I want to charge a 12v battery because the 12v outlets shut off when the screen is off and therefore the appliance won't run all day. The voltage of the outlets are 13.6. how can I protect the Telsa electric system. I think a 10amp fuse and a cut out relay are not enough. Can I use a solar controller. The refridge draws 2.5a and I plan to get at least a 30 amp hour auxiliary battery.