One motor is slow?

[HeyImMilan]

The other day I managed to crash my drone into black sand, one motor started spinning very slow and the others were still spinning fast.

So I assumed it was just the black sand slowing it down stuck in the motor, so I disassembled the drone and took the motor apart, cleaned all the sand out and the motor was spinning freely when pushed with my hand. But when I turned the drone on, that one spun very slow.

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[With The Birds]

No ESC error reported?

Given the issue started with the crash and cleaning the motor didn't resolve it you have either cooked the motor windings or the inverter stage in the ESC. How did the coils look (condition of insulation)?

 

[HeyImMilan]

No ESC error reported?

Given the issue started with the crash and cleaning the motor didn't resolve it you have either cooked the motor windings or the inverter stage in the ESC. How did the coils look (condition of insulation)?

Nope no errors at all on the dji app. Everything looked normal inside the motor and looked just look all the other motors that are working.

 

[With The Birds]

For the time it will take I would just swap the motor with the front right. If it still spins slow its obviously a motor issue, if it runs normally you are looking for a replacement mainboard.

 

[HeyImMilan]

For the time it will take I would just swap the motor with the front right. If it still spins slow its obviously a motor issue, if it runs normally you are looking for a replacement mainboard.

Okay cool ill try that, hopefully it's just the motor. Even though I have to get those shipped to NZ and that takes a whole month haha

 

[HeyImMilan]

For the time it will take I would just swap the motor with the front right. If it still spins slow its obviously a motor issue, if it runs normally you are looking for a replacement mainboard.

Oh yeah it appears that one of the coils looks kinda spilt into by one of the screws.

 

[With The Birds]

Oh yeah it appears that one of the coils looks kinda spilt into by one of the screws.

I was going to ask if you had managed to butcher any of the windings with the longer prop guard screws but it seemed the issue related to the crash.

If that’s the case I would be checking all the motors.

 

[HeyImMilan]

Yu

I was going to ask if you had managed to butcher any of the windings with the longer prop guard screws but it seemed the issue related to the crash.

If that’s the case I would be checking all the motors.

All motors checked, just that one that looks butchered. Would piercing the copper windings really effect it that much? I'll swap the motors around too, to make sure it is just the motor

 

[With The Birds]

Piercing more than one windings creates potential for an interwinding short, it may easily go unnoticed. Break the windings anywhere and you loose four field windings (motor has 12 coils, three groups of 4 in a series wound delta connection), you have basically dropped a phase and the motor would run like a pig if the ESC did not enter a protection mode. What you are likely seeing is the ESC constantly trying to start the motor on two phases.

 

[HeyImMilan]

Piercing more than one windings creates potential for an interwinding short, it may easily go unnoticed. Break the windings anywhere and you loose four field windings (motor has 12 coils, three groups of 4 in a series wound delta connection), you have basically dropped a phase and the motor would run like a pig if the ESC did not enter a protection mode. What you are likely seeing is the ESC constantly trying to start the motor on two phases.

Thanks for that answer, so it would just be best to buy a new motor?

 

[With The Birds]

Thanks for that answer, so it would just be best to buy a new motor?

Bingo..... And hope you haven't cooked any of the inverter FET's for the corresponding speed controller. It is unlikely if the motor has gone open circuit however.