People come to look at my project and one of the first things they notice is that the battery is in the back. I tell em thats not the battery, its BALLAST! Secondarily, it happens to provide power to the plane, but its main objective is to overcome the weight of the big engine and prop. Here are some shots of an access panel in the skin and the hold downs. Pretty simple rig. There is 1" high density foam under the 35A battery with a 2ga wire headin for the firewall. Right behind the battery is another ballast item, the ELT. And right in front of the battery is another ballast item, my smoke pump not in these pictures.