In electric flight setups, you never plug the main flight battery directly into the receiver. In a typical small electric plane, you plug the battery into the electronic speed controller (ESC), then plug the ESC into the throttle channel of the receiver. The ESC contains a battery eliminator circuit (BEC) that regulates the battery voltage down to a level that is safe for the receiver. The 3-wire cable connecting the ESC to the receiver carries the regulated voltage to the receiver in its center conductor.

In some larger electric planes, you might use a separate battery of the appropriate voltage (4.8-6.0V) just for the receiver and servos. In such a plane, you would disable the BEC in the ESC. The disadvantage of this arrangement is that the plane must carry the weight of two battery packs. It is usually not practical for small planes.

A third possibility is to use just one main battery but connect it to both the ESC and to a separate standalone BEC. This arrangement is used where you want to use only one battery but the BEC built into the ESC can not handle the current required by the receiver and servos. You disable the BEC in the ESC and let the standalone BEC provide power for the receiver and servos. The standalone BEC is lighter than a second battery pack.

- Jeff