Cooling an open motor (statorade useless?)

[leoms]

Hi all,

I'm having some issues with my mid-drive outrunner motor which I think are heat related. After running it hard up a hill (high torque, low airflow) it emitted a little wisp of smoke. I backed off, of course, and things seem OK, and I'll be gentler. But in an ideal world I'd improve its heat dissipation.

Obviously one option is to improve airflow. Seems like statorade is no good in an open (outrunner) motor, it would collect tons of dirt, right? Any other low-hanging fruit to cool the coils on an outrunner? It's a 1.5kg-ish motor, allegedly 5kW (not that I really believe that).

Thanks everyone!

 

[lnanek]

Add a cooling fan?

 

[amberwolf]

As noted in your other thread,

Motor skipping (and burning out)

I have a custom made mid-drive bike. When I punch the throttle at low speed, there's a loud popping noise and the motor, I believe, jumps/backfires/skips. After being too casual about this, I discovered smoke coming off of a blackened-looking stator post (sorry if that's the wrong word, the...

endless-sphere.com

the first thing to do is to use the parts within their limitations. If it's overheating, you're not doing that.

If you "think" they are heat-related, but haven't measured temperatures, or at least done a "hand check", then you don't know what's causing the problems, and before you pursue cooling options, you should find out the cause, so you don't waste time on the wrong problem.

If you *are* having an overheating problem, and you're determined to use the parts outside their limits, you're going to have to add cooling. There are quite a few threads about cooling RC motors and various shapes of controllers (since it could be your controller being overstressed, too or instead); most of them start with airflow fixes (fans, fins, heatsinks, etc); some go right to water or other liquid cooling.


BTW, you should check where the smoke came from. If it's from a winding, it may have damaged the insulation enough to allow shorts (complete or partial) between windings or phases, or to the stator itself, etc. If it's from the actual phase wires to the controller, you could end up with a short directly between those. (these things usually blow up controllers)

 

[scianiac]

How's your gearing vs the motor Kv and voltage? A bit more RPMs and you may be able to get the same power with less resistive losses and less heat generated.

 

[leoms]

Thanks all - especially after reading amberwolf's message (and their responses on my other thread), I don't think this is a straightforward heat issue. I do regular finger checks on the windings themselves and they never feel hotter than about 150F, and the wires and resin in the windings are good way above that. Gonna investigate the possibility of a short before I focus on cooling.