Possibly an in-line automotive fuse, the common modern blade type fuse, on one of the battery leads would be easier to install and use than a switch, and weight would be less than a switch. Just be sure to install one with a fuse that is of adequate size to handle the amps your power system will be requiring of the battery. I have never utilized this concept, but it seems better than some alternative approaches and it is simple. Good luck - - -