# AGM Batteries



## davidpm (Oct 22, 2007)

I recently heard a forum member mention that he thought a lot of people were going to AGM batteries for the wrong reason.

I found that was an interesting comment, what might that reason be.


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## sailingdog (Mar 19, 2006)

AGM Batteries are great if you don't like doing battery maintenance, need to stow batteries in odd positions and locations, and have a pretty high amperage charging capability. 

They are not a panacea for electrical problems. They have to be charged properly, charged completely at least once a month or so, and are quite expensive compared to wet-cell batteries. 

The way most people use their batteries, they really don't provide any real benefit, other than the lack of maintenance.


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## JohnRPollard (Mar 26, 2007)

I agree with Dan's summary, and will add that another benefit is their high acceptance rate and low self-discharge rate.

I disagree with those who say they offer little benefit for most users. I've heard some say that they are best for cruisers. I would say they are great for anyone who can afford them, but especially for non-live-aboard-cruisers.

I say that, because unlike live-aboards or long-term cruisers, most boat owners have to divide their time between home, job, family, etc and boat. Anything that eliminates yet one more maintenance task, and offers better performance to boot, is a welcome alternative and worth a premium.

The low self-discharge rate is especially advantageous to folks who only visit their boats every few weeks and don't have access to charging via shorepower -- for instance, folks who keep their boats on moorings.

We switched a decade ago, and I'll never go back to wet cells.


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## Maine Sail (Jan 6, 2003)

Wrong reason's that I have seen:

*#1* Bought a 200-800 ah bank for their high acceptance rates then fed them with a 100 amp alt and 40 amp shore charger.

*#2* Bought them for the "low maintenance" then ran the engine 35 hours a season. Even the worst wet cell on the worst charger won't boil off on 35 engine hours per year.

*#3* Bought them for low self discharge rates then left them sitting at 50% - 80% charged after each sail and killed them in three seasons.

*#4* Bought them for the claimed "longer life" then found out they were dead in 4 seasons anyway, when his previous wet cells lasted 7.

*#5* Bought them to replace wet cells that died a premature death then the AGM's proceeded to do the same because the owner refused to address his/her battery practices.

*6#* Bought them because they don't give of "gas fumes" when charging. (His previous bank had zero signs of corrosion and in four years had never even taken water. When I opened them up they were still full and load tested at nearly new. Gave that bank to a friend who got two more seasons out of them. The "new" fumeless AGM's died at year five.....)

*#7* _"The guy at West Marine said they were the best."_ He then proceeded to fry two stock alternators and finally had to buy a fully gourmet charging system for another 1.3k. Previous wet bank on dumb regulated alt lasted six years and cost $300.00 vs. $1000.00 + $1300.00 alternator regulator installation. $2300.00 vs. $300.00. I'll be surprised if he gets 6 years out of the Deka/WM AGM's (only on year two now)...

I see and work on boats left on moorings, it's Maine, and the only thing I can ascertain is that AGM's do not like to sit discharged as mooring boats often do. I have seen LOTS of expensive AGM banks die before 5 seasons. I also check date codes every time I am at my local battery distributor on the core pallets. The 6 year old AGM core is a rather rare up here while the 6 & 7 year old wets are not all that uncommon on the pallet. Most of the dead AGM date codes are between 4 & 5 years at Dave's shop.

Nearly every boater I know with AGM's has bought them for their ability to take a fast charge then fed them with a diminutive alt that took no advantage of the high acceptance (wrong reason #1). I have personally seen a 100 Ah Lifeline take 85 amps for more than just a few minutes. I have yet to see any boater truly take advantage of the actual acceptance rates on a large bank because you'd need a HUGE alt to do so and small sailboat AUX engines just can't do this.

I replaced four T105's on a Sabre 362 that had lasted 7 years with a 90 amp dumb regulated alt. Boat resided on a mooring with no solar or wind. The Lifeline bank cost over $1400.00 and was flat dead going into the spring of what was to be their fifth season. At the same time we upgraded the batts we did a full gourmet charging system with 150 amp alt, dual pulleys, MC-612 Balmar regulator, temp sensing etc. etc. on and on. He even bought a maintenance charger that was recommended by Lifeline tech support for the off season where they were stored in his 55 degree basement and cycled on and off the charger to keep them at 100% SOC. Total cumulative motor run time over the four previous seasons was just over 400. The bank had never been discharged below 60% SOC during these four seasons as monitored by Link 20. Dead, grave yard dead. Lifelines attitude, not out of the ordinary, try equalizing. He's back to 6V wet cells again, expensive experiment.. This is one I really feel terrible about because at the time I had bought the AGM static hook line and sinker and really pushed this guy towards this set up. I have wracked my brain as to what cased this but there is no answer. Everything was done by the book.

Oh and then their is my buddy who is the head systems tech at a very well respected boat yard here in Maine. He is an ABYC marine electrician, NEMA certified etc. etc. on and on and on. Probabaly one of the best marine guys I know in tems of knowledge. His own bank of AGM's in his own boat lasted three seasons (Deka's). He's gone to gel.

Don't get me wrong, there ARE benefits to them, and if you can truly take advantage of these benefits they can definitely be worth it. Most I see don't truly take advantage of the benefits. If you go AGM try and keep them fully charged as best you can. If on a mooring get solar or wind to augment. If you can afford a $1300.00 bank you should really take care of them. In my opinion and based on the "claims" these banks should have all easily gone 7+ years.

I had planned to go to AGM but I am still with wets because I have been able to live vicarously though many friends and customers AGM trials and tribulations.


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## davidpm (Oct 22, 2007)

Maine Sail said:


> I had planned to go to AGM but I am still with wets because I have been able to live vicarously though many friends and customers AGM trials and tribulations.


What a great post RC. Who would have thunk. Something new and expensive don't live up to expectations.
Maybe NiCad, Lithium or some such technology will save us some day.


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## Maine Sail (Jan 6, 2003)

davidpm said:


> What a great post RC. Who would have thunk. Something new and expensive don't live up to expectations.
> Maybe NiCad, Lithium or some such technology will save us some day.


I think if AGM's are left topped up, like if you are on a dock regularly, they can last as long as wets but I have yet to hear of many success stories where AGM's clearly out lasted good quality deep cycle wets. The original claims were many, many more cycles than wets.

I have only topped up my bank of wets ONCE in the last four seasons, took me all of three minutes. My bank cost me $240.00. The same bank in Lifelines would be about $1000.00. A $760.00 savings for 3 minutes work is a good pay to me...

I find this to be an interesting quote by Trojan Battery. When AGM's first came out the claims were BETTER cycle life than wets..



Trojan Battery said:


> *Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries.* However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries (see table below). Gel batteries are more suitable for deep cycling applications whereas *AGM batteries are more for light cycling and engine-starting applications.*


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## sailingdog (Mar 19, 2006)

This is why I'm using wet cells too.  I like my money to stay MY MONEY.


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## remetau (Jan 27, 2009)

We recently replaced our 3 year old 210 AH AGMs with wet Trojans. We discovered that living at anchor, we couldn't get the AGM batteries to 100% as often as they like. The company who made them even replaced all 3 batteries when they died for free, including shipping them to the Keys. After we had problems with the second set, we had had enough and decided to replace them with wet cells.

I think AGMs work great if you have dock access often and can keep the AGMs at 100%. I have met cruisers who haven't had any problems with their AGMs, but I have seen many who experienced the same issues that I did where the AGMs would quit holding about 30-40% of their charge.


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## JohnRPollard (Mar 26, 2007)

Maine Sail said:


> I think if AGM's are left topped up, like if you are on a dock regularly, they can last as long as wets but I have yet to hear of many success stories where AGM's clearly out lasted good quality deep cycle wets....


MS,

Interesting how different your experience is from ours.

We are on our 8th season with the 2xGrp31 AGMs. Seven of those seasons were on a mooring (for nine months/year), with no solar trickle charge. We have a stock 55 amp, internally regulated Hitachi alternator.

