Motorcycle battery won't work, neither will typical car batteries, you need a deep cycle battery. A golf cart battery is such a battery. They also have deep cycle gel-cell batteries too, these are sealed and can be mounted in any angle. Much safer and more flexible.
I remember seeing these back in the 70s. Not very fast though.
You're right about it not being fast, but it will pull you up a hill (if you manage to get to the top before it eats the tire)