Definitive Tests on the Heating and Cooling of Hub Motors

[fechter]

I have looked through this post but maybe I missed, it, I have seen where FF is softening or acting as a solvent on the coatings of the copper windings inside motors, but I didn't catch if there was a list anywhere of specific types reacting to specific motors, so as in my case, is there a "safe" form of FF that has shown to not react with the coatings inside a V2 Cro Motor?

I'm very interested in trying this out, just a bit nervous about potentially damaging a $600 motor.

It's in there somewhere. It was some kind of spray paint that was on the windings that got mushy. Not the factory materials. Most of the FF should be trapped on the surface of the magnets, so not much should be getting on the windings anyway, but I wouldn't worry much about the enamel on the copper or the glue holding the magnets (though we don't really know what might happen long term).

I do know ester-based oil is used in the air conditioning systems of hybrid and electric cars because it is electrically non-conductive and won't cause leakage current if it leaks into the compressor motor (electric). It is compatible with the motor materials in those systems.

I'm thinking of ways to make fins for my A2B motor. Since the nice ones sketchism made most likely won't fit my motor. One idea I had was to make a bunch of fin sections of two fins each (slice of U channel), drill a small hole through the fins near the base, and sting them together with a piece of stainless aircraft cable. Spacers between the sections would even out the fin spacing. This would wrap around the hub like a chain and fit a wide range of diameters. Easy to fit through the spokes too. Each fin section could be slightly curved on the base to come close to the hub radius. If the sections are narrow enough, they can just be flat. Paste or glue would fill in the gap for heat transfer. The cable could be tensioned with something resembling a turnbuckle on the ends (this is probably the trickiest part).

 

[LI-ghtcycle]

I have looked through this post but maybe I missed, it, I have seen where FF is softening or acting as a solvent on the coatings of the copper windings inside motors, but I didn't catch if there was a list anywhere of specific types reacting to specific motors, so as in my case, is there a "safe" form of FF that has shown to not react with the coatings inside a V2 Cro Motor?

I'm very interested in trying this out, just a bit nervous about potentially damaging a $600 motor.

It's in there somewhere. It was some kind of spray paint that was on the windings that got mushy. Not the factory materials. Most of the FF should be trapped on the surface of the magnets, so not much should be getting on the windings anyway, but I wouldn't worry much about the enamel on the copper or the glue holding the magnets (though we don't really know what might happen long term).

I do know ester-based oil is used in the air conditioning systems of hybrid and electric cars because it is electrically non-conductive and won't cause leakage current if it leaks into the compressor motor (electric). It is compatible with the motor materials in those systems.

I'm thinking of ways to make fins for my A2B motor. Since the nice ones sketchism made most likely won't fit my motor. One idea I had was to make a bunch of fin sections of two fins each (slice of U channel), drill a small hole through the fins near the base, and sting them together with a piece of stainless aircraft cable. Spacers between the sections would even out the fin spacing. This would wrap around the hub like a chain and fit a wide range of diameters. Easy to fit through the spokes too. Each fin section could be slightly curved on the base to come close to the hub radius. If the sections are narrow enough, they can just be flat. Paste or glue would fill in the gap for heat transfer. The cable could be tensioned with something resembling a turnbuckle on the ends (this is probably the trickiest part).

Sounds like a good idea!

The other idea would possibly just using a cable ferrule once you have it tensioned.

I haven't used such a system, but there must be some form of tool that tightens the cable so you can then swage the ferrule.

 

[Cowardlyduck]

Lol - I guess I should chime in now. :lol:

eTrike most of what you say is correct, but a few things are not.
There's no rust in my motor...I think you are probably just seeing some of the FF mixed with the varnish.

Thisis the varnish I used:

You right that nothings been answered definitively, but that doesn't discount my findings...I think what I found just shows more investigation is needed. I may or may not find the time to do that myself...others are more than welcome to have a go at it also if you have the time.

I also don't think it's been proven either way that venting does/doesn't work with FF. I might make some logical sense that it won't work, however I'm still on the fence till it's proven one way or the other. What I've done so far is not proof.