In those eight seasons, aside from a quick visual inspection, I have done absolutely NOTHING to or with the batteries.

Go figure.


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## Cruisingdad (Jul 21, 2006)

Purchased my Lifeline AGM's in 2006. No problems. However, I have a very large solar array and they generally stay fully charged. My experience is similar to John Pollards.

Brian


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## speciald (Mar 27, 2007)

Mine died (all 7 of them) after 4 years.


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## catamount (Sep 8, 2002)

I have just installed some very expensive TPPL AGM batteries. I hope they will give me good service. From what I understand, keeping them fully charged is important, but probably even more important is making sure that the charging profiles -- absorption and float voltages -- are right on the manufacturer's targets. And they like more current rather than less, so your alternator needs to be rated at at least 40% of your bank capacity, not the 25% factor that you could get away with with traditional flooded cells.

I should note that I am not a full-time live aboard cruiser, cycling the batteries every day. From what I gather, for that application, traditional flooded batteries still give the best service and value. But I think for the way I am currently using my boat, my new batteries have some distinct advantages (e.g. the high charge acceptance rate being one).


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## mitiempo (Sep 19, 2008)

As banks get larger the 40% of capacity alternator gets to be an impossibility quickly.


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## catamount (Sep 8, 2002)

mitiempo said:


> As banks get larger the 40% of capacity alternator gets to be an impossibility quickly.


Yes, but... with good AGM batteries, the bank doesn't have to be as large as it would with flooded cells, because you can draw them down deeper and charge them back up faster. I expect my 300 amp-hour bank of AGMs should give me the same or better working capacity than a 440 amp-hour bank of flooded golf-cart batteries, with a similar-sized alternator... But the number of cycles I can pull will likely not be as great...

On the charging voltages, I should point out that I am NOT using the AGM setting on my charger -- it is not supplying the appropriate voltages for my batteries. Instead, as it turns out, the Flooded setting on my particular charger happens to match the voltage expectations set by my batteries' manufacturer....


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## mitiempo (Sep 19, 2008)

If they have a shorter life than good flooded batteries at 50% discharge than I can't see how they have a longer life with a greater percentage of discharge.

As far as charging voltages, AGM and flooded are .1 volts apart on a Xantrex charger. The charger is listed as +/- .1 volt accuracy so either setting is probably good for AGM batteries. 

From the Xantrex manual:


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## Maine Sail (Jan 6, 2003)

JohnRPollard said:


> MS,
> 
> Interesting how different your experience is from ours.
> 
> ...


John,

You have certainly had excellent service life from your AGM's. Obviously there are always instances when the norm does not match a specific example or even a few.

My frustration lies in the variability and random death they seem to die. My buddy John's batteries were totally fine in October, had been running the microwave on the inverter just the week before haul out with no issues and starting the motor with no problems. When he removed them from the boat for winter storage they were at 100% SOC and topped up twice over the winter on a multi-stage charger but not left on it permanently. They basically sat at full charge disconnected from any loads until April. The batts were then re-installed and the motor would not crank, inverter went off on low volt alarm and they would not hold voltage with any load over about 5 amps. Batts were charged with the shore charger for two days, showed full and hit the start button and would not crank the engine. Batts were equalized and were still dead.

Wets have never seem to die deaths like I have seen with AGM's and it is more gradual than what I have seen. They seem random and sudden with little warning, which I find odd. Perhaps someone has an answer to why it happens this way but even Lifeline tech support was no help on this.

If I was in your shoes I'd probably buy them again if I liked them. I just know and have heard of too many folks getting short life for a lot more money and then many of them don't even take advantage of most of the benefits they offer, wrong reasons, which the OP asked about.

I've been on LOTS of boats and have only yet seen one battery mounted on its side and that was an Optima start battery. I know it happens but I have not yet witnessed it in person in large numbers like the marketing would have you believe lots of folks do to sell you on the benefit.

I came very, very close to buying a bank of Lifeline batts but when I ran the numbers, and my experiences, and how much "maintenance" I actually do to my wets (which are dumb regulated too) I found that it would not really benefit me for my type of sailing on a cost/benefit ratio. But that is me and my boat that it did not work for numbers/cycle/ Ah per sq in & $$ wise

If they had been regularly lasting 9-10 years I would have bought them in a heart beat but forums are filed with folks discussing short AGM life and the more I read the and saw the more concerned I became. hell I could have gotten the 9-10 year old bank just as you got the 8+ year one but like Vegas when I looked around at actual examples the odds seemed awfully stacked against me getting a 9-10 year bank.

I do know a guy who does take advantage of acceptance using two 150 amp alts and a massive shore side charger that runs off his generator. For him it has truly cut down on engine/gen runtime at anchor which was the exact benefit he was looking for. His bank is 4 years old and still goingf fine.. He also has nearly 400 watts of solar.

Not saying don't buy AGM's at all, just asking folks to think about why they are buying them, honestly.

For me the benefits of AGM rank in this order:

*Higher acceptance* - This is a HUGE benefit IF you can take advantage of it, most AGM owners I know don't or can't.

*Low self discharge* - This is great for boats in hot climates or on moorings. Wets can self discharge at up to 13+% per month in warm weather however I know few boaters who go a month without using the boat at all. Even in a worst case scenario, 13%, in hot weather leaves a full bank still at 87% SOC after a month. Still this can be a good benefit in certain use situations. Self discharge has never been an issue for me so would not be weighed in my own benefit analysis.

Many boaters I know with AGM's also have either solar or wind making the self discharge benefit mostly irrelevant. The majority of boaters in the US are on docks not moorings so again self discharge would be of little benefit to them. When off cruising you are using the banks daily and self discharge is again a non issue. Most boaters have a phantom load such as a bilge pump, stereo memory or LPG detector etc. so there are already loads sucking the battery down that require periodic charging anyway which would take care of any self discharge at teh same time. If you don't have solar or wind, are on a mooring, in a hot climate and rarely use your vessel this can certainly be a benefit.

*Maintenance* - I find this to be a tad over blown. I have yet to work on a vessel where it took me more than 20-30 minutes to add water to batts or check them and those are the long ones with major access issues. My own batts at 4 years old have taken water once and it took all of about 3-4 minutes.

If maintenance is the sole claimed reason for "upgrade", I know a boater who did this for that exact reason, it really is a lot of money to spend. He could have paid a pro to do the maintenance and still pocketed $400.00 to $500.00. Wet cell maintenance is over blown IMHO and experience plus for very little money one can buy hydrocaps if really concerned. My batteries are dumb regulated and reside on a rather un-sophisticated solar charge controller yet they took a very small amount of water once in four years. I honestly don't even consider that "maintenance". Just checked them last week and with my screw driver it took me all of 1 minute to glance at the water levels. Did it in June as well, 2 total minutes this summer of "maintenance".

Even if I gave the water filling a ten minute labor allowance every year, at my $70.00 hourly rate, that is $11.60 worth of labor time. I would have to add water to my batteries 61 times over their life to equal the price premium on my bank to make the move to AGM based on maintenance alone.

*Lay on side* - This is usually much more of an issue on smaller vessels than large and folks with smaller vessels usually can't afford AGM's anyway. For about $40.00 in materials one can build a battery platform on just about any vessel. I have done them on nearly every boat I have owned for far less than the premium price upgrade to a Gel or AGM battery. You still ahve to find a way to secure them so you would possibly be looking at some epoxy work anyway.

Not trying to disuade anyone, cause they can be a benefit for some. I just happen to see a lot of boaters not taking advantage of any of the "benefits" except a couple minutes saved per year on maintenance.


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## btrayfors (Aug 25, 2006)

"Wets have never seem to die deaths like I have seen with AGM's and it is more gradual than what I have seen. They seem random and sudden with little warning, which I find odd. Perhaps someone has an answer to why it happens this way but even Lifeline tech support was no help on this."

