OPTO-Isolation and BEC Power

Are KDE Direct ESCs opto-isolated?
Yes, all KDE Direct ESCs are opto-isolated. This means that the power to the ESC via the control lead (white, red, black) is isolated from the battery leads and the signal is transferred via light (photocoupler). We recommend connecting a 5V UBEC to the ESCs if your flight controller does not supply this voltage. Some flight controllers provide this power to the ESCs while others do not. For example, if you are using a Pixhawk we recommend connecting a 5V UBEC to the MAIN output rail. While we recommend using a UBEC, any regulated DC voltage will work.

What is a UBEC?
The purpose of a UBEC is to regulate the battery voltage down to a lower voltage to supply power for other electronics (ESCs, servos, gimbals, etc.) without the need for an additional battery. There are two types of BECs, linear and switching. Linear BECs burn off excess voltage through resistors as heat. Switching BECs (UBECs) produce voltage that does not waste power through heat. There are two types of UBECs that we offer: The UBEC-UVC (14S max) and the UBEC22 (8S max). Please note that you cannot use a UBEC in parallel or series with another UBEC.

Why do I need to supply additional voltage to the ESCs?
While KDE Direct ESCs will function without 3V – 12V, if this voltage isn't provided then the signal received by the ESC is not fully on. This additional voltage amplifies the signal the ESC receives. You can see this happening if you run a motor and remove the red control lead wire, the motor output decreases. The additional voltage also reduces electromagnetic and RF interference. If the voltage isn't provided then the throttle calibration endpoints will also need to be adjusted to compensate. The ESC will draw less than 60mA through the red control lead wire. The opto-circuitry is rated up to 35V max.