Definitive Tests on the Heating and Cooling of Hub Motors

[neptronix]

Most of the heat on the motor is on the edges of it.

You should consider getting a hubsink if all you need is minor air cooling.

 

[Cowardlyduck]

I'm thinking about cutting out a space in the side cover for a copper heat exchanger (copper conducts heat better than aluminum by 50%). I first need to measure how much space I will have - because the cassette is also mounted on this side. If there is not enough space, perhaps I will add a flat copper plate. or perhaps three flat plates in the shape of a "pizza slice" - only three narrow plates to maintain the stability of the cover. installation, most likely with screws + sealed with silicone resistant to high temperatures. I'm analyzing this idea - unless someone thinks it's an idiotic idea, I'm listening
edit:
or maybe placing there only flat plate of copper will be great. I mean wery thin to get very good heat transfer. on this side most of you have motor windings so place for put there thin copper exchange is good.
Better than a copper plate, it could be to add a membrane that allows air to pass through but does not allow water or dirt to pass through, but I have no idea if they exist.

If FF + Hubsinks isn't enough, the next best option is forced ventilation. You don't have to conduct heat if you simply remove it:

Cooling fans inside Hub motors

Hi all, I've posted about this a few times in other threads, but I think it deserves a thread of it's own as I believe the idea has merit and I plan to try it in the future with my Crystalyte HS4065 once I repair it. If you take a look at Crystalyte Hx series motors (and many other motors)...

endless-sphere.com

Cheers

 

[E-HP]

I'm thinking about cutting out a space in the side cover for a copper heat exchanger (copper conducts heat better than aluminum by 50%). I first need to measure how much space I will have - because the cassette is also mounted on this side. If there is not enough space, perhaps I will add a flat copper plate. or perhaps three flat plates in the shape of a "pizza slice" - only three narrow plates to maintain the stability of the cover. installation, most likely with screws + sealed with silicone resistant to high temperatures. I'm analyzing this idea - unless someone thinks it's an idiotic idea, I'm listening
edit:
or maybe placing there only flat plate of copper will be great. I mean wery thin to get very good heat transfer. on this side most of you have motor windings so place for put there thin copper exchange is good.
Better than a copper plate, it could be to add a membrane that allows air to pass through but does not allow water or dirt to pass through, but I have no idea if they exist.

If you do this, please add a temp sensor on the stator and gather some baseline data. Then it will be a way to see the results. With liquid cooling, while messy, it’s easier, conceptually, to see why it would be very effective at heat transfer. Under load, the stator temp could quickly spike over 100c while the side covers remain barely lukewarm. 50% greater heat transfer sounds impressive until you compare it to how much heat the weakest link, air, can transfer from the stator to the side cover.

 

[amberwolf]

@kk64; This page may be useful to you; I found it in a search for something completely different. Haven't read all of it, so don't know the conclusion.

Bafang CST – Oil Cooling

I got a ‘like new’, used 20″ Bafang CST geared hub motor from Ebay. The seller stated it only ran 170km. Definitely no exaggeration, since it still turned with noticeably resistan…

etrike.wordpress.com

 

[Bullfrog]

Yeah, it's gotten quite cumbersome to find the actual test results scattered amongst this thread for comparison purposes, and we could benefit for sure by having an index post at the beginning that has direct links to each of the individual posts with test data. I may try to make that happen, and in the meantime will try to include the previous test data in with the new one.

On that front, lots and lots of new test data with the MXUS motors on the way, this here is what is spinning in the wind tunnel right now.
View attachment 180862

Justin's Pic:


I like it! IMO it would be better to to remove the heat from the stator and reject it directly to the atmosphere than it would be to conduct it to the shell and then reject it to the atmosphere.

I have been thinking about adding a scoop on one side of my bike to catch the air while riding and direct it towards the motor. I hope to drill holes close to the ID of the side cover on the same side as the stationary scoop and install several small NACA ducts facing the direction of rotation then drill similar holes on the opposite side as close to the OD of the side cover as possible and install the same NACA ducts facing opposite from the direction of rotation...the ducts close to the OD should create a lower pressure region due to the higher velocity when compared to the ducts close to the ID (same principle as lift for a wing) and the ducts close to the ID should intake the higher pressure air delivered by the fixed scoop on the bike.

So basically just an enhanced version of the set up in the pic above.

If anybody has a Leaf motor they have smoked or an extra set of side plates for a Leaf motor, I'd like to buy them...please send me a message via Endless Sphere and we can work out the details .