Charging a battery is not like re filling the tank.
I'd beg to differ. Charging the battery and re-filling the tank both do the same thing, they replenish the power source.
You don't have to kill the engine to re fill the tank.
You are 100% correct. Electric don't use engines. Also, whats the big deal of turning the power off? Starting an electric is one million times easier then starting a nitro.