Maine...

A few years ago I raised the issue of catastrophic AGM failures with Bobby Surette of Rolls/Surette fame. He'd also heard of them, as I had, and speculated that one reason might be manufacturing defects, specifically in the rod linking the plates. Apparently, these are tack-welded during manufacture and, because of the exhorbitant metal prices at the time were being downsized by some manufacturers. A weak or improper weld could, with time and jarring, result in instant failure. This happened to a boat I know some few hundred miles from the Azores....not a good time!

I deal with AGMs for customers all the time, and with gels and flooded batteries in my own tests and boat and radio shack. I have one little AGM which has given impressive service so far: it's under the forward seat in my Caribe dingy, and powers the automatic bilge pump, a fathometer, and running lights. It's maintained by a 2x3' solar panel, and has been very good for several years now (it lives in the basement over winter).

Other than that, I'm not really impressed with AGMs, and have all flooded batteries on my boat and in my ham shack (T-105s).

Was really looking forward to the general production of the Firefly battery technology, but...... :-(

Bill


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## JohnRPollard (Mar 26, 2007)

Maine Sail said:


> ....
> 
> If I was in your shoes I'd probably buy them again if I liked them. I just know and have heard of too many folks getting short life for a lot more money and then many of them don't even take advantage of most of the benefits they offer, wrong reasons, which the OP asked about.
> 
> ...


Maine,

All good points.

One thing I have to admit, is that I haven't re-analyzed the cost-benefit since I bought our last set of AGMs. At that time, I paid what I felt was a reasonable premium over the price of wet cells. But it seems that AGMs have escalated in price since then -- contrary to what you'd expect with new technologies as time passes.

From all accounts, we're probably getting near the end of our AGMs' lifespan (although I've not detected any reduced performance). So I'll probably need to study this again. But based on our positive experience so far, I would not be inclined to switch back to wet cells. However, today I would also want to study the Odyssey batteries very carefully to see whether those might make more sense. (Correction, meant to say "Odyssey, not "Optima".)

Just another point about the mounting position. I want to mention that it is not merely that an AGM can be mounted in any position (except upside down). It is that they also do not suffer a diminished output when so mounted.

This is important to sailors, who can conceivably find themselves at high angle of heel for long periods of time -- especially long-distance voyagers. Whereas, wet cells suffer diminished output when "mounted" at an angle. So even if you can mount them flat in the static environment, you may be using them in an angled mounting position in the dynamic environment, with diminished output.

And a final note about self-discharge. This may be an attribute that some would value more than others, depending how they use the boat. I know up your way, the season is short, and folks tend to use their boats frequently during the season. So, it might be unusual for a boat to go unused for two-three-four weeks.

Down this way, we have a 9-10 month season. So there is less urgency to use the boat every chance we can. Summers are long and tremendously hot. We often don't use ours for 4-5 weeks at a stretch during peak summer heat. With no solar or wind charging, and no shore power at the mooring, low-discharge was always important to us.

This is definitely a case of "your mileage may vary".


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## btrayfors (Aug 25, 2006)

Latest news on Firefly as of Sept 14, 2010:

An Indian company, Electrotherm, is in advanced negotiations to buy Firefly patents and assume some of their debt. The deal was recently approved by the Peoria, IL county board.

Electrotherm in talks to acquire US-based Firefly

So, maybe, we'll be seeing the Oasis battery produced in India. Who knows, they may even license someone to produce them here!

What I wanna know, though, is why the hell the US govt. couldn't move fast enough to keep that operation going here? The loan was only $6 million....a paltry sum, given the billions floating around. Some Fed should really be ashamed of letting this deal get away!

Bill


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## catamount (Sep 8, 2002)

mitiempo said:


> If they have a shorter life than good flooded batteries at 50% discharge than I can't see how they have a longer life with a greater percentage of discharge.


I didn't say they have a longer life, rather I meant that I can get just as many amp-hours per charge cycle (that's what I'm calling the working capacity) out of a 300-amp-hour AGM battery as I can out of a 440-amp-hour flooded battery. They will have a shorter life, though.


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## JohnRPollard (Mar 26, 2007)

MaineSail,

Note the correction to my previous post, where I said "Optima" when I meant to say "Odyssey".

Here is the specific Odyssey Group 31 replacement battery that I am particularly curious about.

Any experiences/feedback/info? How do you feel these compare, reserve capacity-wise?


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## Gene T (May 23, 2006)

I bought an Odyssey battery for my motorcycle recently. Very expensive and charging charismatics are somewhat different. I do not believe I would use a bank of them in a boat but are good for single use. 

I have 2 cars with Optima batteries. The work good for this application. Probably ok for a bank on a boat but not something I would use. 

The boat has AGM, came with 10 of them - 8x6 volt and 2x12 volt. One of the 12v was in parallel with the one massive 880ah 6v bank, that made me nervous so I have disconnected it and am only using the 8x6v for house now and 1x12 for starting/windlass. I may parallel the extra 12v with the starting circuit (just because it is there I guess). No issues yet with the AGM - time will tell. I do not know how old they are but it is very nice not to mess with filling them. They are always clean too. 

The last boat seemed to burn up wet cells. My boats live in a marina with a battery charger on all the time. The boat will sit for weeks at a time not being used. The 2 #27 series on the last boat needed water every couple of months, seemed like a lot. Maybe used a gallon of water every couple of years. 

When the AGM need replacement I will consider all options as well as needed capacity. 

Gene


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## catamount (Sep 8, 2002)

JohnRPollard said:


> MaineSail,
> 
> Note the correction to my previous post, where I said "Optima" when I meant to say "Odyssey".
> 
> ...


John, these are the batteries I just installed -- I have a bank of three of the Odyssey PC2150's, and a smaller version for my start battery. I have only just put them in, so no long-term experience to share, but so far I'm very happy with them.

One additional thought to add to MaineSail's list of pro's and con's for AGMs -- for any vessel doing any offshore work, there is always the potential for a serious knockdown, so having a dry, sealed battery could be a safety issue.


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## JohnRPollard (Mar 26, 2007)

catamount said:


> John, these are the batteries I just installed -- I have a bank of three of the Odyssey PC2150's, and a smaller version for my start battery. I have only just put them in, so no long-term experience to share, but so far I'm very happy with them.
> 
> One additional thought to add to MaineSail's list of pro's and con's for AGMs -- for any vessel doing any offshore work, there is always the potential for a serious knockdown, so having a dry, sealed battery could be a safety issue.


Cool. Please keep us posted on how they do. Real world reports are few and far between.

Would you be willing to share the price comparison to wet cells and/or standard AGMs?


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## CalypsoP35 (Jul 24, 2006)

*Where do gels fit in?*

I see the comparisons between AGM and wet cells, but were do gels fit into the discussion?

I have had good luck with my gels. I bought my 1980 P-35 in the spring of 2002. It came with two gel batteries. I could not tell from the markings how old they were. I replaced one the summer of 2003 and I replaced the second one this year. The batteries clearly were not new when I bought the boat. The one I replaced this year had to be at least ten years old. I do not have shore power or any charging capability other than the alternator. During the summer I sail Wed nights and usually either spend a weekend on the boat or if we don't go away for the weekend I will go out for a day sail. Typically each time I leave my mooring the engine runs for about 1/2 hour each way getting in and out of our bay. And of course there are those rare days when we have to motor to or from a destination, which could mean running the engine up to 5 hrs.

I do a lousy job of taking care of my batteries. They stay on the boat at dry dock from Nov to May and I usually don't even give them a trickle charge until I'm ready launch the 1st week of May. My batteries are in a cockpit lazerette and are pain to get to. So I'm glad not to have to check the fluid. That in and of itself makes the extra cost worthwhile to me especially give how long they have lasted.


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## casioqv (Jun 15, 2009)

I've been chomping at the bit to reply in this thread, because my account hasn't worked!

