best batteries for a battery bank 400 amp

[nyrussell]

For energy storage?

 

[GJH]

400 amps at how many volts? (See "Battery Math" thread). Gotta know that first. Or put another way, how many kilowatt hours?

If you have the height, I like L16's: 2 for 12 volt or 4 for 24.

 

[Pete]

I went with Lifeline AGM batteries and think they are great. Absolutely no maintenance, more watts per pound than anything else I know about, accepts a much faster charge than wet cell or gel, almost zero self discharge when not in use, have the same charging voltage requirements as a wet cell (no new regulators), have the lowest internal resistance giving less voltage drop under heavy loads, no acid fumes, and can operate on their side if you want. I even installed a removable shelf above the battery bank for storage, that can be removed with six machine screws. The one negative is price. But no maintenance was worth it to me.

Pete

 

[GJH]

Just out of curiosity Pete, how many kilowatt hours have you pulled out of those Lifelines, and how are they doing now? As a means of comparison, I have pulled 34,700 amp hours out of my 4 US Battery 400AH L16s in one year of use. That's about 833 Kwh (24 volt system). At that rate, they may have another year to go, perhaps less. They were $190 apiece. If I don't go ahead and put in the small second generator I dream of, I will likely double my inverter bank size. I lean towards going for the Rolls; watering is very easy to do on my boat. However, there is some attraction to the AGM if they will last longer, though I note the Lifelines just go to 300AH, which I guess is offset by the ability to draw them down further.

Anyway, I'd love to hear yours and others' experiences.

 

[REBrueckner]

Noel,

By posing your question in amp hours you imply this bank will be used for deep cycle purposes.....in other words, low amp draw with many hours use...like a refrigeration system for example....For that type application AGM gives the lowest life cycle cost per amp hour delivered...(it's most economical overall) but the first cost is relatively high.

Pete's post captures most AGM advantages. In addition, for frequent charging via genny, not only do AGM's accept charge about three to four times faster than wet cell lead acid batts, if you have the charging capacity, their low internal resistance means EFFICIENT charging...about 15% or 20% less power is required due to low,low heat generation....but that speed and efficiency don't mean much if you only charge via genny a few times annually. Shore power is cheaper than buying expensive AGM's; genny based power makes AGM's VERY attractive unless you are running your genny anyway, say for air conditioning....Contrary is popular belief, I believe manufacturer specs show very deep discharges for AGM also reduces lifetime power delivery...but check whatever brand you choose.

For engine starting purposes, the usual criteria is CA or CCA...maximum cranking amps at cold temperatures....AGM's are fine for that, but the high cost makes them a less obvious choice...traditional wet cell lead acid for starting is just fine...A typical start uses less than 1% the amp hour capacity of starting batts...But paralleling AGM and wet cell except for short period starts is not a great idea....and maybe you don't want to mix battery types aboard,,

Also, you should ideally have a smart charger for AGM's as to be able to select "AGM" battery type...

My mechanic just told me he has been installing AGM's and owners have had excellent experience charging them with older style ferroresonant (non smart) chargers....I believe the maximum voltage difference is only 0.1 or maybe 0.2 and he has said the AGM's do just fine because the voltage difference is so small...
however, the time and shape of charging, that is the charge characteristic, betwen AGM and wet cell may be different and for deep cycle applications that might shorten battery life. I doubt my mechanic knows how owners actually use, deplete the batteries...for starting or actually for deep cycle use...so I takle that input with some doubt.

 

[Pete]

George, although the instrumentation is there, I do not keep track of the details you mention. I do not anchor out. I suspect if I did, this would be much more interesting to me.

The top two priorities when I replaced the batteries were, first, no maintenance and second, minimum internal resistance. The previous batteries were Rolls 8D's with Hydrocaps. My experience was less than pleasing. With a Trace Inverter/Charger set to the exact voltage levels suggested by Rolls, the batteries had to be watered every three months. The fact that the batteries sat behind the starboard engine in the engine room probably contributed to the watering requirement (heat). The Hydrocap did allow vapors to escape into the enclosed Todd battery boxes so there was ongoing acid clean up task to get the small amount of liquid that condensed and dropped to the bottom of the box and under the batteries. The Hydrocaps were delicate and prone to breaking at their base. The Hydrocaps had a bayonet mount into a base that appeared to snap into the battery access ports. This black material reacted with the battery acid and became soft, making turning the Hydrocaps difficult and as a result, broken Hydrocaps. Add to all of this a constant acid film on the batteries due to acid vapor, and I knew my next batteries were going to be true maintenance free. Between Gel and AGM, the lowest internal resistance requirement, made AGM the clear winner. AGM's also offered the bonus of charge voltages compatability with wet cells. Why lowest internal resistance? To drive a Sidepower 24 volt 400 amp bow thruster.

My setup has 4 Lifeline 8D's that handle all the DC requirements on the boat except the starting of the port engine and the generator. The port engine has a single Lifeline 8D that only starts that engine. The generator has a dedicated series 31 Lifeline for starting. The DC bank has a automatic series/parallel switch (a Sidepower product) that provides 24 volts during bow thruster operation. The bank of 4 batteries are charged by the Trace Inverter/Charger set to 125 amps, its max output. The port engine and generator batteries share a separate 3 stage, 2 output, charger

All the batteries are close to 4 years old and act same as new. About six months ago I decided to open up all the battery boxes and check the connections for sufficient torque. Everything looked like new.

Pete

 

[GJH]

Thanks Pete for the detailed response. In my case all 15 of the batteries on board are very easy to water, using one of those special pitchers from NAPA. I'll have to do a cost/benefit analysis when the time comes; your post will be helpful. It's always nice to have some real world feedback.

My array is as follows:
2 NAPA Commercial 8ds for the 24 volt bow thruster and Furuno NavNet electronics, charged by a Xantrex XC 2524.
One NAPA Commercial Group 27 (sealed, but not AGM) for the generator starter and a few very low or seldom drawn on accessories, charged by a ProMariner Sport6.
4 US Battery L16s for the 400 ah 24 volt inverter bank, charged by the Magnum 4024 Inverter.
All of the preceding are in the generator room.
Then 4 Interstate 8 volts for each engine, one also acting as a house bank, charged by a Sentry 30 amp ferro-resonant. All in all, a pretty big garden to water!

Ferro-resonant chargers can work on AGMs if they are the type (like a Sentry), that shut off completely, rather than apply a trickle charge. A smart charger is a better choice. I have the chargers for all the banks I might consider changing, so that expense is covered.