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Small Cabin Forum / Off-Grid Living / Battery Bank ?
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customrunner
Member
# Posted: 11 Jul 2012 13:20
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Well here is my Question, Can I have to many batteries on my system (as I have been given 20 6v batteries that are only 4 mounths old)I have 4 95w panels (will be adding one more 95W panel and a 500W wind gen)and on my system I have 8-4w lites, 1-19" lcd tv, small electric fridge and a 12volt water pump any input would be great.
Thanks Chad

Dillio187
Member
# Posted: 11 Jul 2012 13:42 - Edited by: Dillio187
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yes. the batteries you have sound like 6V golf cart batteries (they will say GC or GC2 on them) at 220ish ah each. They could also be some sort of renewable energy battery made by Trojan etc.

You will have 475W of solar charging capacity, and 500W wind (when blowing)

at 12V after efficiency losses, your solar array will probably charge around 30 or 35amps best case. The wind generator will be a crap shoot from what I've seen.

Those GC batteries like to be charged around 10% of their ah capacity, if you go much less, they can sulfate and be ruined quickly. This happens because when charging at a good rate, they will actually bubble and break the sulfate off the lead plates.

With that setup, I would recommend using 4 of the batteries in a series/parallel setup. 2 batteries in series to make 12V, then 2 parallel strings to make a ~440ah bank. More solar panels would work fine with 4 batteries as well to get the rate up closer to 10%.

if you want to use more of them, then you're most likely talking about upgrading to a 24V bank, more panels etc.

good luck

241comp
Member
# Posted: 13 Jul 2012 10:58 - Edited by: 241comp
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You definitely don't want to exceed 3 battery banks in parallel (maybe 4 at the very most with brand-new, high quality batteries). Manufacturing variances will begin to cause contention if you exceed 3 parallel banks and you will find you experience phantom drain and/or continual overcharging/undercharging that will destroy your batteries. So, to utilize 20 6v batteries, I would highly recommend going to a 48V battery bank. Save 4 batteries as extras to replace batteries when they go bad, running 2 parallel banks of 8 batteries or purchase 4 more batteries and run 3 parallel banks of 8 batteries each. Definitely don't exceed 3 parallel banks with used batteries.

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