I think the main reason people use AGMs in sailboats is because they're concerned about acid leaks when heeling, or during a knockdown. In reality this isn't a problem.

I use a large flooded battery bank (3 12v batteries, 315ah total) on my Catalina 22 to run an electric outboard (82lb/24v trolling motor) instead of a gasoline motor, and it works well with flooded batteries. With AGMs I would have paid much more money, and had more weight, shorter life, and less range.

I've heeled as far as 45 degrees with mine, with no acid leaking issues. In case of a knockdown, I've enclosed them inside HDPE boxes with large quantities of baking soda- so any acid that did leak would be totally neutralized. The boxes are firmly strapped to the hull with motorcycle lashing straps passing through HDPE (cutting board) blocks glued down to the hull with g/flex epoxy.

My boat sits at a mooring and gets charged at the dock through the 3 bank charger after each weekend sail, so they get stored fully charged. I've never needed to add water to them so far...

Most AGMs (like Optima blue tops) are not true deep cycle batteries (they're dual purpose marine), and don't survive deep discharge as well as flooded deep cycles. The "high cost" most people associate with AGMs isn't even for the proper ones; true deep cycle AGMs are extremely expensive.

I do use a small AGM for the electric motor on my dinghy, because that needs to lay sideways. In a major emergency on my regular boat, such as a knockdown where all acid was lost- this small AGM can act as a backup for running navigation lights, radios, etc.


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## chef2sail (Nov 27, 2007)

I am on my third year with 6-6volt Lifeline AGM without one problem

I will be the second person you have met who has not installed them flat but some one their sides. It allowed me to get 6 6volters in a space that T105 would only aloow me to get 4 6 volters. 

Another advantage which has not been mentioned and maybe this only applys to Lifeline 6 volt batteries. Their footprint is not as high as most wet cell 6 volt batteries or even reguar 12 volt ones.. In many battery storage spaces this 11/2 inch can be the difference between being able to use the 6 volt battery vs 12volt. Amp hrs wise in most instances you get double the amp hrs with 2 6 volt as opposed to 1 12 group 31volt. I use the group 31 to compare as the w and d dimensions of the two 6 volts usually is equal to 1 group 31 12 volts. 

I like the no maintainence option as well as the quality so far of these batteries, so unless I suffer a catastrophic failure next year, I would purchase them again.

Dave


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## catamount (Sep 8, 2002)

JohnRPollard said:


> Would you be willing to share the price comparison to wet cells and/or standard AGMs?


Hahahaha! Let's put it this way, they are lot less expensive than Lithium Iron Phosphate batteries.... ;-)


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## casioqv (Jun 15, 2009)

I paid $70/each for Johnson Controls flooded true deep cycle group 31 115ah (20 hour rate) batteries.

Lifeline group 31 AGMs seem to go for about $300 each and have slightly less (105ah 20 hour rate) capacity. These are dual purpose marine (not a true deep cycle battery), and won't survive deep discharge like my solid plate flooded ones will. So in reality they have roughly half the usable capacity for the same weight/size.

If cost wasn't an issue I'd still love to have the Lifeline AGMs, but can't justify paying over 4x the price for half the usable capacity!


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## JohnRPollard (Mar 26, 2007)

casioqv said:


> ...
> 
> Lifeline group 31 AGMs seem to go for about $300 each and have slightly less (105ah 20 hour rate) capacity. These are dual purpose marine (not a true deep cycle battery), and won't survive deep discharge like my solid plate flooded ones will. So in reality they have roughly half the usable capacity for the same weight/size......


That's news to me. Lifeline does offer another line of dual-purpose/starter batteries, but the AGMs in our boat are billed as true deep cycles.


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## Maine Sail (Jan 6, 2003)

chef2sail said:


> I will be the second person you have met who has not installed them flat but some one their sides. It allowed me to get 6 6volters in a space that T105 would only aloow me to get 4 6 volters.


You're actually USING the benefits of AGM's! My only point was that MOST boaters I know are not taking advantage of the many features and benefits AGM's can offer ye they are paying the premium.


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## mitiempo (Sep 19, 2008)

Last month I installed a bank of 2 Lifeline GPL-30HT on a Westsail 32. They are 150 AH each at the 20 hour rate and weigh 96 lbs each. They cost the owner just over $400 each. He swears by Lifeline as his original bank is 2 Lifelines of about 100 AH each and they are 8 years old and still doing fine. They have been relegated to a start bank with the 2 GPL30HTs as the house bank. They are described by Lifeline as true deep cycle batteries. Nice batteries but pricy.


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## casioqv (Jun 15, 2009)

JohnRPollard said:


> That's news to me. Lifeline does offer another line of dual-purpose/starter batteries, but the AGMs in our boat are billed as true deep cycles.


Which battery model are you using? I haven't actually used Lifelines, so I was just looking at the specs on their website and could only find one Group 31 model- the GPL-31T.

Perhaps I misinterpreted the data- it was advertised with a relatively high CCA rating, which usually means it's a dual purpose. Usually true deep cycles don't avertise a CCA rating at all because they're designed for low current use.

Also, to be fair Lifelines are high end batteries, and my Johnson Controls are the cheapest of cheap flooded batteries. It might be more fair to compare Trojan flooded group 31s (more like $200 each) to the lifelines.


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## mitiempo (Sep 19, 2008)

Here is Lifeline's description of the GPL-30HT


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## casioqv (Jun 15, 2009)

mitiempo said:


> Here is Lifeline's description of the GPL-30HT


I was wrong then, the lifelines are true deep cycle batteries. They just happen to publish the CCA value, which is unusual for a battery not intended for starting.

In any case, I don't think I've *ever* drained my bank below 80%, even after a week long cruise or two weeks without coming into the dock on mooring. I probably could have gotten by with a smaller bank.


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## mitiempo (Sep 19, 2008)

The Lifeline Group 31 - GPL-31T - has the same cycle specs as I posted above.


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## JohnRPollard (Mar 26, 2007)

casioqv said:


> I was wrong then, the lifelines are true deep cycle batteries. They just happen to publish the CCA value, which is unusual for a battery not intended for starting....


That is another advantage of AGMs -- while being true deep cycle, they can also provide high amperage for engine cranking without any ill effects.


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## casioqv (Jun 15, 2009)

JohnRPollard said:


> That is another advantage of AGMs -- they can also provide high amperage for cranking.


With flooded batteries high cranking amps requires a "sponge" type plate which doesn't survive deep discharge well, whereas true deep cycles use solid lead. So there's a serious tradeoff between CCA and longevity, but I don't know if the same applies to AGMs. Anyone know?

Since I use the battery bank for propulsion (electric trolling motor) and carry no engine, I wouldn't want my batteries made with any sacrifices for cranking amps.

But I think it makes sense if you have an electric start engine to make sure all of your batteries aboard could start the engine in a pinch, and not just the dedicated starting battery.

Still, I'm pretty sure a flooded deep cycle group 31 would have no problem cranking over a typical small diesel in a sailboat.


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## hellosailor (Apr 11, 2006)

" They just happen to publish the CCA value, which is unusual for a battery not intended for starting."
I had a discussion with someone at JCI (who make Optima and about 1/3 of the rest of the batteries sold in the US) about SLI versus deep cycle batteries for mixed use. Bottom line is that a relatively thin plate SLI battery will be ruined by just a few deep discharges, but a thickplate deep cycle battery really doesn't care. As long as it is capable of putting out the impulse current needed by your starter--it can be used as a starting battery with absolutely no drawbacks.
And since it is relatively easy to buy more deep cycle amps than a relatively small starter motor will need, why not? If the guy on the bow is close enough to hear the guy on the helm, the odds are that starter motor is still "small" compared to real industrial motors and starters.


