As klaymon mentioned, the receiver and servo's require battery power to run your nitro car.

If you only have AA's, you can even use one of these brackets. Just make sure the black and red wires go into the receiver in the right polarity.

http://www.amazon.com/Futaba-FBB1-Ce...ver+battery+rc

For charging these smaller receiver packs, if Nicd/Nimh, I'd use a slow charger. Usually transmitter chargers have the
transmitter and receiver charger receptacles.