12v 100ah batteries over discharged


  • I have 2 12v 100ah  batteries (one with Bluetooth and one without) connected in parallel connected to solar panels using the Renogy wanderer charge controller and also a Renogy dc-dc charger from the van starter battery.

    The batteries drained to 0% and the solar charge controller says the batteries were over discharged. I have used a voltmeter and both batteries read 11.85v. The batteries recharged to 65% according to the solar charge controller and then after driving for a couple of hours the batteries were back down to 34%. I have disconnected it from the circuit so no electricity is being drawn and the batteries are staying at 34%. I have the engine running so it should be charging but it doesn't seem to be doing anything. Is there something I need to do for the batteries to charge properly again? 



  • Don't know if you figured this out yet but I would suggest checking the DC-DC charger setup and polarity.  Also, make sure your charge controller is set properly and has enough amperage to charge the batteries AND supply the electricity that is being used at the same time.  I use a 40amp MPPT from Rich solar for my travel trailer and have 800watts from solar only.  I do not charge from the truck battery as it seems to be too hard on the alternator.  I run the trailer with two 12v100ah Vatrer batteries with no issues.  Even in the winter with the furnace running.  The inverter is a harbor freight pure sign wave 3k.  It does a great job.


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