Battery Short?

Seanadirondacks Registered Users Posts: 20 ✭✭
In a battery bank of 4 -12 volt yellow tops strung in parallel. If 3 read 13.7 while charging but one reads 12.5. Should that battery be removed from the bank due to short? Thanks.


  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭

    Hello Sean ..,

    Just my opinion,   but,  if you have four batteries in PARALLEL,   and you are getting a significantly different reading when using your DMM to measure between the two TERMINALS on one battery,  then there is a very poor connection somewhere.  Make sure that you are measuring the battery terminals.

    This type of situation is one of the reasons,   that parallel battery strings are so problematic for almost all who try to use them.

    Clean all battery terminals,   and lugs on the battery cables,   carefully.  Measure the voltage of each battery,  when interconnects are not connected.   Use petroleum jelly on all of these contact surfaces,   and reassemble.

    IMO,   Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    In addition to Vic's advice, which is certainly appropriate, I would remove the low battery, try charging it on its own, and keep an eye on battery temp while doing so.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited April 2018 #4
    @Seanadirondacks if using batteries in parallel, please read the information in the link, it will answer many questions you may  have not thought about yet. Effects on Batteries
    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.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.