Electronic speed controls (ESC) are used to throttle an electric RC motor. ESCs do not work like variable resistors that change the amount of current running to the motor. ESCs always supply full current to the motor but do so in pulses. The more frequently the current is on, the faster the motor turns; reduce the frequency and you slow the motor down. Many ESCs contain a battery elimination circuit (BEC) that allows the modeler to use the same battery to power the motor and the servos. This BEC eliminates the need for a separate, on-board battery pack for the receiver and servos and reduces the model's overall weight.
Plug the "Y" cable into channel three on the receiver. Channel three is the throttle channel.
Plug each ESC into a leg of the "Y" cable. Connect each motor to the ESC that will control it. If each motor will be powered by its own battery, then you must disable the BEC function on one of the speed controllers. Check the speed controller owner manual for instructions on how to change this setting.
Install a standalone BEC device if your speed controllers do not have the feature. This is common on speed controllers that handle higher-amperage applications. The standalone BEC allows you to use one battery to power a motor and the receiver and servos; the other battery will be dedicated to the second motor.