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Battery bank drops drastically to 12.4 volts!!!

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  • #16
    The manual recommends:
    0 - 1.5m = 6mm square
    1.5 - 3m = 10mm square
    My cables from inverter to batteries are 4 ft (1.2m), I've used 10mm square cables.


    • #17
      The cable size appears to be fine as long as you aren't going above 500W. 8 AWG wire is rated for 50A (@75C conductor cable rating) and the inverter produces 41.6A at 500W.

      Do you have any fuses or breakers on your system to protect the wiring? If not that's maybe a safety consideration you should consider.

      Have a read of this article -

      In general, charging inputs raise the actual voltage on the battery above its resting voltage, and loads (drains on the battery) lower it below its resting voltage.
      You need to determine what the resting voltage is of the batteries when there is no loads whatsoever - just turn off the inverter and charge controller and wait a few hours (maybe 4) after a good sunny day charging. Use a multimeter to measure the voltage (not the charge controller). In those 4 hours just treat things like a power cut since you are using this system for 100% of power (use your backup torches and lamps). It's better to find out as soon as possible if there is a problem otherwise you could lose your investment in the batteries.

      I'm not an expert at all, but that will probably give us a much better idea of whether the battery is fully charged or not.
      Last edited by DavidH; 09-22-2019, 11:23 AM.


      • #18
        Thanks DavidH for the helpful info.

        No my load is not near 500W ( may be when the TV is switching on the lights flicker, its an old LG, CRT type so I guess its the power surge)
        I have a 15 amp breaker btwn panels and CC, and a 30amp breaker btwn CC and batteries, no fuse or breaker btwn inverter and batteries.

        I will determine the resting voltage of the batteries ASAP.