charged was 3 amp hours that 8 hour period of use would have cost 24 amp hours.


It is late here and I couldn't remember the exact figures Maine Sail quoted for his usage but im pretty sure my hypothetical ones are close to his. 

One thing I have taken from reading this thread Is that If you were to use a laptop on a yacht you would be better off to keep the battery topped and run off a 12v charger or remove the battery completely. For the purpose of eliminating inefficiency ( loss during battery charge and inverter losses if you did not havethe 12v charger)


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## AdamLein (Nov 6, 2007)

matt195583 said:


> Consumption with battery at 100% is actual laptop consumption.
> 
> Consumption with battery in discharged state is higher, ie: consumption + charging. In effect to work out the actual consumption...


I think this relies on a couple of assumptions:

1) that the laptop battery does not significantly self-discharge.

2) that the controller is smart enough to bypass the battery while the laptop is plugged in (i.e. and not discharge the battery to power the laptop; could be that the battery is always used but continuously recharged).

3) that the number of amp hours that come out of the fully charged battery during use is equal to the number of amp hours that will have to go back in to fully recharge the battery.

I don't know about lithium ion batteries, but (1) and (3) are false for deep cycle batteries. Also (2) has always been a mystery to me.


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## rhsanborn (Jul 17, 2010)

I don't know that anyone disagreed with scraph's point, just his tone. I think a lot of people read that tone and stopped reading his post. 

It is indeed unfair to characterize the charging profile of a laptop as the continuous use profile. It's also worthwhile to know what the charging profile is and make sure the bank can handle it (ans whatever else you want to do at the same time). I would also be interested to see the draw using a 12V charger. The problem with using inverters isn't the 12V - 120V conversion. Most liveaboards and long-term cruisers would do well to buy an efficient inverter. The problem is the transformer that comes with the laptop, which is likely much less efficient, something like 70 - 80%. 

Chris, what kind of work do you two do? New laptops probably aren't in the budget, and the newer MacBooks are pretty efficient, but it might be advantageous to plan on replacing one of those 17" monsters with a 13" or an Air when it's due for replacement. But it depends on how much screen real estate you need.


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## casey1999 (Oct 18, 2010)

catamount said:


> I am aware of the CARD, although I'm not sure where or how you go about actually buying one these days (there is no "buy now" button on the linked page), and I have heard mixed reviews of them over the years. Are they still being manufactured and supported?
> 
> The Echomax Active-X and the Sea-Me Radar Target Enhancers do also act as radar detectors -- they won't tell you from which general direction the radar signal is coming like the CARD does, but they can alert you to the fact that there is a boat using radar out there, as the CARD does.


C.A.R.D.
Lynn Marine is a boating and sailing supply store on Marbleheads harbor.

Here is more information on the CARD radar detector. I am not sure if it is still available. Price a little higher than I thought.


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## matt195583 (Mar 21, 2011)

> run off a 12v charger or remove the battery completely


If the battery was able to be removed completely it would eliminate the discharge while at 100% charge and plugged in issue if indeed it was discharging.



> 3) that the number of amp hours that come out of the fully charged battery during use is equal to the number of amp hours that will have to go back in to fully recharge the battery.


I would never assume that a battery and charging circuit is 100% efficient, we are a long way off having that luxury. and it was proven not to be the case in Maine Sail's testing of his own macbook.


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## w1651 (May 2, 2010)

mitiempo said:


> It will power a small AC charger but it wouldn't be efficient at charging the battery bank past 80%. The last 20% would take many hours as battery acceptance lowers.


