Electrical – use a MPPT Solar Controller to charge the auxillary 12V AGM Battery from the car battery/alternator

alternatorbatteriesmpptsolar cellsolar-charge-controller

I have a RedArc solenoid and a Victron 75/15 Smart Solar Controller. Can I use the combination of these two units to charge an 12V AGM Deep Cycle auxiliary battery from the car battery/alternator when the car is running ?

The RedArc solenoid is no longer battery sensing and only works via the override lead being pulled to 12V. I'd connect this override lead to the car's ACC or running output of the vehicle.

Second, the Victron unit provides multi-stage charging and is configurable for multiple different batteries and provides some nice feedback via the Victron App.

Third, if this combination does not work, can I add a RCNUN BuckBooster ( Input 8-32V DC, Output 13.8V 8A – Constant Current output from 8-13.8V) between the solenoid and the MPPT Controller to regulate the output?

I have been pondering this for some time. I have the piece hence the interest. Thank you.

Best Answer

Your alternator is already set up to charge a battery. It won't put out more than 13 - 14 volts and i believe charge controllers are set up to run form much higher solar panel voltages at much lower currents. You could just (Jump) the AGM battery in parallel and the alternator would charge it along with your car battery. You may be over complicating this problem with the charge controller?