About to buy an AGM battery bank. Anything new or economical I should consider?

[Withalligators]

The best deal for quality I can find is 220AH 6V Crown AGMs for 227. 4 of those will put me right at 900. Any better ideas? Sprinter build, 981w of PV.
Cheers,
Alex

[monogram]

Check out Sam Club that has 6V 215A GC2 for $85

[littleharbor]

Check out Sam Club that has 6V 215A GC2 for $85

These are AGM batteries??

[monogram]

These are AGM batteries??

No, they are not.

What is the benefit for AGM when compare with GC?

https://www.samsclub.com/sams/duracell-golf-car-battery-group-size-gc2/prod3590228.ip

[Mike90250]

Generally, neophytes to solar, destroy their first bank of batteries. Better to fry a cheap learner set of flooded batteries ($400), than expen$ive AGM batteries. ($900)

[littleharbor]

No, they are not.

What is the benefit for AGM when compare with GC?

https://www.samsclub.com/sams/duracell-golf-car-battery-group-size-gc2/prod3590228.ip

If you look at the title of this thread you'll see the OP is looking, specifically, to buy a new set of "AGM" batteries. Your suggestion isn't AGM but FLA.

[Sunking]

No, they are not.

What is the benefit for AGM when compare with GC?

https://www.samsclub.com/sams/durace...prod3590228.ip

AGM is a high discharge and charge rate battery. Golf Cart batteries are both high discharge and high charge rate batteries and come in both AGM and FLA varieties. AGM cost more and do not last as long as FLA

GC aka Golf Cart is just a marketing name to indicate the battery is a HYBRID battery and is neither a Deep Cycle or Cranking battery. It is somewhere in between. That is why they call it a HYBRID. The Sam's battery is a low end DEKA GC battery.

[Withalligators]

Generally, neophytes to solar, destroy their first bank of batteries. Better to fry a cheap learner set of flooded batteries ($400), than expen$ive AGM batteries. ($900)

I can appreciate this. But they will be self contained inside a van. I'd like to avoid outgassing fumes, even though I hear they're not much of an issue, and vanagon guys have dealt with it forever. What steps can I do to maintain a 6 battery bank (3 parallel in 2 series) at 660AH? I've heard AGMs are pretty maintenance free. I'll definitely by charging them off the alternator while driving, and thinking about getting a balancer as well.

Cheers

[Mike90250]

.... maintain a 6 battery bank (3 parallel in 2 series) at 660AH? ....Cheers

Then you are already doomed. 3 AGM in parallel is tough to keep balanced

[Sunking]

I can appreciate this. But they will be self contained inside a van. I'd like to avoid outgassing fumes, even though I hear they're not much of an issue, and vanagon guys have dealt with it forever. What steps can I do to maintain a 6 battery bank (3 parallel in 2 series) at 660AH? I've heard AGMs are pretty maintenance free. I'll definitely by charging them off the alternator while driving, and thinking about getting a balancer as well.

Cheers

Never ever parallel batteries. Like Mike said you just signed your batteries death warrant. If you need 600 AH, buy 600 AH cells. They will not be 12 volt batteries. Either 4 or 6 volt batteries. A 12 volt 600 AH battery would weigh around 500 pounds. That is why you cannot find large 12 volt batteries over 200 AH.

FWI a 12 volt 600 AH battery needs 60 to 80 amps of charge current and that translates to 700 to 1000 watts of panels. Good luck finding a place to place all those panels.

Forget the Balancer, lead acid batteries self balance.

[Sunking]

The best deal for quality I can find is 220AH 6V Crown AGMs for 227. 4 of those will put me right at 900.

Incorrect. If wired for 12 volts (2S2P) is 440 AH.

[Withalligators]

Incorrect. If wired for 12 volts (2S2P) is 440 AH.

Sorry, I meant $900, not 900AH

[Withalligators]

Never ever parallel batteries. Like Mike said you just signed your batteries death warrant. If you need 600 AH, buy 600 AH cells. They will not be 12 volt batteries. Either 4 or 6 volt batteries. A 12 volt 600 AH battery would weigh around 500 pounds. That is why you cannot find large 12 volt batteries over 200 AH.

FWI a 12 volt 600 AH battery needs 60 to 80 amps of charge current and that translates to 700 to 1000 watts of panels. Good luck finding a place to place all those panels.

Forget the Balancer, lead acid batteries self balance.

I actually managed 981w of PV on the roof. so I should be ok there. I didn't know you couldn't parallel batteries. Damn. I actually came here to ask what you guys thought of 2 big lifeline 255AH 12v batteries over 4 Crown 220AH 6V batteries.

So, what do you recommend for ~500/600AH at 12V for an AGM battery bank?

[SunEagle]

I actually managed 981w of PV on the roof. so I should be ok there. I didn't know you couldn't parallel batteries. Damn. I actually came here to ask what you guys thought of 2 big lifeline 255AH 12v batteries over 4 Crown 220AH 6V batteries.

So, what do you recommend for ~500/600AH at 12V for an AGM battery bank?

It is not that you "can't" parallel wire batteries, the problem is that the chances of killing one or more off way before their true life increases which each parallel string.

I actually built a battery system with 4 x 12V 50Ah AGM type batteries all wired in parallel. They have lasted a couple of years but then again I rarely use them. If I did use them daily I would have probably replaced them with 2 x 6V 232Ah FLA type and would have spent less money and gotten a better battery system. Usually the first set of batteries are used as a learning curve and will not perform as expected.

Building an AGM battery system with a high AH rating may be difficult since the selection of high AH low voltage (4V or 6V) cells is not very big or probably cheap.

[sdold]

Some other engineers here recently installed several new AGM batteries at a solar site. They tried hard to make the wiring to all batteries equal. For fun I went up and measured the charge currents to each battery on a sunny day. The currents were (rounded to the nearest quarter-amp) 6.5 A, 6A, 8A, 6A, 4A, 8A, 3A, 8A, 5A, 8A, 8A, and 7A. These are all new batteries wired in a way that they thought would make the currents equal. It showed me first hand why parallel cycled batteries is a bad idea.