Where would it be a good place to install another battery? I thought of a smaller battery. About the size of a motorcycle or a tractor battery with at least 300 cramking amps. I thought that most of the time we only need a backup in case the regular battery cunks out when winching(playing the stereo for a long time). This would allow for the vehicle to be started and the battery charged again. I see very limited space inside the engine compartment. I agree we need the switch to go back and forth with the two batteries. Right now I have a jump start battery pack I carry in back of the truck.