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## Maine Sail (Jan 6, 2003)

mitiempo said:


> Here is Lifeline's description of the GPL-30HT


None of the boaters I know up here EVER hit 1100 cycles to 50%. Even if they did 60 nights per season which is highly unlikely, recreationally, it would take 18 years to hit 1100 cycles. I've yet to hear of any AGM breaking the ten year mark up this way let alone 18...


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## casioqv (Jun 15, 2009)

Maine Sail said:


> None of the boaters I know up here EVER hit 1100 cycles to 50%. Even if they did 60 nights per season which is highly unlikely, recreationally, it would take 18 years to hit 1100 cycles. I've yet to hear of any AGM breaking the ten year mark up this way let alone 18...


I'm guessing these specs are in "laboratory conditions" with one consecutive cycle after another on a digital smart-charger in a temperature controlled room. Not sitting for months at low charge levels between cycles in 100F+ temps, and then charging with a fixed voltage alternator as most marine batteries are treated.


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## mitiempo (Sep 19, 2008)

Maine - don't shoot me, I'm just the messenger. 

It does seen a bit high to me as well. But their description is "deep cycle" which is why I posted it. On the other hand they probably meet those cycles under some conditions as it is published.

For comparison here are Trojan's published specs for cycling. Note that the T105 is rated for more cycles (754) than any other 6 volt Trojan and double or better than any 12 volt Trojan except for two. Whatever the conditions under which they meet these numbers it is the comparison that is the most interesting. It is also interesting that Trojan publishes a different number of cycles for each battery, which seems a bit more honest than Lifeline's published cycle life which is the same for every deep cycle battery they make, including the 2 volts.

If we can assume that both Trojan and Lifeline are testing under the same conditions it means to me that the T105, when price is considered, is a much better value per cycle than an equivalent Lifeline battery. There are still the other advantages of AGM batteries to consider of course.


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## btrayfors (Aug 25, 2006)

mitiempo said:


> Here is Lifeline's description of the GPL-30HT


.... "500 cycles to 100% depth of discharge"

While Lifeline batteries have some strong proponents, I just don't believe this claim. These have to be miracle batteries. Of course, they don't say how much *capacity* remains after such torture. Maybe they're quoting the number of cycles before the battery physically blows apart 

Hidden deep in the table presented by mitiempo are some interesting statistics which are of more real-world utility, particularly when sizing a battery bank.

Note that the available amp-hours (AH) depends on the *rate of discharge*. This is the basis of Peukert's equation, i.e., higher discharge rates take more out of the battery than expected, while lower discharge rates take less. It's the underlying basis for the current "best practice" of having a single large house battery bank, rather than splitting batteries into multiple banks.

Let's take the case of the venerable T-105. It's rated at 225AH @ the 20-hour discharge rate (average rate of discharge of about 11.25 amps).

However, at a greater rate of discharge, the 6-hour or approx. 31.5 amps, it will only deliver 189AH. More to the interest of cruising sailors, if you discharge at a slower rate, say the 100 hour rate (approx. 2.5 amps), you get a total of 250AH from the same battery.

Now, let's put these figures to use on a cruising sailboat. The typical cruising sailboat in the 40-foot range draws something like 150-200AH per day on average. Let's say, 175AH, or about 7.3A average draw over each 24-hour period. *Now, if such a boat were to have six T-105s in series/parallel (675AH at the 20-hour rate and 750AH at the 100-hour rate), it would be drawing each battery in the bank down at a bit less than the 100-hour rate, and would therefore enjoy the benefit of more AH available than the 20-hour rated amount.*

In a 24-hour period the usage would be 175AH of a 750AH capacity (100-hour rate), or about 23% of total capacity. That would seem to be a comfortable load for the house batteries, and one which would prolong their life over, say, a drawdown to 50% capacity or higher.

In real life the numbers work out. For many years I had only 4 T-105's, yielding a capacity of 450AH @ the 20-hour rate. While this worked OK, I felt it was a bit tight, since I draw something like 175AH per day, with refrigeration, computer, radios, autopilot, radar, etc., etc. After I added two more T-105s, bringing the total house bank to 675AH at the 20-hour rate, it felt much more comfortable, and I believe that is the correct size for my boat and the type of sailing I do.

It would seem that, for the present at least, Mr. Peukert and I have come to a sort of agreement....he gets to play as usual and I get to reap the benefits of his effect by choosing the right size house battery bank 

Bill


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## mitiempo (Sep 19, 2008)

Bill
As I added to my post above, Lifeline states the same cycle life for every deep cycle battery they produce, even their 2 volt batteries. Trojan on the other hand publishes stats to show that the T105 will last twice as many cycles as some other Trojan deep cycle batteries. Trojan's published cycle life certainly seems more realistic than Lifeline's numbers.


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## chef2sail (Nov 27, 2007)

I had the same experience as you btrays with the size of my bank...thats one of the reasons I choose 6-6 volts lifelines. I also reinsulkated the refrigerator to cut down on my "electrical diet"

60 nights on a sailboat a lot. Again that might be a lot in Maine or the NE but not here. We have averaged over 100 nights a year or more for many years. We utilize it every weekend starting out on Friday evenings with a three week trip every year. A lot of owner her in the Chessie and south of here get the advantage of leaving their boats in for 10 months and get more usage. They use their boats like we do

I agree with Mainsail that there are a lot of AGM owners whose usage and reasons for buying them doesnt fit or isnt necessary for their actual usage and i think that was the point he was trying to make. Whats is the use of spending the extra money if you cant charge them properly etc.

Their are many items people buy things which really dont match up with their needs in real life. Off road SUV,s, 9 hp engines on dingys for people who basically use them to putter around, expensive premium high tech sails for non performance boats and non racers, huge powerfull electric windlasses on 40 foot or less cruising boats which break down and can be finicky while a good mechanical one never does. Many people feel large chartplotters are a waste since they make paper charts (All should know how to use these). and on and on.

Its hard to generalize for a whole industry that these AGMs are a waste, as I am sure that many of us who have them swear by them as much as the ones who refuse to buy them think they are a waste of money.

We all have items/ gagets on our boats which maybe dont match up with our needs or usage. LED Lanterns...Solar stern lights,,,,toasters to use on the propane stove... are a few of mine.

It makes sense to me that the technology of an AGM is consistant with my needs and usage. It is one of the gagets I have decided to spend my "waste money on".

Dave


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## davidpm (Oct 22, 2007)

chef2sail said:


> It makes sense to me that the technology of an AGM is consistant with my needs and usage. It is one of the gagets I have decided to spend my "waste money on".
> 
> Dave


Dave would you mind sharing some of the details:
What batteries do you have?
What is total amp-hour rating?
Total daily usage?
Charging configuration, smart, dumb, size
How do you charge? Shore, alternator, both.
What did you use to have, how long did they last?
How old is your current setup.

There may be a pattern emerging.
If you are away from the dock more that 40 nights a year
If you have a high-capacity smart alternator setup.
You get to a dock and fully charge at least once a month.
You are lucky and don't get battery that has a plate come loose after 3 years.
You are willing to spend 1,000 extra for batteries and maybe another 2,000 for alternators, smart chargers etc.
You can expect to get 6 years plus from your AGM's and have the advantage of running the engine for one hour per day instead of 2.

Dave, I know my summary above is not exactly correct so if you could give details of your usage and configuration and costs maybe the real pattern can be nailed down.
The AGM's have to be good for someone.


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## mitiempo (Sep 19, 2008)

David
Lifeline does well.


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## killarney_sailor (May 4, 2006)

Gee, you would think that we are discussing anchors or guns here - such passion. I have AGMs because two of the 4Ds are under the other two and checking water levels would be a major pain. This is the first experience I have had with AGMs and I am pleased so far but would not be adverse to flooded if I did not have accessibility issues.


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## sidmon (Aug 2, 2009)

I have AGMs because the PO had added a second battery bank under a salon settee...Didn't/dont want H2SO4 venting under there....

