The big problem you have here is that your charging system is only designed to charge one battery and if you ask it to charge 2 batteries, you are going to start ruining alternators. The best way to do it is the way they do it with boats, by using a central switch that can be switched to Bat1, bat2, both or none so you can control when they are connected and then only charge one at a time.
Sep 6, 2012 at 12:16 AM