Originally Posted by Flybob
Disconnecting either battery terminal insures no battery drain other than internal leakage. The only problem is that you have to remember to reconnect battery prior to towing or you have no break-away brakes.
BTW, There could be some very small leakage if the top of the battery is a mess. Water, dirt, and who knows what on the top of the battery between the terminals could actually conduct a small drain. Highly rare and only in extreme cases of major build-up of 'stuff' on the top of the battery, but something to think about.