Hot motor

Sami Rautaneva · Mar 31, 2017

I had one motor going hot. After two flights it failed. It went so hot that it melted the plastic under the motor. Fortunately, H flies pretty good with 5 motors. One thing that seems to indicate incoming motor fail is that when you start or stop the motors, the failing motor is not starting or stopping in sync. Propably caused by the friction of bad bearing.

ArnhemAnt · Mar 31, 2017

Sami Rautaneva said:
One thing that seems to indicate incoming motor fail is that when you start or stop the motors, the failing motor is not starting or stopping in sync. Propably caused by the friction of bad bearing.

From previous experience with my own builds, if a motor is not starting or stopping in sync then this is usually attributed to the ESC and not the actual motor. I wonder if the 'hot motor' is actually a bad ESC? This can certainly happen if you do crash and the motors are still trying to spin - as was described earlier in this post.
If it were me, I would be swapping both the motor and the ESC, so that I ruled out both options.

ThunderChicken · Mar 31, 2017

PatR said:
I don't know how Yuneec establishes power distribution for the H but ThunderChicken has a great point. The speed controller for that motor could have taken the hit when the prop broke.

Especially since these motors are using transistors instead of brushes for commutators. If you stall a brushed motor the brushes will start to heat up quickly.
Unfortunately Yuneec did not make these user repairable. The ESC is the main board and all of the ESC's are on one board. It is surface mount to boot.
Here is a photo of that board.

Sami Rautaneva · Mar 31, 2017

ArnhemAnt said:
From previous experience with my own builds, if a motor is not starting or stopping in sync then this is usually attributed to the ESC and not the actual motor. I wonder if the 'hot motor' is actually a bad ESC? This can certainly happen if you do crash and the motors are still trying to spin - as was described earlier in this post.
If it were me, I would be swapping both the motor and the ESC, so that I ruled out both options.

In my case, it was definitely the motor. After failure, you could feel that the motor does not rotate as it should. Yuneec replaced the arm and the motor. (This incident happened last July)

PatR · Apr 1, 2017

Thanks T.C. I suspected the ESC's would be board mounted. Less space and expense required.

jlwilder40 · Aug 20, 2017

Are these motors 3 phase a.c.?

AH-1G · Aug 20, 2017

Yea change it out, that's like flying a plane with one of the two magnetos out then attempting cross country.

ThunderChicken · Aug 20, 2017

jlwilder40 said:
Are these motors 3 phase a.c.?

Not A.C. but D.C. pulses. It is also is variable frequency.(Pulse width) The only thing about this three phase is power is delivered to one wire at one a time or another. It is really just a stepper motor.

kai_bcn · Aug 22, 2017

One of my motors overheated every flight ( could not touch it with my fingers ) and several flights later I could not get my prop off anymore. Again several flights later the engine stalled in flight and I had to land on 5 motors with wind. Almost tipped over at landing so I hand caught it and that is scary with 5 motors only. I would definitely change that motor asap. I would assume it is about to die anyway.