My APS 8072S setup acts strange - At a certain level of RPM the magnetic rotor starts to vibrate.
This is both happening when going up in speed, and when throttle is totally released and the rpm just decreases naturally.
When the vibration kicks in, the power decrease until you get above the vibration point.
It happens to both motor and they are new, so i doubt the problem is in the motors (unless APS deliver bad motors?).
I made two videos of the problem here.
Setup is VESC6, APS 8072S, 12S LI-PO turnigy graphene.
I asked if the behaviour was the same under load. The vid is obv. zeroload. The mechanical resonance RPM maybe sounds and feels scary, but its quite normal. Did u ever look at a washing machine spinning up? At a specific RPM it looks like its gonna take off, then it just settles down.
It could be the motors cans are imbalanced. If you’ve taken a motor a part, sometimes you’ll see some little blue dots of putty inside the magnets spaces. These are used to balance the motor, along with vibration detection tools to figure out where the imbalance is. The higher the speed, the worse the imbalance gets because the centripetal forces are higher at higher speeds.
Can’t say if this is your case, I would double and triple check all software/hardward first before jumping to this possibility. But I have strong feeling this might be your problem.
This exact thing happened to me with my 6374 motor last year. (There should be an old thread on this as well.)
I opened up the motor and it looked as if some of the magnets were slightly touching the stator, as there were very light marks on the magnets.
I couldn’t see why this was happening at the time, so I kept riding the board. After a while though the noise kept getting worse and changed, and eventually the motor broke down totally and it turned out that some magnets had come loose, ie I could move the with a screw driver as the glue had let go.
I got the can replaced with a new one, which solved the issue.