I normally would use a battery from a broken cordless drill for my breakaway battery. Last summer I planned to use the battery I saved from the van that was just not strong enough anymore to start it at the -20F temps that were commonplace. Well it didn't fit right between the rails, it kept falling through and we were packed and just about ready to go to the campground. The drill battery wasn't charged. So I made this up from a piece of appliance sheetmetal I had laying around. Cut it out with tin snips, pressbroke it on the corner of my porch, and drilled holes to bolt it in place. Did it in about 20 minutes and we were off. I am painting it right now along with the rest of the frame.