motor burn out on shut down - wondering if any one has had this happen

[jhardway]

I have a hexa, built it in November, and have been flying it, I would not say it has a lot of time, I am around 10 hours - 50 flights, the motors are Tiger 3515's, esc's are Maytech 40amp opti's not bec (power pin pulled to the flight controller on all ESC's) , and the flight controller is a WK-M, the receiver is a jr DSM 2.4, along with the transmitter jr 11x24

After a flight today I landing the helicopter and shut down the motors. all the motors except m4 shut down, the m4 started twitching, the longer it twitched the more is started to engage. I looked over my transmitter to make sure everything thing was cut back to shut down point. About 10 seconds into the twitch the motor started spinning on its own, about five seconds later I was able to unplug the battery.

Immediately I started to look over the motor to see if anything was not right, I touched the esc and it was cool to touch, while the motor itself was hot, and it had a burning smell going on.

I pretty sure the motor is gone and I am not willing to fire it up to see. However I can also feel when I spin the motor by hand its not as magnetic resistant as the other motors are.

I have not touched it in any ways yet, but after looking at the esc/motor bullet connector they were all fine and way from each other, the esc power connections are solid.

Any ideas, I am wondering if anyone have had this type experience/ heard of it before, if so what was the problem, is it something in the motor, ESC, Flight controller.or else where.

Since it build in November the copter has flow great, nothing to report in out of ordinary situations.

Look forward to hear from you all.

thanks Jack

 

[helloman1976]

I have a hexa, built it in November, and have been flying it, I would not say it has a lot of time, I am around 10 hours - 50 flights, the motors are Tiger 3515's, esc's are Maytech 40amp opti's not bec (power pin pulled to the flight controller on all ESC's) , and the flight controller is a WK-M, the receiver is a jr DSM 2.4, along with the transmitter jr 11x24

After a flight today I landing the helicopter and shut down the motors. all the motors except m4 shut down, the m4 started twitching, the longer it twitched the more is started to engage. I looked over my transmitter to make sure everything thing was cut back to shut down point. About 10 seconds into the twitch the motor started spinning on its own, about five seconds later I was able to unplug the battery.

Immediately I started to look over the motor to see if anything was not right, I touched the esc and it was cool to touch, while the motor itself was hot, and it had a burning smell going on.

I pretty sure the motor is gone and I am not willing to fire it up to see. However I can also feel when I spin the motor by hand its not as magnetic resistant as the other motors are.

I have not touched it in any ways yet, but after looking at the esc/motor bullet connector they were all fine and way from each other, the esc power connections are solid.

Any ideas, I am wondering if anyone have had this type experience/ heard of it before, if so what was the problem, is it something in the motor, ESC, Flight controller.or else where.

Since it build in November the copter has flow great, nothing to report in out of ordinary situations.

Look forward to hear from you all.

thanks Jack

Well we can only speculate but I know electric motors pretty well and typically when you see something like that it's from over-amperage OR high internal heat. A good test of an outrunner is to spin it and see if it has resistance with no power applied to it, it should "ratchet" so to speak so in other words not perfect movement more like it's going from one magnetic "notch" to another. If you don't get this, replace the motor and it's as simple as that. Make sure you re-program you ESC as sometimes it could be a gliche in the software and re-writing the code to it can fix the corruption or whatever. Again, these are just speculations based on educated knowledge of wound motors. Hope that helps...

 

[DennyR]

It's definitely in the ESC as one of the phases has been energize at the wrong moment in time. The cogging effect wont tell you anything as it is a function of the magnets and the poles, it would do that even if there were no windings. If motors overheat then some of the magnetic field can get lost. I would replace the motor and the ESC.

It is worth dismantling the motor just to see what has happened. It would not be the first time that a winding has come off and get trapped between the magnets.

 

[jhardway]

ya I am replacing both, and its best, I will see if the motor dealer will do something about it, He has in the past. The esc I am ok with but the motor kinda bumbs you out, its pretty expensive part, but that is part of the world we play in.

 

[helloman1976]

ya I am replacing both, and its best, I will see if the motor dealer will do something about it, He has in the past. The esc I am ok with but the motor kinda bumbs you out, its pretty expensive part, but that is part of the world we play in.

Hey, it's better than replacing the whole thing because it fell into the ocean or got lost because a motor failed in flight. I do the spin test to see if the motor is still good, works every time. If they lose magnetism you'll see it in the spin test. Try it now, spin a good motor and a bad one and you'll be an expert Another way to check them is when they are energized and there will be even more resistance then, be careful though as they're armed. If they are getting hot in flight, check when you land immediately, then they can burn out the windings etc. Keep in mind it could just be a bad unit too...

 

[Ttelmah]

It is perhaps worth 'being aware', that if a motor has been working hard, and you then quickly shut down, it will get hotter. The units we use, rely on the air flow for cooling, and if the core and coils have been working hard, sudden shutdown can lead to overheating. Normally it is not a problem for copters, since we tend to descend (using less than high power), and the motors have a chance to cool. However I've seen a guy with thermal telemetry on his motors, who did some significant aerobatics, and when he landed, the motor temperatures shot up.....

Best Wishes

 

[jhardway]

Ttelmah, you know I can see what you are talking about and never would have thought of it, but over all the motor was not over worked in the weight game. However I have to give a shout out to MontoRC (North American Tiger distributor) - Since getting into this I have bought all my Motors and ESC's from them and every time I have had a problem or question they have been on the ball.

In this case after quickly talking to them, they're replacing the motor, and in the past when I had a question on my motors he's always been right there to do the right thing. Two thumbs up !