Bought them (2 group 31s-changed the starter bank at the same time to 2 grp 24s...one of which I can isolate out as a spare) when on sale at WM...

For the record, charging is primarily by a 20 amp Guest 2622A. As such, I have not opted to reconfigure the original alternator on my '84 2GMF...Which so far has shown no ill effects to either it or to the batteries. 

FWIW...This setup and expense works for me.


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## mitiempo (Sep 19, 2008)

An alternator with a dumb regulator as all standard egines have should not have an issue because it never works hard.


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## donradclife (May 19, 2007)

I had chat with the Lifeline salesman at the Newport boat show yesterday. He just fininshed telling the guy before me that Lifeline owners were reporting good performance for over 10 years, etc....

I said that I lived on the hook. He asked how often I went to a marina where I could equalize. I said maybe once or twice a year. He said that unless I brought the Lifeline batteries up to full charge on a daily basis or equalized them frequently they would sulfate and I could only expect about 3 years.

This is why I'm using gels.


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## Maine Sail (Jan 6, 2003)

mitiempo said:


> An alternator with a dumb regulator as all standard egines have should not have an issue because it never works hard.


Brain,

Care to expand on this...


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## mitiempo (Sep 19, 2008)

Wouldn't it taper off fairly quickly without a 3 stage regulator? Or would it max out as long as the batteries will accept current? And if it does give maximum output as long as the batteries will accept it what advantage would a 3 stage reg have?


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## sidmon (Aug 2, 2009)

mitiempo said:


> Wouldn't it taper off fairly quickly without a 3 stage regulator? Or would it max out as long as the batteries will accept current?


There are threads on here that went round and round about this. I was worried the old 30 amp internal Hitachi regulator would fry in short order trying to meet the AGMs' acceptance rate (at which time I could have justified the bigger alternator with smart regulator costs to "The Admiral"  ).

But -so far- I have had no ill effects. That said, I don't deep draw on the house bank and just use engine charge to replinish it on a routine basis.

As for equalization...I believe there was a contentious thread on here some time back about that.

Seems the eventual consensus was it depended on the make of battery.

Edit:

Here is that thread:

http://www.sailnet.com/forums/island-packet/18498-equalizing-agm-batteries.html


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## Maine Sail (Jan 6, 2003)

mitiempo said:


> Wouldn't it taper off fairly quickly without a 3 stage regulator? Or would it max out as long as the batteries will accept current? And if it does give maximum output as long as the batteries will accept it what advantage would a 3 stage reg have?


Brian,

The idea that a dumb regulator tapers a charge was fed to us by the multi-stage regulator folks. It does not it only pushes a voltage and strives to get to that voltage.

Of course when they fed this to us many marine alts came through with a fixed voltage set point of 13.8v so the "tapering" moniker had some truth to it but not because it actually tapers off the charge but because you need more than 13.8 volts to get an effective charge beyond about 75-85% SOC.. With a max output of 13.8 it makes it very, very tough to ever get a full charge hence the term "dumb" regulator.

Fast forward to today's marine alts. These days nearly every regulator on a marine alt, even the exact replacements for the old one that may have been 13.8 volts, are now almost always 14.2-14.6v regulators.

I think the graph below sums up my feelings if you really look closely at it and digest it. This graph is from a Practical Sailor head to head comparing external voltage regulators to a "dumb" regulator set at 13.8. A rather unfair comparison IMHO and one that only served to further the idea that external regulation is always necessary for a sail boat.

Yes, SOME alternators from the 70's and into the 80's came with 13.8 volt outputs. Most current alts, including the replacements for these exact alternators, now ship with target voltages of 14.2-14.6 V not the dreaded 13.8 volts.

We all know 13.8 will undercharge batteries but a standard dumb regulator will put out the same amps as "smart" regulator up until the batteries hit the target of 13.8 volts then the smart regulators will continue to charge faster until they hit their voltage set point of 14.2-14.6. Again, comparing 13.8 volts of "pressure" to 14.4 or 14.6 is a totally unfair comparison but one that external regulator companies have capitalized upon.

If the "dumb" regulator had been set to 14.2-14.4 in this test the graph would have been nearly identical just as it had been until the batteries reached 13.8 which is where the graph bears off between dumb and smart.

All of the currently marketed external regulators are CV or constant voltage driven NOT CC or constant current. Until the batteries reach the regulators set point voltage the alt is putting out max accepted amps or the limit of the alternator which ever comes first. The dumb & the smart regulators have no idea what the alt is putting out for amps, they are not constant current driven, it is only looking for voltage at the batteries. If a "dumb" regulator is sensing a bank not yet at the "set voltage" it is essentially "open" and applying what the alt can supply or the batteries will accept.

Once the batteries get to 14.2 to 14.4 the batteries are now really tapering off their acceptance. Batteries by nature accept less and less as they fill until they accept as little as .5-2% of capacity. AGM's accept more than Gels' and Gels' accept more than wets but they all taper their acceptance when they get into the 80+% or more SOC range.

If you pushed the set voltage (read pressure) to 15+ you could increase accepted amps slightly but at a potential cost to the battery. This is why it is usually only done during the occasional equalization.










Most knowledgeable boaters cycle their batteries between 50 & 80% state of charge when cruising away from the dock and this graph shows very, very clearly that up until the batteries hit 13.8 volts, at around 78% SOC, ALL the regulators performed basically identically from 55+/-% SOC to 78% +/- SOC. As I said if the "dumb" regulator was set to the same voltage/pressure as the "smart" ones the curve would have been virtually identical. The only real feature you loose is a float setting and temp sensing.

If you were going to switch to AGM's or Gel's I would highly urge an upgrade to external regulation.

I bought and converted an alternator for use with an AGM bank I almost bought but never did. It is still sitting in my barn ready to be installed. I have TWO "smart" regulators to choose from when and if I decide to install it, I see no need, for my current wet battery bank and use, to upgrade to "smart" regulation on my wet cell bank even though it is free, ready to go and sitting in my barn.

My "dumb regulated" stock Mitsubishi alternator puts out 14.4 volts and fed a bank of Wal*Mart batteries for my buddy who owned the boat before me. He and his wife crusied if for five straight years of 90% on the hook cruising. They ran the engine just over 2700 hours during that time and the bank was still performing well at year six when I bought the vessel. I know it may be a shock that a "dumb" alternator charged a set of Wal*Mart batteries for the coastal cruiser equivalent of 27 years worth of engine run time over a five year 24/7/365 cruise but it is true. That same dumb alt is still chargin my battery bank and doing just fine.

Despite my "dumb" alternator supposedly "cooking" my batts I have added water to them once in four years. I can also trigger the re-set of my battery meter, on long engine runs, to 100%.

Multi-Stage regulation HAS benefits don't get me wrong, I just think those benefits are a little over hyped for the average coastal cruiser using wet cell batteries and "weekending".

*If you have AGM batteries - a multi stage regulator with temp sensing for both the alt and batteries is a good idea.

*If you have GEL batteries - a multi stage regulator with temp sensing for both the alt and batteries is a good idea.

*If you have a LARGE bank of batteries and the alt is considerably smaller than the acceptance rate of the bank (wet, AGM or GEL) a multi stage regulator with temp sensing of at least the alt is a very good idea.

Note: Temp sensors are notorious for not being accurate or working when you really need them this is why I like the Balmar MC-612 as you can limit the output fairly simply as well as having the temp sensors..

I have seen a fair number of dumb regulated alts cooked by large banks of AGM batts, but any large bank of wets could also cook them too. The problem becomes that the 55 amp alternator that was more than adequate for the 200 Ah wet bank, that had a max acceptance of about 50 amps, becomes an alt run at wide open throttle feeding the same size bank of AGM batts and it eventually cooks its self to death. I have seen paint burned right off the alt case. One of these boats cooked the alt twice. The same alt was converted to external regulation with temp sensing and is still going today many years later.