Cheers

 

[Cowardlyduck]

Cheers Cd, you're the perfect one to ask. Agree on points above and meant no disregard to your results whatsoever, merely that the stuff only seemed affected where it could grind the varnish into its mix. You motor surely wasn't rusty but I'd expect the FF to have turned a bit so along with the mix of varnish and debris. How easily can you remove the remaining varnish by hand or does it feel softened?

Not sure how the FF would cause rust...oil doesn't usually do that.
Every time I open my motors I give them a wipe over with baby wipes. That motor is sealed back up and on my bike now so I'm not going to open it up again any time soon.
From memory, even a firm rub with the wet wipes would not remove the varnish from the windings, but it did from the magnets.
I think what you say about the smooth magnets not providing a good sticking surface is true and likely part of the reason why the FF caused it to come off there rather than the windings.

Overall though, if your adding FF or oil to a motor I don't think you really need a varnish anyway. I only add the varnish to my motors cause they were vented, so for most people I think it's a moot point, assuming the FF doesn't react with the other coatings and glues found in a stock motor though.

Cheers

 

[Cowardlyduck]

Thanks for the extra bit-- I assumed your cleaned photo was post baby wipes or were you able to scrub the rest of the varnish off as well?

Yeah, I just wiped off what would come off without too much effort. I only cared about seeing how it had performed and getting it up and running again and making it so it would last. No scrubbing what-so-ever.

I was referring to this pic for looking rusty but I can see some faint black in there too. Did you notice any difference in temps?:

Yeah, not rust, just FF mixed with varnish and probably some dirt/dust also. I did notice about 10-15C lower temps initially, but that didn't last long. I realise now why, as it would have reduced down with the reaction with the varnish.

I also did the same to my '1500W' Leaf motor. Same varnish + FF and vented, but I haven't used it nearly as much as the HS4080 posted about above. I'm yet to open the Leaf and don't really want to unless I have to, so I'm thinking about just adding more FF to compensate any absorption/reduction from this same reaction....no idea if that's a bad idea or not though. :lol:

Cheers

 

[Offroader]

I can never understand why you guys spray that varnish on the stator and magnets. It just insulates everything, and doesn't really do anything. Always seems to cause problems down the road and makes repair process more difficult.

 

[spinningmagnets]

Maybe some people should get a grinder / dremel out and chop off some for personalised aesthetics

This is one point of discussion where I agree with John. We do NOT have three vendors to choose from. Chew on that for a few seconds. If there is only one guy selling these (and fortunately for us, the majority of hot rod DD hubmotors have the same diameter shell), then...he should sell LONG fins, and the customer can get off his lazy ass and cut them to the length that they desire. (I own an angle grinder with an abrasive cutting wheel, and also a Dremel with a cutting wheel...and yes... I have a LOT of scars).

 

[John Bozi]

SM I'm flattered.

I think people also need to be reminded that designing / fabricating custom closer to cost price parts means massive quantities and financial out lay and time in design and then running to the post office. I am not Sketch nor am I his spokesperson, but from experience, it's not a business and life choice career goal. He followed through with something that he believed in enough for himself, his mates and the community that he gained the knowledge to build on, and manufacturing on a large scale was the only way to make it price effective.

You can't just keep redesigning another 6000 parts (not literal, I have no idea how many) when the tools have been set and the bulk cash has been paid.

You won't get many people coming along sticking out their necks. But I may be wrong, China might suddenly start selling the same fins...

Anyways I think I'm preaching to the converted....

Fintastic.

 

[drew12345]

Maybe some people should get a grinder / dremel out and chop off some for personalised aesthetics

This is one point of discussion where I agree with John. We do NOT have three vendors to choose from. Chew on that for a few seconds. If there is only one guy selling these (and fortunately for us, the majority of hot rod DD hubmotors have the same diameter shell), then...he should sell LONG fins, and the customer can get off his lazy ass and cut them to the length that they desire. (I own an angle grinder with an abrasive cutting wheel, and also a Dremel with a cutting wheel...and yes... I have a LOT of scars).

K, it's up to sketch. Several people were interested and so was I. If no big deal and sketch wants to do it, then let him. If he doesn't, no big deal. I already ordered the long ones. If it was not an issue to order the shorter ones, then doesn't hurt to ask, right? Just say it's not a good idea. No need to make a big deal about it.

