Advanced motor temps.

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This came up & I wanted to know if there was a difference in running temperature between a motor that has suffered the Deadly- "Squeal of death", caused by falling over & prop.sticking in the sand vs a stock motor.

The flight - 7 min. of Litchi & another 8 min. of just bombing around a 850' open field,
Return to home & hand caught- motor temps immediatetly taken by a infrared handheld, pointed at side of sliver motor shroud.
Any slight changes are distance I held the gun from motor casing , I think.
Front motors-
left- 69-71.5 F.
right- identical to left- 69.5-72 F.
Rear left- 70-72 F.
rear right- -74-76 F. (squealer!)
Any thoughts on what temperature one should start worrying about motor life or is there such a motor tell?
 
The motors really only have one moving/wearing part or assembly, the bearings.
I have a motor on a CP-heli with 600+ hours and no problems yet.

I don't have temp data like you but the rear(s) being a tad warmer is not alarming. They work more when flying forward.

I hand check for similar temps. all the way around and call it done.

Since you have data you should be able to tell if any begin to increase over the others over time.
All else being equal this would seem to indicate increased load due to bearing failure.
 
My flight log yesterday showed 130 degrees Fahrenheit when it landed. Didn't see any warnings, but it made me concerned. Temps were around 90 degrees and humid.
 
Your battery?
 
If it squeels (and on top of that, is running hotter), replace it ASAP. Both point to increased friction, possibly because of damaged bearings or a bent motor shaft. This friction can cause the ESC to lose sync, and Really Bad Things will happen when that occurs in flight. Phantom motors are pretty cheap, just replace it.
 
I have a motor on a CP-heli with 600+ hours and no problems yet.

You keep saying that as if its relevant here. How many crashes did your heli motor suffer over those 600 hours ? Im guessing ~zero. And how thick is the motor shaft? Im guessing at least 5mm. The phantom motor has 3mm shaft, thats as thin as on my 250mm mini racing quads with just 5" props. Lastly, is your motor connected directly to your blades ? Nope, so even if you do crash it, other components will take the hit first. No so on multirotors.

PS: here is what happened when I tried to remove the windings on a bad motor (trying to make a prop balancer) using pliers :

9qx4bZL.jpg


Im really not particularly strong, these things are NOT tough. They are designed to be super lightweight.
 
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Lots of questions lately about motors, lifetime, etc.

Reread the OP, esp. the last 11 words.
 
Ambient temp. last night here was 68 F.
Vertigo- If you were talking about my "squeal of death" it only happened that one time, when I had rear prop, hit/stick in sand on landing, for 4-5 seconds till I shut her down. Believe me, if it squealed when flying, idling, etc I would replace right away as you suggest.
 
That squeal, when bound, was the motor itself oscillating similar to the start-up sounds not the bearings
 
Vertigo- If you were talking about my "squeal of death" it only happened that one time, when I had rear prop, hit/stick in sand on landing, for 4-5 seconds till I shut her down.

ok, I misunderstood that. That squeeling is the esc losing sync and that should not be a problem. If it spins freely and doesnt sound weird in flight, a few degrees difference likely means nothing. Just the direction in which you yaw or wind will make some motors work harder.
 
That hi-pitched squeal, that is emitted when a prop is stuck & can't rotate,
does this cause any damage, accelerated wear?
Oh, I just read Verigo's explaination,
thanks guys
 
My motors always seem slightly warm after a flight but never hot.
air temp here is around 30 deg C
 
This came up & I wanted to know if there was a difference in running temperature between a motor that has suffered the Deadly- "Squeal of death", caused by falling over & prop.sticking in the sand vs a stock motor.

The flight - 7 min. of Litchi & another 8 min. of just bombing around a 850' open field,
Return to home & hand caught- motor temps immediatetly taken by a infrared handheld, pointed at side of sliver motor shroud.
Any slight changes are distance I held the gun from motor casing , I think.
Front motors-
left- 69-71.5 F.
right- identical to left- 69.5-72 F.
Rear left- 70-72 F.
rear right- -74-76 F. (squealer!)
Any thoughts on what temperature one should start worrying about motor life or is there such a motor tell?

temperature of the motor is limited by the winding insulation class and neodymium magnet type (bunch of them on the inside of bell of motor). I have found no documentation on magnet type DJI uses, but M or H type are common with limits of 100 and 120C respectively. For insulation class, B or F are really common and have a limit of 130 and 155C respectively. The windings will get hotter than the motor. High temps will weaken the magnets or short the windings. A shorted winding will be WAY hotter and will likely turn at a different KV than the others (should be very noticeable in flight). Weakened magnets will cause efficiency losses, but if the bell got hot enough to crap a magnet, you likely would have noticed that.
 
I have a P2V. I have one of those laser deals too. I took my motor temps too. When I did it a couple months ago, three of them were in the upper 70s F and one was in the mid 80s F. Obviously the temp will vary depending on air temp. I don't have any obvious problems. Hope this helps.
 

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