The Mystery of the Misbehaving Motors

Picture this: You’re excited to test your drone’s motors one by one, but instead of smooth, independent control, you encounter a strange behavior.

  • The first motor starts, but it seems to set off three motors at half power.
  • The second motor follows suit, triggering three motors simultaneously.
  • The third motor works as expected, engaging only itself.
  • And the fourth motor doesn’t respond at all.

But here’s the twist: when you turn on all the motors together, they miraculously come to life and function properly. What’s going on?

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Are you referring to the motor testing function in QGroundControl?

Almost sounds like a bridged connection somewhere in the ESC to me. Double check the ESC boards, especially all the pad soldered connections, some of those wire terminals are really close together and could accidentally touch if you’re not careful.

Additionally, did you get the kit last year or this year? At the start of last year’s season, there was a bad batch of ESCs that got recalled, that could possibly cause something like this.

Also, is it flyable? I’d assume not since it seems you’re still in the building/testing phase, but if they function properly together, it may be some sort of silent bug.

After weeks of trouble shooting we swapped out our flight controller for a new one. This fixed the issue.

We saw this with another team this past weekend. I took the FC home with me to test and I still the same problem. Motor 1 and 3 outputs appear to be bridged. This happened even after flashing firmware multiple times. At first I assumed it was an ESC issue, but given I’ve seen the same behavior on multiple drones I’m confident it’s the Pixhawk 6c. We are reaching out to Holybro to hear their thoughts on this.

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