Hi, I an fitting a solar panel to the roof of my p38 range rover.I will also fit an auxillary battery to use while caravanning. The panel will charge both batteries, as they will be connected together. However I do not want the car battery to discharge whilst I am using the caravan, nor do I want the starter battery to draw current from the leisure battery when it starts the car. Does anyone have any ideas if this is possible or not and if so how could I achieve what I want ? Any help would be greatfully recieved yhanks in advance .