Like anything it comes down to what you have and what you want to do. I have actually had the opportunity to A/B the same alternator with both dumb and smart regulators on one of my boats. This was due to a failure of one of the Balmar regulators which required me to re-install the "dumb" regulator. Getting back to 90% SOC from about 55% SOC saw basically a non discernible difference and one that would mirror the PS graph above had that "dumb" alt been pushed to the same voltage as the "smart" ones.

Many people also upgrade the alt at the same time as the regulator so the actually benefit of more charging amps is usually coming from the larger alt rather than the regulator. Sterling, a European manufacturer, likes to push the voltage so he can show " faster charging". This faster charging admittedly, says so right in the manual, requires more battery maintenance. Balmar & Ample prefer to stick with lower, safer voltages.

*I love this quote by Balmar:*

Quote:

 Originally Posted by *Balmar* 
_ Forget the rumor that an oversized alternator will destroy your batteries ... *the truth is that the acceptance rate of your batteries will dictate how much amperage the alternator will provide.*_

 They just said what I took an entire page to write....


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## mitiempo (Sep 19, 2008)

Maine
Thanks for the explanation. I have been spending some time today on Ample Power's site going over this as well. 
I also like the Quote from Balmar.

My problem will be the 3rd * example you give. I have a Yanmar YSE8 with I believe the standard 25 amp alt. At a minimum I will have 225 AH of wet cells and maybe 4 for a total of 450 AH. I haven't a hope in hell of charging them with my alt nor would upgrading the alt make sense with only 8 hp at my disposal as I don't think it could turn anything much bigger. My best hope for long term maintenance of a bank this large is probably solar with a good MPPT controller. And being as efficient as possible in energy use. And as you have shown the regulator really won't make much difference in a 50% to 80% charging scenario in any case. The only benefit I could gain is temp sensing to protect my puny alt.


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## Maine Sail (Jan 6, 2003)

mitiempo said:


> The only benefit I could gain is temp sensing to protect my puny alt.


That alt is available in 50+/- amp versions and I have used them on the one lunger Yanmar's before with little issue. They can bog the engine a little though. You could still use an MC-612 and run it in small engine mode so the alt is not running at near max. Doing so should yield a longer life for the alt.


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## JohnRPollard (Mar 26, 2007)

The first time we switched to AGMs was on our previous boat, a Dana 24. 

The alternator and or voltage regulator had died, so I decided to go forward with a complete charging upgrade. 

-Switched batteries from 2xGrp24 wet cells, to 2xGrp31 AGM
-Switched alternator from stock 55 amp Hitachi with internal regulation, to high-output Balmar 80 amp with external regulation
-Added Balmar MC-612 external smart regulator, with optional temp sensing at battery and alternator
-New wiring harness, Zapstop, etc
-Switched from old 10 amp dumb charger to 20 amp Statpower Smartcharger

That was a nice set-up, although very $$$. But it was precipitated by the failure of the charging system and dead batteries.

On our current boat, the newish 2xGrp27 gel batteries were not holding a charge very well. But everything else in the system seemed to be working fine. So we stuck with the stock 55 amp internally regulated Hitachi, and just swapped batteries to 2xGrp31 AGMs. At the time, it cost us about $200 more for those batteries than it would have for the wet cells.

This arrangement has worked well for us for eight seasons -- most of them spent on a mooring with no charging. Our "dumb" alternator regulator appears to be set in the 14.2 volt range -- which I suspect explains why the previous gel batteries did not hold up well, and also why the AGMs have done fine.


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## mitiempo (Sep 19, 2008)

Thanks Maine.


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## btrayfors (Aug 25, 2006)

Brian,

Ditto to what Maine said.

If you do choose to go with the Balmar MC-612 MaxCharge regulator -- which I also highly recommend -- it has two ways to limit charging output:

1. you can just flip a switch and cut to 50% power out...just a small SPST switch and two wires to connect to the regulator; and/or

2. you can set the output to any desired percentage of the alternator's capacity, thereby derating or limiting it's output.

This latter mode works very well if you (like me) don't trust temperature sensors and/or if you're using an oversized alternator intentionally, and are de-rating it to be sure it doesn't overheat.

This last is a very good strategy. For example, on a boat which will handle a 100A alternator with a single 1/2" belt, get a 120 or 130A alternator and de-rate it to, say, 80 or 90 amps. This should prolong it's life. And, the 1/2 power switch still works, so at the flip of a switch you could cut the maximum power output to 40 or 45 amps. Like if you're clawing off a lee shore under power (who does that any more, anyway?).

Bill


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## mitiempo (Sep 19, 2008)

Thanks Bill
I have downloaded the MC-612 manual for studying and noticed the percentage reduction option.


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## SimonV (Jul 6, 2006)

Timely thread as I need new Bats, I did found this PDF relating to AGM - GEL.
Now I am even more confused!!!!!!
www.batterybook.com/GELvsAGM.pdf


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## JohnRPollard (Mar 26, 2007)

mitiempo said:


> Thanks Bill
> I have downloaded the MC-612 manual for studying and noticed the percentage reduction option.


Brian, The easy way to do this is to place a switch in the alt temp sensor circuit. Throwing the switch simulates the signal that would tell regulator to go to half power to avoid overheating the alt.



SimonV said:


> Timely thread as I need new Bats, I did found this PDF relating to AGM - GEL.
> Now I am even more confused!!!!!!
> www.batterybook.com/GELvsAGM.pdf


Hi Simon,

Gels are good batteries too. The reason I'm not such a big fan is that they require a very particular charging voltage (lower). Depending what level the voltage is regulated at, with gels you may need to make a change to the regulator.

Whereas, with AGMs you can swap them in place of wet cells, and just use the same "dumb" charging profile/voltage without any additional cost.


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## SimonV (Jul 6, 2006)

Hi John, all my bats are gell and 6+ years old all my charging regs ar set for Gells.


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## JohnRPollard (Mar 26, 2007)

SimonV said:


> Hi John, all my bats are gell and 6+ years old all my charging regs ar set for Gells.


Ahhh, then you're good to go. What is the charging voltage set at for your gels?

In my case, we had gels before the AGMs (installed by previous owner). They were only a few years old when they stopped taking/holding a charge. I don't think they liked the 14.2 volts from our stock alternator.


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## chriswgardner (May 8, 2012)

Hi John,

This is my first post to SailNet forum, so forgive me if I'm not completely up to speed on the acceptable protocols for sharing and attaining information. This conversation thread ended over 18 months ago now, but it caught my eye since I am in the process of replacing my battery bank and charging system, and your particular experience with AGMs and your particular charging set-up is almost precisely what I'm in the process of installing for this sailing season:

- dual 100 ah AGMs (group 31)
- GUEST 2622A 20 amp dual (10/10) 3-stage battery charger
- my stock Hitachi 55A alternator with internal "dumb" regulator

I have several concerns, based on the conversation that had taken place in this thread:

Someone posted that your shore-power charging system should be 40% of the AGM ah capacity, and obviously I'm about a quarter of that capacity (10 amps for each battery). Is this only to take advantage of faster charging rates that AGMs accept, or is it because it will fry my brand new GUEST battery charger that can only deliver 10 amps per battery? If it's a matter of charging time, then I'm less concerned since I'm a weekend sailer and have no issue docking to shore power and letting it charge for a whole day (or days). But if there are other repercussions of an undersized battery charger, then I'd like to know that. Frankly, I haven't come across many 40 amp chargers in my research, and incidentally, I bought this GUEST model because it was the correct rating for batteries up to 120 ah capacity, but it didn't specifically mention any special demands of AGM's. Also, this GUEST model's 3-stage charging profile seemed to fit the profile needed for AGM (and with a "finishing" rate of 14.3V seemed to be slightly on the high side for gels, but fine for AGMs which is why I went AGM).

