To fly lighter, faster and cheaper! First, what are radio control BEC models? BEC is the abbreviation for Battery Elimination Circuit. It indicates that the battery that powers the motor is also used to power the receiver, the servos, and the throttle! In the early days of electric flight, we used a separate battery for the motor and another for everything else. So by having a BEC, we are able to eliminate up to 50% or more of the total battery weight!
The BEC is part of the Electronic Speed Control circuit board which controls the throttle function of the motor in radio control bec models. The ESC is plugged into the throttle input on the receiver with a 3-connector plug that looks just like the 3-wire connectors which attach the servos to the receiver. Usually on the same end of the ESC will be two heavy wires, typically red and black, to connect to the battery. These must ALWAYS be connected to the similarly colored wires battery wires to maintain polarity. The use of a polarized plug, like a Dean’s or Anderson Power Pole is an inexpensive way to avoid reversing polarity which will likely ruin the ESC!
From the other side of the ESC will be either two heavy wires for brushed motors or three wires for brushless motors. With the radio control BEC models’ motor wires (NOT the battery wires), if you need to reverse direction of rotation, just reverse the two wires for the brushed motor or ANY two of the three wires for brushless motors. Always carefully follow the manufacturer’s directions for attaching the ESC to avoid damaging the unit.
One other characteristic of the BEC is that there is a limit to the number of servos that can be powered by a battery elimination circuit. This will be detained in the instructions for the ESC but typically is 3 or 4 servos, depending of the amount of current they each draw. For all but the most sophisticated (read expensive) models, this will be adequate to operate rudder, elevator and ailerons. In many ESC’s, you can program a BEC shutoff, so that you could use a separate battery if you absolutely had to have more servos than the BEC could handle. Just refer to the instructions to learn how to make this setting.