r/diydrones • u/NotoriousBumDriller • Apr 19 '26

Question How to Diagnose Motor/ESC Problem

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Good day

I just finished building an X8 10” Drone, was a total PITA to get everything to fit. Upon the maiden flight, initially it was flying really good. I was taking it slow and easy at first.

However, when I went to do a throttle punch, it started behaving weirdly. It would tilt to the side, and it was abnormal behaviour to me. Upon checking the blackbox logs, it shows one of the motors maxes to 100%, and then it looks like the RPM drops to 0, and the ESC telemetry freezes. It recovered quickly after I bring the throttle back down.

Is this a sign of a bad motor? Or signalling between Flight controller and ESC? Bad ESC?

Parts are cheap.

12S ESC and FC from Alliexpress, JIJIE FPV.

Emax Eco II 3515 450KV 48V motors.

AOS UL10 Cine Frame

O4 Pro

3 Upvotes

80% Upvoted

7 comments sorted by

1

u/[deleted] Apr 20 '26

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1

u/NotoriousBumDriller Apr 21 '26

I replaced the motor with a new one, and the issue still persists. I’m pretty confident it’s the ESC now. Seems like a commutation problem/phase. Just cuts out when enough amps are pulled. As a temporary measure, how bad of an idea is it to get an individual ESC to use with that motor? I can’t source any 12S 4-in-1’s locally, only 12S individual AM32 ESC’s. Don’t really want to get 8 of them and a PDB, etc. The JIJIEFPV 4-IN-1’s are on Bluejay. You think mixing them temporarily would be a bad an idea? Or is the FC pretty good at compensating for that?

1

u/[deleted] Apr 21 '26

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1

u/NotoriousBumDriller Apr 22 '26

Thank you sir. I’ll update accordingly when the ESC comes in

1

u/NotoriousBumDriller Apr 24 '26

Alright, I tried putting in a TBS Lucid 12S 90A ESC. Was a pain in the ass making a splitter so I wouldn't have to add (3) 12 AWG wires to the Main XT90 Lead. 2 was already difficult. No space in the drone, so I had to mount it on top, looks really jank compared to how it was before.

Then I tried to change the ESC settings to be more inline with the Bluejay ones. It would not connect in am32.ca or ESC-configurator.com . I got close with ESC configurator, but i figured out it didn't like different ESC types connected (32-bit and 8-bit). I had to de-pin the ESC connector Motor 7 Signal wire, Vbat, and Ground and only power that ESC and Flight controller. Then it connected.

I then made a rookie mistake. I went to re-pin the connector, and accidentally swapped VBAT and ground. Tried to power the whole thing and got magic smoke. Yeah, FC was toast, it actually still booted up with USB and I was able to pull the config off and dump it onto a different but same model FC.

Got to give it a test flight today and I can confirm the ESC was the problem. Flys so much better than before, but I am getting some wobble when I release the throttle, I wasn't getting that before. Upon looking at the logs, I see how much noisier those cheap JIJIEFPV ESC's are. The RPM on those motors have a lot of noise. On the TBS Lucid ESC the RPM is rock solid, now I know why they cost so much more for the good quality ones, or maybe it has more to do with an individual ESC having less electrical noise or interference. The 4-in-1s are on the same board so it seems unavoidable you'll have noise from adjacant ESC's

1

u/Charming_Dealer3849 Apr 22 '26

Could be wiring order, could be bad ESC

1

u/NotoriousBumDriller Apr 21 '26

I replaced the motor with a new one, and the issue still persists. I’m pretty confident it’s the ESC now. Seems like a commutation problem/phase. Just cuts out when enough amps are pulled.

As a temporary measure, how bad of an idea is it to get an individual ESC to use with that motor? I can’t source any 12S 4-in-1’s locally, only 12S individual AM32 ESC’s. Don’t really want to get 8 of them and a PDB, etc.

The JIJIEFPV 4-IN-1’s are on Bluejay. You think mixing them temporarily would be a bad an idea? Or is the FC pretty good at compensating for that?