 

[macribs]

I would like to try epoxy next time motor is open. I did varnish as well to avoid rust and it is a must as I live on the coast with salty winds and weather coming in from the sea. It never occurred to me it could be a problem with FF. So next time I will try some thin layer of epoxy to prevent rust, guess that is a winter project.

 

[sketchism]

I really look forward to see people starting to take those small motors all the way up to saturation point with the use of FF and heatsinks.
How much peak power and torque can those small and tiny dd hub motors make before saturation sets in? And will this heat sink and FF combo change the way we look at powerful hubmotors?

i'm away from home for a little while but this has actually been one of my priorities personally,

I would REALLY like to get above 6-8Kw+ with a thin hub on my off road Norco DH build which ill be testing when i get back home, at the moment i have a MXUS and a QS because 'bigger is better' was the status quo when it came to handling power and delaying saturation, but the drawbacks in unsprung weight and rotational mass are evident mostly in off road and racing, jumps etc, so a lighter 28 or 30mm stator which can handle the same power input as a stock QS, MXUS, Cro, Crown at dramatically less weight would be an even bigger step forward for me on my off road bikes than just going from 10 to 20kw in a heavy hub(which is fun too haha).

I'm thinking of ways to make fins for my A2B motor. Since the nice ones sketchism made most likely won't fit my motor. One idea I had was to make a bunch of fin sections of two fins each (slice of U channel), drill a small hole through the fins near the base, and sting them together with a piece of stainless aircraft cable. Spacers between the sections would even out the fin spacing. This would wrap around the hub like a chain and fit a wide range of diameters. Easy to fit through the spokes too. Each fin section could be slightly curved on the base to come close to the hub radius. If the sections are narrow enough, they can just be flat. Paste or glue would fill in the gap for heat transfer. The cable could be tensioned with something resembling a turnbuckle on the ends (this is probably the trickiest part).

During testing i made a prototype set that was actually just glued directly to the magnet ring with a strong thermal epoxy , this lasted at least 1000Km including heavy offroad climbs etc and i had to break it off with a hammer and chizel when i changed to the HubSink Betas, if you can get the fins to fit the arc of the ring you could do away with the mechanical fixing method and just use the good epoxy http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

or a good metal zip tie or large OD hose clamp would do the job pretty easily too as long as you have a good thermal bridge, tape, paste, glue etc between the sink and hub
https://www.wirecare.com/product.asp?pn=WC04552045&gclid=Cj0KEQjw0_O-BRCfjsCw25CYzYoBEiQAqO9BDJXrW0GPHCOMxDIPjth-GXPT-WNiLyX8_sjphcxGOIMaAmlo8P8HAQ

 

[Offroader]

I can never understand why you guys spray that varnish on the stator and magnets. It just insulates everything, and doesn't really do anything. Always seems to cause problems down the road and makes repair process more difficult.

If we don't in the PNW, this happens over time: https://endless-sphere.com/forums/viewtopic.php?f=30&t=34135
Inland we can run motors for months without corrosion signs that will appear within a week on the coast but we still deal with wetness from the heavens 9 months out of the year inland and get quite a lot of business from coastal dwellers. Fair-weather bikers who store inside needn't worry but if we let a little thing like rain or a dry place to park stop us, we'd hardly ride any bikes. :lol:
I've never had occasion to repair anything after this was done but typical hall/wire repair would still be pretty easy. Prior to repair it is common enough to see hall leads shorted via rusted lams. Other less likely scenarios are more troublesome to deal with so the labor expense of repair usually results in a customer purchasing a new motor.

Thanks for the post, I see why you would want to use varnish, LOL. I just don't ride my bike in the rain, or in the winter if it is wet out. I learned my lesson a long time ago when salt mixed with melting snow got sprayed up onto my bike and temporarily shorted my halls and later shorted my throttle to maximum and I got thrown across my garage.

 

[fechter]

During testing i made a prototype set that was actually just glued directly to the magnet ring with a strong thermal epoxy , this lasted at least 1000Km including heavy offroad climbs etc and i had to break it off with a hammer and chizel when i changed to the HubSink Betas, if you can get the fins to fit the arc of the ring you could do away with the mechanical fixing method and just use the good epoxy http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

or a good metal zip tie or large OD hose clamp would do the job pretty easily too as long as you have a good thermal bridge, tape, paste, glue etc between the sink and hub

I might try that. With a A2B motor, it's a total pain to take the motor apart anyway so having to chisel off heat sinks is not a big deal. Motor heating is my limiting factor now when doing the long, slow hill climbs.

