Buying a battery that has been stored for more than 8 months

Nabiru3
Nabiru3 Registered Users Posts: 13 ✭✭
in Off Grid Solar & Battery Systems #1
Buying a battery that has been stored for more than 8 months, we all know of something called self-discharge and it happens inevitably with time. but what happens if the battery was stored for a long time and was discharged to less than 50% of its rated 20C capacity and the buyer didn't even bother to recharge the battery once awhile to let the battery stay above the threshold level ?  
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited July 2018 #2
    When a battery has been in storage for an extended period of time dropping capacity to levels as low as 50%, the battery should be fully charged then equalized, if flooded  to restore the capacity, using without doing so will eventually lead to permanent damage.Never equalize an AGM, unless the manufacturer specifies a boost charge.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited July 2018 #3
    You get some some permanent sulfation.   You could measure AH capacity and/or SG  to get an idea how much.

    I am available for custom hardware/firmware development

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,623 admin
    #4
    The battery is probably no good... 

    Trying to recharge it and test, perhaps you can get some use out of it...

    However, my experience with lead acid batteries that have been taken to dead (typical car battery), is that even if you get them working--They can fail a few days to weeks later (work OK for a bit, then the next time you use it, dead).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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