Battery Charging from Another Battery

Discussion in 'The Projects Forum' started by RodneyB, Feb 9, 2013.

  1. RodneyB

    Thread Starter Well-Known Member

    Apr 28, 2012
    I have a 12 Volt 7Ah battery in my electric gate motor. I Am charging a 30Ah Battery with a 55 Watt Solar panel.

    At night 2 x 600mm LED tube lights are switched on through a 12 Volt day night switch

    I want the battery in the gate motor to charge from the solar panel but not feed the lights at night.

    Currently I have the batteries connected in Parallel.

    If I was to put a suitable diode on the positive going to the 7ah Battery wouldyhe 7 Ah battery still charge from the solar panels and feed fromthe 30Ah Battery but not provide power to the lighting circuit?

    Many thanks

  2. crutschow


    Mar 14, 2008
    A diode will provide isolation, but the minimum forward drop would be about 0.4V if you used a Schottky diode, which would prevent proper charging of the battery with the diode. Thus you need one in series with each battery to balance the voltage. This will reduce your charging efficiency slightly (perhaps 5%).