 

[Cowardlyduck]

During testing i made a prototype set that was actually just glued directly to the magnet ring with a strong thermal epoxy , this lasted at least 1000Km including heavy offroad climbs etc and i had to break it off with a hammer and chizel when i changed to the HubSink Betas, if you can get the fins to fit the arc of the ring you could do away with the mechanical fixing method and just use the good epoxy http://www.arcticsilver.com/arctic_silver_thermal_adhesive.htm

or a good metal zip tie or large OD hose clamp would do the job pretty easily too as long as you have a good thermal bridge, tape, paste, glue etc between the sink and hub

I might try that. With a A2B motor, it's a total pain to take the motor apart anyway so having to chisel off heat sinks is not a big deal. Motor heating is my limiting factor now when doing the long, slow hill climbs.

I did that on my Leaf motor (as well as my HS4080):
https://endless-sphere.com/forums/viewtopic.php?f=2&t=48753&start=1275#p1204704

Cheers

 

[macribs]

I'm thinking of ways to make fins for my A2B motor

What diameter is the motor for your A2B?

 

[macribs]

A different take on heat sink for hub motor: johammer electric motorcycle

 

[fechter]

A2B motor measures 208 mm where the fins would go.

 

[Cowardlyduck]

So I finally got around to opening up my little "200W" geared motor to see what went wrong.

Turns out my suspicions were correct and this motor is toast:

So, while 750W is fine...it's not if you have a rubbing hub brake generating extra heat.

Details in my other thread:
https://endless-sphere.com/forums/viewtopic.php?f=3&t=53322&p=1224023#p1224023

Cheers

 

[bigbore]

Late to the party here but would a 10ml FF do better cooling compared to 5ml in a DD 35mm stator motor? Right now I have 5 and thinking to put more.

6-7ml was the sweet spot for it.
more had some % better cooling. but startet with more drag and suffering a bit efficiency

i think it depends on the motor bceaucse not all motor/stator combinations had the same gap from stator to magnets.

i started with 7ml and ended with all 10ml of statorade in it.(205 Motor)
works fine so far. a check after 1000km show me that the fluid stay in place and does not look "vaporized".

I have the same QS205 motor and I've been using 5ml of statorade from some months and I would like to know which advantages there are increasing the amount of fluid.
Now I have this limit: at about 9 kW I reach 100 °C to the motor in less than 4km of flat road. Could I improve the situation by adding more fluid?

 

[sketchism]

Late to the party here but would a 10ml FF do better cooling compared to 5ml in a DD 35mm stator motor? Right now I have 5 and thinking to put more.

6-7ml was the sweet spot for it.
more had some % better cooling. but startet with more drag and suffering a bit efficiency

i think it depends on the motor bceaucse not all motor/stator combinations had the same gap from stator to magnets.

i started with 7ml and ended with all 10ml of statorade in it.(205 Motor)
works fine so far. a check after 1000km show me that the fluid stay in place and does not look "vaporized".

I have the same QS205 motor and I've been using 5ml of statorade from some months and I would like to know which advantages there are increasing the amount of fluid.
Now I have this limit: at about 9 kW I reach 100 °C to the motor in less than 4km of flat road. Could I improve the situation by adding more fluid?

I don't think 5ml is enough for the wide 205, you will see a difference at 7-10 for sure but that does sound too hot still

If you want to measure your resistance, freewheel to full throttle with the bike on a stand and time how long it takes to slow to a stop once you release the throttle, before and after you add the extra FF, i found in real life 7ml was unnoticeable and 10ml was still worth the additional performance, giving your hub a way to shed the extra heat it's absorbed from your stator is the key as well, with 10ml of FF and some cooling i don't think you'll get close to that 100C if that 4km is flat.

 

[Rix]

Late to the party here but would a 10ml FF do better cooling compared to 5ml in a DD 35mm stator motor? Right now I have 5 and thinking to put more.]

