Updated: Jul 3, 2020
ESC is abbreviated as electronic speed controller. The function of an ESC is to take in signal from the receiver(as per the transmitted signal from transmitter) and convert these signals in terms of 3 phase AC. source and supply it to the motor.
ESC's come in different ratings like 5A, 10A, 30A and so on...
What are these ampere ratings??
For example if the ESC is rated as 20A, then at the max a load(motor in this case) that consumes around 12 to 16A can be plugged to the ESC. The current consumed by the motor will be given in the datasheet of the motor by the manufacturer. Any ESC with about 5 -8A greater rating than the current drawn by the motor can be used.
Number of cells and BEC output ratings:
(note:some esc's do not have inbuilt bec)
ESC's will have the input voltage limit printed in terms of number of lipo cells.
For example if it shows 2-4s then the maximum input voltage is around 16.8v(4s). voltage applied more than that can cause permanent damage to the ESC.
BEC ratings: BEC stands for battery eliminating circuit. The function of BEC is to take up the voltage from the battery and reduce it to 5V(in general) with 2A output which is then fed to power the receiver, servo motors and any other electronic sources in the model.
Wires from an ESC:
ESC will have one set of wires to connect to the main battery source(usually red and black).
Another set of wires to plug into the motor(3 set of wires).
And one more set of wire with a tiny connector which is plugged to the reciever.
Usually it will have a black, red and white colored wire. The black and red wire is the output from the BEC and powers the receiver and servos. The white wire including the ground(black) is the signal input to the ESC.