The mystery of the screaming motor [SOLVED]

Flipsky 6.6dual, sensored FOC mode
75 motor current max
-60a motor current max brake
120a absolute max
50a battery max
-20a battery max Regen

Under load one of the motors scream. And I’m totally stumped. Once you get moving it’s just fine. What have I done wrong? (besides buy a flipsky)

Sliding belts?

Im def no expert but not necessarily the dolphin’s fault. I think it would be good to include what motors you’re using (looks like maytechs 6374) and what battery you’ve got. Maybe broken sensor, can you switch the screaming motor with another that you know is working?

Interesting notes. It won’t scream on the bench when I hold the can.

However when I press up on the keyboard one motor will go to 90% duty, the other won’t go over 5%. Sometimes if I time right arrow with up arrow it will spin up to 100%.

I’m guessing broken sensor as well now. So to test that theory I put it in sensorless mode. Same thing. Weirdness abounds.

Check your phase wires. I had a connector melt the solder loose on the vesc side and honked like a horn but wasnt easily visible because it didnt melt the heat shrink enough to make it an obvious culprit.

Tore the motor apart and checked continuity on all phase wires. Looked good. Put it all back together, spun up good.

Ran detection again, was super shaky on hall sensor detection. And this broke the up arrow spins up to full power thing again.

Cool, so it’s a hall sensor detection issue. Cranked the hall sensor detection field from 10a to 30a, ran detection again, motor was much less shaky and looked good.

This seems to have fixed it. And it’s the dumbest fix I’ve ever seen. May this thread serve as a lesson to future builders who use the search tool.


That sounds like a bms cut of sounds, I noticed I hear the same sound when I push my bms past its discharge cutoff. What kind of battery are you running and is the bms wired for discharge?

10s5p of NCR20700B, charge only bms. This is a factory LaCroix that someone took a little swim in the ocean with (not me). Rebuilt motors with new bearings and replaced all electronics (battery didn’t get wet).

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Hmmm, so that sound is a sensor related issue you think huh? Now that I think about it, it makes sence to me. Ever since I started running my motors sensorless, I dont have that issue…