[Si Coe]

It depends on your setup - but with modern electrics thats a bit drastic. You'll find with brushless and lipo you'd need something less than half that size. Typically we use about 1 to 1.5Ah per race, so you don't really need more than 11-20Ah from your leisure battery.

Actually most people just charge from their car. Unless you have several people hooked on or a knackered battery you'll not use enough to cause a problem starting the car.