Not enough information.

solutions:

re locate one bank to be close to the other
replace one bank with a small new one for starting (sealed which do not need a battery box)
charge only main (large) bank from alternator etc. Use echo charge to charge start bank

 

Two separate BMs is best, recommend SmartGauge.

Victron has central display/comms units GX Colour is one, can tie in to multiple BMV-712


Single BMs using multiple shunts are rare.

Bruce @ OceanPlanet was testing one, but not very accurate?

Bogart Pentametric is a good one, but maybe not designed for marine use?

Maybe Maretron?

 

The Balmar Smart Gauge monitors the house bank and the start battery, although it only gives a voltage reading for the start battery. Which for me is good enough. And there is no shunt involved....just a matter of wiring the smart gauge to the batteries.

 

The Balmar SG200 with an extra “Smart Shunt” can do what you want..

 

Andy and Maine Sail,
It looks like the Balmar is exactly the kind of thing I am looking for. By getting an extra Smartshunt, I can monitor my windlass battery which is far away from my house bank. Thanks so much for chiming in.

Has anyone else experience with Balmar? Opinions?

For anyone interested, here is a link to the monitor on the Balmar webpage.

http://www.balmar.net/sg200-battery-monitor/

Terry

 

This
https://search.defender.com/?SI=ef1...150~204150~Optima+Bluetop+Optima+Spiral+Cell+Dual+Purpose+Marine+Battery~299.99
is $300 and you can use the monitor you have by placing the new batt close the the house bank. It's hardly more money than the Balmar...

 

I have a Link 20 and I find it is probably accurate for amperage and voltage readings. AHs used / left and so an are simply unreliable.

 

John16ct,
Thanks much for the follow up on the SG200, the links to the other posts were very informative. I didn’t realize there was a holy war on battery monitoring going on, especially with the trawler folks. I do have reservations about the SG200, because I’m most interested in seeing AH in and out for the solar system I’m installing. Frankly, the cost of the SG200 plus the extra smart shunt puts it in the range of just buying two of the Victron monitors. Being a real-time control guy in my early career, I do like the newer, learning tech in the SG200. It seems it would be pretty simple for Balmar to update the software to provide that information as well considering they are measuring it with the shunt. If it did both, I’d buy it.

SanderO,
The battery is for my windlass and lives admidships for cable length reasons and is a good 12 feet away from my house bank. It isn’t feasible to relocate it.

Terry

 

John16ct,

SanderO,
The battery is for my windlass and lives admidships for cable length reasons and is a good 12 feet away from my house bank. It isn't feasible to relocate it.

Terry

Terry,
Have you considered or is it possible to use heavier wiring for the windlass and skip the designated windlass battery?

My engine is on and had a high output alternator when I am using the windlass. Windlass draws can be significant. However I use the windlass to basically take the slack / catenary out of the chain and this imparts forward motion to the anchor. The windlass doesn't drain the batts very much as the alternator is pumping amps into the batts. I do NOT have a windlass battery but instead have 2 8Ds and use 2/0 cable to the bow from the house batt.

One has to make a cost benefit analysis when putting together an electrical system for a yacht. My dual battery monitor wiring is simple... my windlass wiring is simple. I use a high output alternator because it does the job quicker. The weight is probably less with the 2/0 wiring and evenly distributed low in the bilge along the CL. I don't need a battery box taking up real estate which needs access... and I charge on bank. The start bank is small and on an echo charge. I don't have to fiddle with battery switches either.

Of course when you have committed to an one approach changing may not be feasible. I did a complete re do some years ago.

 

Yes if at all possible, a super heavy pair of wires is a better design than separate banks.

But sometimes it is just not possible.

 

My charger control panel (Magnum) has an amp hour counter and tries to tell me when the bank is full at 100% SOC. It's totally useless. I know the settings are correct, at least to the extent it allows things to be set. I know it's not correct, because it can be showing, via a shunt, that the bank is still taking charge in Acceptance of 2+% of capacity (maybe more, as I can only estimate what degraded capacity is) and it claims the bank is at 100% SOC. I understand it's simply counting amps out and amps in. It's even supposed to reset itself and account for degredation, over time. I totally ignore it.

The only thing I find useful from the amp counter is seeing charge acceptance to know I'm really fully charged and seeing what loads are on the bank in the moment. I'm not even convinced I can really tell when I'm close to 50% SOC.

 

What to do???

So you have the latest and greatest monitor... which is telling you what the state of your batts are... how many hours left to x% of discharge... or how many you're consuming amps and so on while you go about normal activities on board.

What do you do? Do you shut down things which are drawing loads? Instruments? Lighting? Do run a genset or an the engine? Do you order new stuff which draws fewer amps? Do you order more or higher output solar panels? A wind gen? Do you look for some fault in your gear or wiring? Or even the monitor itself? Do you buy bigger batteries? or add more in parallel?

What do you do with the information your monitor is providing?

I am not suggesting that this information has no value. I am asking sailors who use the monitors how do they use them and how does the information change your sailing practices?

I installed a Link20 and thought at first how useful it would be. I loved that I could literally see how many amps any device would draw by turning it on and viewing the change in AMP display. I liked the precision compared with my oem Bosch gauges. I felt I had a better understanding of the state of things at any given moment. I like I can see how any amps the alt is actually putting out or the solar panels or the instruments... I tried to get the rest of the features to work for me... hours and % of charge and so on. Found them confounding and useless.

 

..... I am asking sailors who use the monitors how do they use them and how does the information change your sailing practices?.......

My primary interest is to be able to exactly monitor how much charge is being accepted by the batteries, so I can tell if my lead acid batteries are truly getting to full. It's both to maximize capacity, as well as longevity. Many/most chargers just flip over to float, after a programmed period of time, which is never correct.

I suspect capacity is often accommodated, by some sailors, with brute force. They add whatever inefficient capacity they need, until it works for them.

I also suspect many get confounded (and I was totally there too), because half the garbage out there isn't really doing what it seems to be claiming. For example, an amp hour counter that tries to tell you percent SOC is very unlikley to be right. You have to tell it total capacity, so it knows the denominator. However, this begins to degrade the day after you buy the batteries. Further, we all know capacity is based on the straight line 20 hr test. If you're drawing more than that number of amps, you have less capacity than the programmed denomitor and more, if you draw less. Some program this Peukert ratio, others don't. Who actually knows the right peukert for their battery anyway.

Next round, I'm moving on to lithium, which doesn't care if you get it back to 100% SOC frequently and the game will change quite a bit.

 

Yes, if the bank is expensive and longevity a priority,

time higher consumption loads for after it gets to Full, at least a few days a week.

Do motoring or run genny in the AM when I see solar won't be enough to get there by itself.

Stop drawing, or start up genny, when SoC gets below 50%

 

Yes, if the bank is expensive and longevity a priority,

time higher consumption loads for after it gets to Full, at least a few days a week.

Do motoring or run genny in the AM when I see solar won't be enough to get there by itself.

Stop drawing, or start up genny, when SoC gets below 50%

Are you saying that cycling a battery shortens its service life? Or only when it discharges x%? While this is probably true is there any information on the number of cycles we can expect from a battery?

I replaced my house bank in Spring 2012 w/ 2 AGM 8Ds so they about to start their 8th year of use. I had expected them to "die" this year but they seem to be OK so far... we'll see when I start seriously using the boat in the Spring. I do not use a 110v battery charge and rely on 110 watts of solar. We are on a mooring and when we are on board we will typically run the engine with a high output alt with a smart regulator for about 2 hrs each day. So far so good... and we never deeply discharge the batts. But.... I am expecting one day they will be finished... capacity gone.