Scorching hot motors???

[PropSpin]

I just finished up a flight a few hours ago that included climbing to 400 feet, flying out about 2000 feet, hovering for a few minutes, flying back, and then trying out some of the intelligent flight modes before finally landing with about 10% battery left. I actually hand caught it and in the process one of the motors brushed my arms and it was hot!

As it turns out, the rear motors were very hot (both about the same temp), and both of the front motors were scalding hot to the point of being capable of causing first degree burns if held 5 to 10 seconds.

It's very concerning to me that the front motors got as hot as they did, and it's strange that the front motors were so much hotter than the rear.

Is this typical? The ambient temp was ~90 deg F, and in this case the AC is an M2P.

Next time, I'll pack my infrared temp thermometer and get a reading.

 

[Former Member]

You can get a first degree burn at 110° but only if you keep your fingers on the source for a while.

If I were you, I would keep your temp gauge handy and hover it on the next flight. The motors will be hot by 2-3 minutes. I would land it and take a reading.

Ways to cool down Mavic Pro motors

Anyone have any know to work techniques to help cool down motors? Just flew a test run for the birdside amp mod, it’s hot as hell here in Houston. No way I can carry extra batteries this summer without burning a motor or two out and falling from th sky. Very hot to the touch. Anyone know a way...

mavicpilots.com

 

[PropSpin]

You can get a first degree burn at 110° but only if you keep your fingers on the source for a while.

If I were you, I would keep your temp gauge handy and hover it on the next flight. The motors will be hot by 2-3 minutes. I would land it and take a reading.

Ways to cool down Mavic Pro motors

Anyone have any know to work techniques to help cool down motors? Just flew a test run for the birdside amp mod, it’s hot as hell here in Houston. No way I can carry extra batteries this summer without burning a motor or two out and falling from th sky. Very hot to the touch. Anyone know a way...

mavicpilots.com

Yeah, can't really tell how hot for sure other than to say that at 3-5 seconds on the front motors was painful. Rear motors, I could hold on to them indefinitely, but they were still really hot. It is really strange to me the temp discrepancy between the front and rear motors. I figure that the drone should be balanced and the motors all do the same amount of work...

I should have a chance to check it out tomorrow with the temp gun.

BTW, where did you get those max temps in the thread that you linked? I expect they should be close for the M2P?

 

[Former Member]

An easy experiment would be to swap your props, front to back and back to front and see if it changes. You should really wait until you temp the motors with a gun to see if there really is a problem.

A more complicated problem might be that your front or rear arms are not aligned (aimed) correctly, and that is forcing the front motors to work harder to keep up with the rears. The rear arms fold up and down, that might be the more likely set to be out of alignment. If the rear arms are overextended upward more than they were when they were set at the factory, the fronts will try to keep up, and work harder.

Maybe you can post your flight logs to see if the front motors are drawing more current than the rear ones. More current than they are supposed to have at a given attitude will make them run hotter.

Front motors tend to run hotter then rear anyway. You would think it would be the opposite because the fronts are upwind, but its just not the case.

Where do I get the max temps from? I temp pretty much every drone that I repair, paying more attention to the ones where I replaced an arm. I want to make sure none of the other motors were damaged, even though they might look fine to the naked eye. I accept an anomaly of 5° difference in all the motors as normal. Also, even though I use new parts, you never know when one is factory defective. I know from experience if a motor starts whining, vibrating, running alot hotter than the others, or smoking, theres something wrong.

 

[PropSpin]

I flew it today, but the ambient temps were about 10 degrees cooler, probably around 82 F. I took the temps, but they're just ballpark, for several reasons. First, I just guessed the emissivity for the housings - my manual said that oxidized aluminum was .30, so that's what I set mine to. I'm assuming the housings are aluminum, and they have a brushed appearance, so...
The second reason is that by the time I started taking real readings, it was about 2 minutes after "motors off" so they had a chance to cool a little. I initially had readings as high as 318 F on the front motors, but I quickly realized that the LEDs were interfering - I hadn't powered the drone off. Also, I'm not sure how accurate my gun is at the close range I was using it which was .25 to .5 inches.

Anyway, my before flight, temps were ~82.5 and my after flight temps were as follows:

Front: 130 - 140 F given the readings from the gun
Rear: 110

Bottom of front motors: 125
Bottom of rear motors: 100

With yesterday's air temps of 90-92F it could easily have been 150+ for the front and 120 for the rear.

BTW, the arms look just fine so that shouldn't be a problem. I'm a little concerned about this - I guess I'll just have to keep an eye on it. Maybe contact DJI about it and see what they say.

Finally, I came across the following. Apparently others have noticed this too, and like you said, the front motors are running hotter.

Hot Motors!

Those motors get hot to the touch! Not burning, but I don't recall ever noticing this heat on my MavicPro. As I was packing it up the M2P after flights I assumed it was heat from the fuselage I was feeling, but then noticed it was each of the motors. Hot to the touch. Why do you think the...

mavicpilots.com

2 motors run VERY HOT

Hi 2 of the front motors now run very hot, ALOT hotter than the back 2. Underneath the motor is very hot as well. I have had no crash or anything to cause problem. It fly perfectly, hover in spot perfectly. I just notice motor very very hot at end of flight. Previously all 4 slight warm but...

phantompilots.com

 

[Jeffm912]

Those temps sound about right after a full flight, depending on how you fly. 175* is still safe for the motors, I wouldn't worry until they are around 200*.

Jeff

 

[Former Member]

Anyway, my before flight, temps were ~82.5 and my after flight temps were as follows:

Front: 130 - 140 F given the readings from the gun
Rear: 110

Bottom of front motors: 125
Bottom of rear motors: 100

All normal.

 

[PropSpin]

Those temps sound about right after a full flight, depending on how you fly. 175* is still safe for the motors, I wouldn't worry until they are around 200*.

Jeff

Thanks for the feedback - I'm curious though where you're getting your info from are these figures based off of what you've seen on your own drones, or from somewhere else?

 

[Jeffm912]

Thanks for the feedback - I'm curious though where you're getting your info from are these figures based off of what you've seen on your own drones, or from somewhere else?

Being into fast electric racing since 2002, and an electrical engineer. It happens!

Jeff

 

[WithTheBirds]

Thanks for the feedback - I'm curious though where you're getting your info from are these figures based off of what you've seen on your own drones, or from somewhere else?

The insulation on the magnet wire in the field windings should handle at least 150deg C, probably higher. Magnets might be as low as 85deg. The biggest issue is probably the adhesive that holds the magnets on the bell and the propensity for the bearings to loose lubricant. Increased operating temperature increases IR losses and contributes to more heat. They seem to stabilise at uncomfortably warm (for fingers) however we should be comfortable that temp is within the design tolerance. The alternative would be to use a bigger motor operated with less efficiency. Something we don’t want if we are interested in flight time.