Motor within watt and amp specs, still overheating, any ideas?

[West_Side_Flyah]

Good Evening everyone.



I'm blanking out here, both of my Sunnysky x2208 (1260) motors keep overheating. They're rated for 15 amps max and about 160 watts max, and should run WOT at around 50 degrees Celsius with various sane set ups. Here is the confusing part, my set up only pulls 13amps max at 9.9v, pulling about 135 or so watts, which is well within a safe margin of error in my opinion. My battery and esc are chillin, but the motor heats up to 135*F pretty quickly. Even at 70% throttle, or 10 amps, it still wants to run at about that temp. Only at around 50 watts does it maintain an acceptable temperature. Even at 68 watts it was trying to rise up into the 120s (F)
I pulled some timing out of it, but it just dropped max amps a small bit but it didn't do much. Both of the motors exhibit the same behavior on 2 different ESC's with the same prop and battery.


So im starting to wonder, is ~150*F normal for these small motors close to their limit?. Buddy RC notes that the coils and bearings should be good to 356*F (180*c) Seems kind of excessive to me, a street car wouldn't even take those temps, but is this just how they run? My set up should be safe at WOT for as long as I need it. Down propping isn't necessarily an option for me, but what do you guys think? Ever heard of this? Any suggestions? Should I send it anyway?

 

[sprzout]

What size prop and pitch are you running?

 

[LitterBug]

Rated props size is 8-10 inches in the 8x38 to 10x47 range. I have a bunch of these motors and regularly run them way beyond rated specs without adverse heating. (9x30 on 6S and they run warm at best) Is it possible that your mounting screws are too long and are hitting the coils inside the motor?

 

[sprzout]

I have a bunch of these motors and regularly run them way beyond rated specs without adverse heating. (they run warm at best) Is it possible that your mounting screws are too long and are hitting the coils inside the motor?

That's one of my thoughts as well, but not mentioning the prop/pitch could be part of the problem as well. How are you testing your wattage/amp draw? Are you connecting a watt meter in line, and if so, are you testing it with the prop connected? I know everyone says you should test on the bench without a prop, but this is the one time you NEED the prop on when testing or else you won't get an accurate draw for power, due to the resistance of the prop.

 

[West_Side_Flyah]

Good morning


I am conducting my tests with an orange Gemfan 10x6 connected to a prop saver. My test bench is a little square box with a 10 pound weight. For test data I am using an ebay 200 watt power meter with temperature being measured via temp gun, and my scolded finger. I know the 10x6 has a slightly higher pitch, but Im also not running it on a full 11.1v lipo (7.4 Lipo and 9.9V Life), I checked this out on the watt meter a long time ago but never thought that values within specifictions would overheat it.

Im using the included screws. They are about 3 millimeters away from the lowermost coils and they dont clear the mounting plate on the fixed section of the motor itself. I can back them out a couple turns if I use a washer, Do y'all suspect some type of electrical interferience?


9x3 on 6s? Wow!

Oh yes all this was done with the prop on, when I took the prop off, nothing seemed too concerning with regard to no load current, no load watts, or temps from running it at max rpm with no load. Sorry for omitting that.

 

[LitterBug]

9x3 on 6s? Wow!

Short bursts at that, but I do regularly fly 4S even though they are rated 2-3S.

 

[West_Side_Flyah]

Update, I found that the mount screws were brushing against the insulated motor wires, so I used some small m3 nuts as washers and fixed that. The motor was still hot, but a 2 by 3 inch piece of aluminum foil arrested temperatures a bit. I am now able to use it at 70 watts, bursting to 130. Ill do these mods to my other Sunnysky motor when I work on the plane.


I still think its running too warm, and if I hold WOT it starts getting toasty, but I think your suggestion to check the screws helped out. I topped out at about 125*F today but stopped the test there. We are headed in the right direction, if you guys have any further ideas, they are appreciated.

 

[Ketchup]

Update, I found that the mount screws were brushing against the insulated motor wires, so I used some small m3 nuts as washers and fixed that. The motor was still hot, but a 2 by 3 inch piece of aluminum foil arrested temperatures a bit. I am now able to use it at 70 watts, bursting to 130. Ill do these mods to my other Sunnysky motor when I work on the plane.


I still think its running too warm, and if I hold WOT it starts getting toasty, but I think your suggestion to check the screws helped out. I topped out at about 125*F today but stopped the test there. We are headed in the right direction, if you guys have any further ideas, they are appreciated.

Maybe it is because the motor is stationary. Motors like these are air cooled, so by running it on a bench you are stopping it from being able to effectively cool itself. It is still odd for it to run so hot, but maybe using it on a plane would let it cool. Also, the plane in flight will pull less amps and put less load on the motor than one on the bench, so that could help too.

 

[LitterBug]

Could also try a shorter prop and/or one with less pitch

 

[West_Side_Flyah]

Yeah you guys are right, in the air it will unload, and If I use a shorter prop or less volts, ill have to use it on one of my smaller planes, which is no problem. Furthermore, once I get to my pattern altitude, I wont even need to push it.



So far, I think my problem has been mitigated, big shout out to LitterBug for giving me some reference on what these motors should be able to take, and reminding me to double check those screws (the bare wire was visiable!). I think I can run this set up far better now, its still warm but temps are acceptable.


Thanks for your help!


TDLR
1. Make sure the mount screws dont hit the coils or the wires
2. Use a lower pitch
3. Aluminum heatsink or motor mount to help with heat