Servers by jDrones

UBEC help needed

Hey all,

I’m wiring up a octo X heavy lift build from the ground up and I am looking for advice on how exactly to use the built in UBEC’s in my Tmotor 80A ESC’s. My level of electrical knowledge is lackluster at best (Black go to black red go to red hur dur) My understanding is that the 3 wires coming out of the ESC are power ground and signal, in all my previous builds I’ve just plugged all 3 from the ESC into the flight controller and left it at that. However since my build has no step downs built into the PDB I was wondering if I could just plug in the signal wire from the ESC to the flight controller and run the power and ground from the ESC to my landing gear servos, LED’s and other accessories. Any help would be appreciated :slight_smile:

Good day, for the servos on the landing gear i suggest you to power it with an ubec…, if you have enough space of the frame just add s second battery for provide the power of alternatively you can add a second pdb with ubec 12v to 5v or 6v for the same scope.
what’s your fc?

My FC is a Pixhawk 2.1 with the cube: https://www.getfpv.com/hex-pixhawk-2-1-the-cube-orange-standard-set-ads-b.html?afid=aVlOV0hBdmd6THc9&gclid=Cj0KCQjw8IaGBhCHARIsAGIRRYrfNXViV3QAUKH6xEDwfiRPKNOPXg-h00Bo2WVVcCbmIHxKl7M1X0kaAo_BEALw_wcB

That’s a good idea to use a UBEC to power the landing gear servos, I’m curious if the UBEC’s built into my ESC’s will work as well as an external UBEC, my ESC’s are T-motor 80A units with built in UBEC: https://store-en.tmotor.com/goods.php?id=376

If all else fails I will go with a external UBEC but I’d like to know if the UBEC’s I have in my ESC’s will safely work for providing auxiliary power.

Personally i will not use the ubec in the esc for power the servos… just consider that servos work continously when powered but you can make a test and check with an oscilloscope if you have spikes during the use

The BECs of those particular ESCs are 3 amp switching regulators so they should be OK to power one or two servos each (depending on the servo’s power requirements).
@Dave84 likely has a good reason not to trust BECs on ESCs but I personally use these BECs in several of my quads and airplanes.
Some ESCs use linear regulators for the BEC. A linear regulator will heat up much more than a switching regulator. I wouldn’t use a linear BEC for a servo.
In general you don’t want to connect multiple BECs in parallel. Only one ESC’s power lead should connect to your flight controller. Parallel BECs don’t always blow up but this happens often enough that I think it’s a really bad idea to use them in parallel.
I personally divide up the 5V power requirements in my aircraft so the power is distributed amount the multiple BECs. In an airplane, I’ll use the BEC on the right wing motor’s ESC to power the right wing’s servo(s).
As @Dave84 suggests, you should check to make sure the BECs can handle the power requirements before putting the aircraft in the air. I doubt you have an oscilloscope based on your self described “lackluster” knowledge of electronics. Instead you can try other methods of testing the BECs such as cycling the servos multiple times and making sure they behave well. Make sure to feel the BEC circuit on the ESC to see how hot it gets. Some electronics can operate safely while being too hot to touch but in general, it’s a bad sign when electronics get really hot.

Servers by jDrones