A receiver can have its own battery but that is usually for gas powered planes. The receiver usually takes 4.8 volts for power. However on electric planes the ESC (electronic speed control) does all the work for you. The ESC is the key to the entire electrical system. The battery connects to it at full voltage (7.2v for your 6 cell), then the ESC sends 4.8v to the receiver through a wired connection and it also sends full voltage (7.2v in your case) to the motor . It modulates the voltage to the signal it receives from the transmitter making the speed of the motor fast or slow.