Specific gravity, acid strength

adas
adas Solar Expert Posts: 136 ✭✭✭✭✭
in Advanced Solar Electric Technical Forum #1
Aloha, I got a large 24v 810AH forklift battery that has one cell around 1.7 volts and the rest are up around 2.10V. I tasted the water in the cell and it was almost like water....no acid and the other cells have definitely have acid. What is the method to equalize the acid content of each cell?
If I check specific gravity, will this indicate acid strength or just state of charge?
I have a PH meter, should I use that? and if so what should the reading be?

I have the batteries hooked up to my panels for 2 days now and the FX80 has been on float.

thanks,
Frank
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Comments

  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: Specific gravity, acid strength

    It sounds like you have a dead cell. (BTW "tasting" the acid is not consider a good or SAFE test!)

    You MAY be able to save it if you do an equalization charge. ( A deliberate over charge of the battery under controlled conditions) See the following:http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq4.htm#charge or this, http://www.batteryfaq.org/ or even this :http://www.batteryfaq.org/

    The are almost required reading for any PV system.


    Tony

    PS Adding acid to the dead cell will not save it and is not generally recommended.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #3
    Re: Specific gravity, acid strength

    it sounds like that cell may be partially shorted. definitely try to eq it, but anytime there's a variation this bad then the battery may not be long for this world as it may be just a matter of time for the other cells to do this too or for that cell to totally fail.
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  • adas
    adas Solar Expert Posts: 136 ✭✭✭✭✭
    #4
    Re: Specific gravity, acid strength

    Aloha, yah, I am going to try to eq it, but it has been cloudy the last couple of days.

    Any recomendation for Eq voltage levels and times?

    If no worky, I will change the cell out. Making the tools now to do it, (and am familiar with hydrogen explosions). :cry:
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: Specific gravity, acid strength

    Either follow the mfg's recommendations (if available) or follow the battery FAQ.

    More of an issue of the amount of current (and time) going into the battery than absolute voltage. You need the right current going through all of the cells--a shorted, dead, overcharged, or open cell will all affect the observed voltage... An open cell will affect the desired EQ current.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: Specific gravity, acid strength

    well i never have eqed a battery in my life and your battery is a general generic run of the mill so you can check out this from xantrex,
    http://www.xantrex.com/web/id/257/DocServe.aspx
    what xantrex lists seems high and harsh to me. now you could go by what outback has the mx60 set for (http://www.outbackpower.com/pdfs/manuals/mx60_pv_mppt.pdf see page 34. they say 1 hour and you can try 2 hours as it is far enough out to warrant that.
    it doesn't matter if it is low after you tried eqing from the mx60 defaults because you can eq it again with longer times and/or up the voltage somewhat. slower is better sometimes as it can avoid possible damage or overcooking the battery. after each eq allow for at least 2-3 hours of rest to observe the voltage of the cells and watch your electrolyte levels.
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