Powering high voltage (7.4v) servos on mRo Pixracer Pro

Hardware Pixhawk family
1

I am looking at my options for powering high voltage servos while using a Pixracer Pro

Servos are Align DS820M High Voltage that have an operating range of 7.4v-8.4v

I am currently powering the autopilot with a 5v power module through the designated power port.
The ESC I am using has a programable BEC. Is the solution to just simply program the BEC to 7.4v and plugging that into the servo rail to power the servos or will that overload the entire autopilot by providing 7.4v to the entire board?

Thanks for the help in advance!

2

The servo rail on those Flight Controllers are isolated. Connect what you want.

1 Like
3

Thank you so much for your reply!
I am quite new to the Ardupilot stuff as this is only my second build. Is there a way I can identify an isolated servo rail in the future? I tried my best to look over the documentation on the mRo website.

4

It’s a good question. I have a few PixRacers although they are not Pro’s. These Flight Controller have always had an output bus isolated from the board unlike a Pixhawk or others which can supply power thru the bus. I think it’s just a common bus for Power and Gnd. I don’t know what the max voltage spec is for this bus (Mro documentation is light) but I don’t think there will be any problem with an HV servo.

5

Every time I learn something new in this hobby, it makes me realize how much I still don’t know. I truly appreciate the help and quick replies.

6

The docs at mRo Pixracer Pro – mRobotics are not at all explicit about the servo power rail not actually being powered by the board. The main clue is that they don’t have any claims about an onboard BEC or regulator for the power rail on the servo outputs.

For comparison, the Matek H743 wing v2 (http://www.mateksys.com/wp-content/uploads/2021/09/H743-WING-V2_layout.jpg) specifically talks about “Vx” for powering the servos via an onboard regulator.

7

That was a wonderful example! Thank you for providing the info. It helped a ton especially since I used the H743 v2 on my first build. This community is awesome. Thanks for the help!