Old string/new string

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oglethorp
oglethorp Solar Expert Posts: 30 ✭✭
in Off Grid Solar & Battery Systems #1
If,:, with adding a new string of 8/6v golf cart batts, to an old string of 8 it can lessen the life of the new one as they team up,, my question is,
When charging will they even out when equalizing. I would think that as they discharge the old one will drag the new one down to its level??
How best to get the best out of this awkward situation without buying a new string to match . I also have a batt switch that allows me to just use one string at a time.
Hope this question makes some sense as I seem to have a very steep learning curve.
Thanx very much for you answer guys out there,
Phil in central Maine
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  • Photowhit
    Photowhit Solar Expert Posts: 6,003 ✭✭✭✭✭
    #2
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    Re: Old string/new string

    How old are the batteries? if they are under a year and you absolutly need the capacity, I'd just go with it, If more than a year, you might talk with a local golf courses, perhaps they would let you pick over their replaced batteries before they get sent in for exchange(though this typically happens in the spring), I use to do this at Sam's club, but they must have some OSHA warning about 3 years ago.

    When I brouched the subject with AL Simpler of Simpler Solar systems 15 years ago (he had already been in the business 15+ years) he said if I must, be sure to do an equalizing charge just before adding the new string. As it turned out I choose to abuse the batteries I had, drawing them down lower than normal, and by fall my living arrangments had changed and I was glad I hadn't bought a new string.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #3
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    Re: Old string/new string

    If the "old" string is more than a year old you might try this. Install a 1/2/1+2 battery switch and use them together (to get the advantages of the Peukert effect, which basically gets you more amps from them together than using them as 2 separate strings). Then charge them as separate strings so they are topped off correctly.

    That will still shorten the life of the newer string somewhat but not as much as using them and charging them together.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • oglethorp
    oglethorp Solar Expert Posts: 30 ✭✭
    #4
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    Re: Old string/new string

    New string is 1 month old
    Old string of golf cart batts are "7" years old,, well seven of them . I lost 1 on that string last week. Added a used one from golf cart place.,
    Surprising as it is and I ve heard a lot about it,, but as I needed to add fluid to the old batts ,, I use Distilled White vinegar . Old timer Maine thing.
    I try not to let the batts get below 25% discharged and use a EU 2000 honda thru a Magnasine and let it run over night, uses 1 gal of gas when needed, Eq about once every month at 62v
    I hope to hear some comments about the vinegar
    Thanx,,
    Phil Central Maine
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #5
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    Re: Old string/new string

    i would not mix those old batteries with the new ones.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #6
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    Re: Old string/new string

    Never heard of using vinegar, I would imagine over time the volatiles would boil off before the water, leaving mostly water. But that initially after each refill the ph is raised quite a bit.

    I agree with niel, with a string that old I wouldn't even use them together as I suggested. It could completely go at any time, your best bet is to go out right now and buy another new string before your current new string gets too old, then you can use them together safely.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #7
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    Re: Old string/new string

    The SG of vinegar is only slightly above water (1.08 ). There would be no advantage to using it instead of distilled water.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #8
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    Re: Old string/new string

    But the pH is low, so you are adding acid on top of acid. Doesn't sound good to me.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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