I am working on a boat and want too add a second battery too it that will be charged with the normal charging system along with the original battery but when I use it I do not want this battery to be able too drain the other battery. The add on battery is for a radio and occasionally a trolling motor. I was told there was some sort of kit too buy too do this but it is expensive(i think) so I was wanting too know if any of you have any ideas on how too do this. Maybe using a diode?
