In our Winnebago class C the house batteries are under the entry step. I got rid of the two group 24's and bought two 6v golf cart batteries, which are sitting on the floor in the garage. Yesterday I was looking at the battery cables in the battery box and when I moved the positive cable it touched the side of the steel box. There was a spark. Obviously, I think, the source of the current has to be the engine battery but how? Where do these circuits share a common point? Do I have a problem?