Dead Motors?

[LeeT]

I crashed my DJI F450 breaking two arms. I replaced the arms hooked up the motors to the ESC and when I went to bench test, both motors turned very slowly and were notchy. It seemed like they were turning from pole to pole one step at a time. I traded motors to make sure the ESC that isn't bad, and it isn't. I checked with an ohm meter for shorts and opens. They measured .3 ohms across the motor wires, same as the good ones.

Any suggestions on how to fix these, or am I on the hook for two new motors? If so do I need to replace with the same brand (T-motor), or can i replace with a Sunnysky that is the same value?

Thanks,

 

[Electro 2]

You might check the soldered joints at the bullet connectors on the motors as these are frequently a weak point. Your description sounds as if the ESC can't start-up the motor because it doesn't see a timing pulse returned from one or more of the three phases. If this isn't it, wiring inside motor housing could be broken, as well. Dunno if you'd want to tackle this, as it's far more difficult to deal with. (I'll stay here at the other end of I-4, maybe I won't crash, LOL.)

 

[gpforet]

Sounds like hosed motors. Or you have debris in the motors. The clearance between the PMs and the coils is pretty tight. Debris could be binding the motors. How well do they turn by hand and can you feel a difference between the motors that work well and the ones that don't? If it's just debris you can wash it out with a spray solvent but that could remove lubricant in the bearing. I lost 2 motors in a bad crash when the side of the motor casing pushed in a caused interference with the motor rotation.

 

[CdA D]

Might want to make sure that motor shafts are straight. They wouldn't need to be off by much. That's if you don't find anything else wrong.