battery replacement question

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martinf
martinf Registered Users Posts: 5 ✭
in Off Grid Solar & Battery Systems #1
Im working on a friends system, solar with a gen backup. he has one bad battery (failed a load test) and wants to replace just that one. I know that's a no-no, but what would you folks do in this situation? The batteries are six volt spendy Rolls 350amp/hour, 2 banks of four each. Fairly old...eight years? And the catch is that grid power is coming to his area in a year or so, so hes not into buying all new batteries, and yet needs things up and running til then.

Should I install a new Rolls, four hundred bucks, knowing that the other older batteries wil shorten this new one, or should I install a somewhat used Trojan smller 250 amp/hour that I can get for 100 bucks? Is it ok to install a smaller battery in a bank of bigger amp/hour batteries? Given that this project is to just keep him going for a year or so....

Thanks for any assistance
Martin
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: battery replacement question

    Welcome to the forum Martin.

    If it's a case of making the system last for just one more year then look into getting a cheaper battery of similar capacity just to replace that one. Crown batteries are usually less expensive and they have a 6 Volt 330 Amp hours CR-330 which should be <$300.

    Of course an eight year old bank is likely to fail 1-2-3 so don't be surprised if another one gives up in a month or so.

    Which leads us to re-evaluating the capacity need. Could he drop one string and use the generator more? Or put in a new string or two of smaller, cheaper batteries like GC2's @ 220 Amp hours? You can sometimes get them from a warehouse store for <$100 each.

    And if the grid does not arrive on time then he'd need a new plan of action.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #3
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    Re: battery replacement question

    There is no win in this situation, based on all the information I'd go to Sams and buy 2, GC-2 's and parallel them in the string and let it ride. $170. The Trojan will work also, $100 sounds cheap for one.
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