Regarding external regulation, I originally thought I'd install a Balmar ARS-5 regulator, until I realized that the stock Hitachi 55A alternator has internal regulation. So, my concern with using the stock alternator was whether it would either cook the AGMs (not likely since it's hot amp output is not nearly enough to satisfy the acceptance rate of the 100ah AGMs), or more likely, would it wear out my alternator trying to keep up with the acceptance rate AGMs. However, I was instantly relieved that you are using my exact alternator for your 2 Group 31 AGMs, and you didn't indicate any failures of either your Hitachi or your AGMs in 8 years (and counting?). You mentioned that you thought the Hitachi 55A charge rate attempts to hold around 14.2V, which I just didn't know if I'd cook already fully-charged AGMs if I'm motoring away from dock for any length of time.

Finally, I chose AGM because I thought as mostly a weekend sailer, I'll maintain the AGMs topped off with shore power the vast majority of the time, and for that reason I expect to get many seasons out of them (you had 8 seasons with yours), but the same could be said for flooded cell batteries. However, the uniqueness of AGMs for me was it's very low discharge rate (I've read only 0.1% per day), and I'm thinking it would be just fine for me to fully charge and then unhook the batteries and leave them over the entire 6-month Minnesota offseason with only about a 20% total discharge. (You see, I'm lazy and don't want to haul out 140 pounds of batteries at the end of each season, but just want to unhook and leave them there). I also thought AGM because I had a split case on my current flooded batteries that spilled sulfuric acid all over the place, and it pissed me off enough to do the extended research on sealed battery solutions.

Anyway, my planned set-up seemed so much like yours that I just wanted to know if you've had any second thoughts about your set-up that I should be aware before I complete this entire endeavor for this sailing season.

Thanks!


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## Cruisingdad (Jul 21, 2006)

Hey CHris,

John is going to be away for a while. Just wanted you to know so when you dont get a response.

Brian


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## mitiempo (Sep 19, 2008)

Chris

Welcome to Sailnet

You shouldn't have a problem due to the small size of your batteries -it's a large bank of agm's that put a real strain on the alternator as it can run full out for hours, which it isn't designed for.

Shore chargers, at least in my experience, don't have many problems running long term at high output. But 10 amps is pretty small. There are many chargers with higher output - Xantrex in 20,40, and 60 amp 
Truecharge Battery Charger | Truecharge2 20A, 40A, 60A | Xantrex

Sterling Procharge Ultra up to 60 amp
Truecharge Battery Charger | Truecharge2 20A, 40A, 60A | Xantrex

Others include Victron, Promariner, and Mastervolt.

A better choice than the guest charger I think would be a charger that doesn't split the output evenly. Many 20 amp chargers will put the current where it is needed. For example a start battery is seldom down more than 1 or 2 AH and in that case many chargers can supply the bulk of their current where it is needed most, the house battery.


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## chriswgardner (May 8, 2012)

Thanks very much, Brian, for the timely response and very good advise. Much appreciated!


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## SanDiegoChip (Jun 12, 2007)

mitiempo said:


> If they have a shorter life than good flooded batteries at 50% discharge than I can't see how they have a longer life with a greater percentage of discharge.
> 
> As far as charging voltages, AGM and flooded are .1 volts apart on a Xantrex charger. The charger is listed as +/- .1 volt accuracy so either setting is probably good for AGM batteries.
> 
> From the Xantrex manual:


 We are considering replacing our four 6 volt batteries soon. We are leaving for cruising in October. Our batteries are not used much as we have shore power now. Our refer runs off 120volt at the dock when shore power is connected.

Our wet cells seem to take a lot of water and are a pain. They are under our settee and give off gas which we do not seem to smell but do not like the idea. They were with the boat when we bout it 4 years ago.

Will water maker water work in the wet cell batteries?

$$ is the issue here or us plus the gassing and maintenance. 
It seems every couple months we need to dig under the sattee to add water and the gassing will wreck the connections on the buses we have by them, lack of space for other placement.
We have 485 watts of solar with a Blue Seas controller that multiplies that further.

We have a Air Breeze wind generator.
 We have duel 100 amp alternators on our 38hp Beat engine.
 We are installing a smart controller for the alternators.
 We do not run a microwave or a hair dryer or anything like that.
I do use a CPAP breathing machine at night that will run off the batteries each night. It will suck up some AMPS.
We do have electronics for navigation or say anchor alarm when needed.
Most of our lights are now LED.
 We will be getting a Spectrum 6gph water maker and hope to run it off the batteries at mid-day every couple days.
We have a Xantrx 2000 charger inverter not a pure sin wave.
 We have a Xantrax Link 2000 battery monitor. At present we have a AGM
battery for our starting battery and rarely use it. It seems to work fine. It has a trickle charge hooked to it.
 So we are wondering if the charger would work with the two different battery types?
I of course need to find out the specs on our AGM battery.

Also would the Link 2000 work on the two different types? I guess if the specs were close enough. At present it is on connected to the house wet cell bank.

So I guess there is no real answers here but if we want to spend the money we get the AGM's but if we use the batteries a lot and in Mexico south on the Pacific side would not adding water be a regular chore each month?

I have noticed with two AGM 6 volt batteries we could get 660 AMP hours I think. They would fit in the space we have. They would not eat at the bus or shunt connections etc.

Would say four Trogon's get us to the same place? We have seen battery caps that do not let much gas out, recycle the gases back to the batteries, that may work for us also?

This post is confusing but that is because we are confused as to the best path for us is. We would like to save the cash but do not want to see out electrical componets get wrecked. We do not mind so much the watering but do mind the gasing. Amp hours is not clear for our needs but for the wter maker it seems they should be high.








Older picture but you get the idea.
Thanks,
Chip


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## Cruisingdad (Jul 21, 2006)

I have done both and think for a cruising boat, AGM's or very high quality (Rolls) wets are teh way to go.

You will need to change your charge rate on the charger to match AGM's. They are different float/accept/Bulk. I also have a large solar bank. Nice thing about agm's is not just the maintenance (which is very nice), but they have a very low discharge rate compared to wets. They will also accept a charge faster. 

Negatives are the cost and that they can be sensitive to poor charges. A good charger fixes this. Contrary to popular opinion, you CAN equalize agm's and is worth putting in a period maintenance schedule. But check with your mfg first. 

I personally went with Lifelines. I have no complaint except the cost. 

It has been said that AGM's will last longer. I find that suspect. I bet when it is all said and done, a high quality wet will last as long or longer. Because of access issues, I will go back with AGM's. However, if I had good access, I personally would seriously look at a high quality wet.

Yes on the battery caps.

Yes, Link should work. Check the documentation on the Xantrex charger, but unless it is a really old model, it should be able to be modified to AGMs. I have a Xantrex Prosine 2.0 and it is awesome. 

Hairdryers and stuff should be no big deal. If you actually want to save electricity, it is the coffee pot that is a killer. Get a coffee pot that has a carrafe and no hot burner after brew. THe other stuff doesn't run long enough to worry about it.

No way I would go cruising without a Microwave, especially in the tropics. It was critical to us. Relatively low power use, cooks quickly, doesn't heat up cabinm, doesn't use up propane, and a very cheap piece of equipment. I am also a big advocate of grilling (no smart arse comments from the SN'ers). It gets the heat out of the cabin and is great for things that stink. You will not want to carry those crappy green bottles around (and may not find them anyways) so go to Lowes/Hdepot and for $10-15 get a converter to run off a standard propane tank. Will pay for itself about teh third bottle too. Carry a spare of the lines. They will fowl in the salt water eventually. 

Hmmm... what else can I answer?

Brian


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## mitiempo (Sep 19, 2008)

Chip

Lifeline are the only manufacturer that recommends equalizing AGM batteries. If you get Lifelines - probably the best - you will have to set the charger to flooded battery mode to equalize - it is not active for gel or agm settings.

Make sure you have temp sensors for both the alternators and the batteries if you go with agm's.

Your buses should be fine near the flooded batteries. I wouldn't want a charger or inverter there though.


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