True but for the immediate need it's perfect for what he is asking for. This little generator uses gas for fuel can basically run the boat and charge the batteries while under way. Just place it on the deck strap it down and you have instant power and charging for an hour a tank of gas. Then use a solar panel for the rest.
Look we all know that nothing is going to satisfy everyone or every need out there. In fact I think what he is looking for is a little out of grasp anyway. But for a in a pinch solution this is the best one.
Personally I would add solar panels as a bimini and a wind generator with a battery switch capable of turning the entire boat off for charging underway alone. But that's just me.
Learning to deal with the top heavy aspect of all the equipment is part of the overall cruising experience at this point in time. As soon as we all get self contained nuclear reactors installed in our hanging lockers were just gonna have to grin and bear the needs of our wives and girlfriends against the power needs of all the equipment they just can't live without.:laugher


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## mitiempo (Sep 19, 2008)

As long as his AC charger is small enough to run with the generator that was linked to. Many marine chargers give less than full output from a generator unless it's output is about double the charger's AC usage. A typical charger such as the Xantrex Truecharge2, 40 amp version has a max draw of 9 amps, a bit more than the gen linked to puts out. He would be much better off with the Honda EU2000.


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## w1651 (May 2, 2010)

But you get the point intended mitiempo?


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## mitiempo (Sep 19, 2008)

Yes. it works in a manner. But removing an inboard diesel for a tin can gen rattling on deck for hours doesn't seem like a good trade off somehow.

Best, least annoying solution is an arch or solar sticks at the stern with enough wattage in panels to cover most needs, miserly usage of power, and if a gen is to be part of the equation at least one gutsy enough to handle an AC charger efficiently. One quiet enough that your neighbors don't all leave and quiet enough that you lose the desire to toss it overboard.


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## LakeSuperiorGeezer (Oct 8, 2010)

Just put as many solar panels on the boat as possible and forget the generator. It looks like the lap top computers are power hogs, but we do not really know how much, and in the winter there will be less solar for the panels anyway that far north. Or at least leave plenty of room for more panels, try two 135 watt ones at first and see how it goes. Get a human powered generator for emergency use.


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## casey1999 (Oct 18, 2010)

I see where you plan to use the composting toilet. I looked into that toilet but just do not see how it could hold the waste from two people for a month. Especially when the toilet paper does not decompose well. What do you do at see, through the toilet paper over board and not into the toilet?


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## AdamLein (Nov 6, 2007)

By the way, found this pretty useful page at the Energy Star site:

ENERGY STAR

You can use this form to list computers based on (a small number of) your needs and sort by this "Typical Energy Consumption" value that they compute based on a formula and some research.

For example, the laptop with the lowest TEC running Windows 7 and more than 2 GB of ram is the Toshiba Satellite Pro, at 16.6 kWh/year, which is 45 Wh/day. Not bad considering the power supply on my laptop at home tells me it consumes 65 watts.

Just had a look at the MacBooks, and they're even lower, the lowest being 10.9 kWh/year.

You should probably take their numbers with a grain of salt, but it's probably good for comparison purposes.


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## chrisncate (Jan 29, 2010)

...


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## casey1999 (Oct 18, 2010)

chrisncate said:


> Where do you get your info from? A composting toilet like the Natures Head works very efficiently and does indeed compost the paper (you use one ply, just like in a normal marine head). Compost, as it "cooks" becomes smaller than the original matter that created it.
> 
> My question to you is how do you live with knowing that there are a bunch of bits of solid matter and urine mingling in your hoses that you can never really get out or get clean (hence the smell from your head)? _That's_ pretty gross imo... composting heads smell like soil and are totally separated from the boat, and totally self contained (see: clean).


Chris,
Actually I do not have an installed head. I use a pot a pot and store waste on board in a 5 gallon sealed bucket ( after mixing with lime- same way my grandparents and great grandparents did it living in a cabin in the Apalachian Mountains). It was the same port a pot used by Natasha in her around the world single handed cruise. I bought the boat from her when she returned to Hawaii. Details here Natasza Caban - Solo Around The World Check out here blog- a lot of interesting information about real life at sea.

With the composting toilet, if I take a full 360 deg roll say in the southern ocean, what happens to the material in the composter. Will it stay in the toilet? Also, do coffee filters decompose?


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