Troubleshooting magnetic resistance in 6384 outrunner

Build, Repair & Mod
1

Hi, im seeking some help to troubleshoot the following problem:

I have a home made integrated mast - its an alloy Axis 19mm with a Saite 6384 - last night i was having quite a nice session when i fell off rather benignly - when I went to start again the motor had developed a noise and would cut out above 50% throttle - on the beach i ran a log analysis via blutooth and found the cut outs are an overcurrent warning. When I go to hand turn the motor I get what really feels like magnetic resistance - its not grindy or sticky - just a smooth resistance. I ran comprehensive tests with my meter on all phases and no matter what cannot find a short in the system, the resistance between phses seems to be constant accross all phases. I have a brand new spare motor with me and when I turn it by hand it turns extremely freely with sliught cogging - the fitted motor does not display any cogging just a clean drag. Im at a remote beach and dont have tools here to do a tear down and replace the motor but I did swap bells over and the brand new bell behave the same way as the older bell on the integrated mast - at least eliminating the bell as an issue.

Any advice greatfully received !

2

When phases are shorted you get this smooth heavy “resistance” when turning the motor.

Is it possible that you have a short in one (or some) of the transistors in the motordriver/ESC?

How does it feel to spin the motor if you disconnect the phasewires from ESC?

If you short all the three phases on your spare motor and try to spinn it, does it feel the same?

3

I Have a brand new spare motor with me but no tools to mount it in the mast - what I did do was plug the good motor into the esc and it runs fine - so not an esc issue, I ran exhaustive tests on the mast and simply cannot find a short. Yes with the good motor when I touch two phase wires together it gets harder to turn as per normal. With the mast disconnected from the ESC the motor has a smooth resistance as if the phases are shorting together somewhat.

4

How did you test this? Have you tested the windings of the motor?

All three must be shorted to get the smooth feeling. Does the motor in the mast feel the same when spinning as the spare with all three phases shorted?

5

I tested for shorts with my multimeter - testing continuity between each phase and various metal parts on the mast i like the baseplate bolts, the motor bell, the mast base etc - I also tested resistance between phases and they are all in range and even

6

No, when I short all three phases on the spare motor its much harder to turn that the fitted motor.

7

The resistances phase to phase is to low to measure accurately enough with a normal multimeter if you have phase to phase shorts (or partial shorts). You need to have some lab equipment to measure that. For instance I usually run maybe 10 amp DC phase to phase with a powersupply and then measure voltage to calculate winding resistance.

You can have shorts between the windings (or even phase wires) without it being a short to other metal parts.

And the fitted motor turn smootly but with some resistance even when ESC is disconnected?

If that is the case my best guess is that you have shorts within the motor winding.