6-7ml was the sweet spot for it.
more had some % better cooling. but startet with more drag and suffering a bit efficiency

i think it depends on the motor bceaucse not all motor/stator combinations had the same gap from stator to magnets.

i started with 7ml and ended with all 10ml of statorade in it.(205 Motor)
works fine so far. a check after 1000km show me that the fluid stay in place and does not look "vaporized".[/

I have the same QS205 motor and I've been using 5ml of statorade from some months and I would like to know which advantages there are increasing the amount of fluid.
Now I have this limit: at about 9 kW I reach 100 °C to the motor in less than 4km of flat road. Could I improve the situation by adding more fluid?

Something doesn't sound right and I think its your controller settings aren't dialed as good as they could be for the QS205. I am running about 8kw peak right now through my smaller MXUS 4t V2, and it takes me about 13 minutes or 8.5 miles to get up to 200F on flat road WOT. In fact, even when I had Phase at 370amps and DC @ 120, I wouldn't get to 200F for at least 5- 6 miles of WOT. Even though I have never ran the qs205, being that its a bigger heavier motor, I would think it would take longer and be less prone to heating up faster than the MXUS with same peak KW input.

 

[John Bozi]

I agree with Rix,

but even flat 4km would depend on both average speeds / turn count and regen usage. In start stop traffic where you accelerate hard and then regen hard etc. never winding out to full speed.

still odd....

Another note:
I hope this isn't to obvious but some people might get the wrong impressions from some direction of ideas here especially newer users.
I finally have stated pushing my 1kw a bit harder more often (3.5+kw), and the fins are for sure radiating happily. It's cooling quicker, so I can do it again quicker. Thing is though for those thinking to buy small motors and then running them at higher power levels: there is only so much power you can expect to make a difference.

People can enjoy experimenting as they will, doing this, but I've run like this a long time knowing full well that there is a true waste point.

I can grab WOT or I can gradually open the throttle as I get up to speed. I accelerate the same. I waste power / gain heat differently. The sinks aren't going to give you a higher torque ability in the instant. They are going to let use the torque your motor can deliver / copper etc. longer and more often though.

My recommendation is to get the motor size that suits the amount of power you want to the ground. Upping voltage high speed is a different story.

His a little rainbow to expain.... I have thickened the phase wires up to the axle... had to becareful not to cut the halls instead lol

[youtube]UleCjzaxkZ8[/youtube]

 

[eyebyesickle]

I hope this isn't to obvious but some people might get the wrong impressions from some direction of ideas here especially newer users.
I finally have stated pushing my 1kw a bit harder more often (3.5+kw), and the fins are for sure radiating happily. It's cooling quicker, so I can do it again quicker. Thing is though for those thinking to buy small motors and then running them at higher power levels: there is only so much power you can expect to make a difference.

People can enjoy experimenting as they will, doing this, but I've run like this a long time knowing full well that there is a true waste point.

I can grab WOT or I can gradually open the throttle as I get up to speed. I accelerate the same. I waste power / gain heat differently. The sinks aren't going to give you a higher torque ability in the instant. They are going to let use the torque your motor can deliver / copper etc. longer and more often though.

My recommendation is to get the motor size that suits the amount of power you want to the ground. Upping voltage high speed is a different story.

I am very stubborn, and was planning to do some of my own testing over the next few months anyway. I have some motors coming with high temp copper/magnets, so hopefully they last a little bit longer for me while in testing, although I don't feel like I would really be testing them if I didn't fry at least one!

The thing is, for people on the city commute etc, where the legal limit is 750w, a well as the MPH being regulated, I think there is a lot to gain, even from minimal running differences in temps/watts. If we can downsize the 'standard street legal' hub one size, this would make a major difference. To reiterate, I am looking into:

- Experimenting with various cooling techniques to run the smallest hub I can @ 750w
- Comparing the weight and size difference to the 'next size up street legal standard hubs' that normally run @ 750w
- Calculating the difference in cost ~ materials/shipping compared to the 'next size up street legal standard hubs' that normally run @ 750w
- Goal of saving even a little on weight/cost while still able to reach the legal limit for watts/speed

I think this could make the difference in affordability/availability and also other handling issues etc, (from the hub weight) that hold a few people back. If the 'legal' hubs can be 'improved' upon (not talking about spending more on a high quality 500-750w geared hub, which defeats the purpose) then I think e-bikes in general could become way more popular. I have been talking to local bike shops, and they would be much more open minded to a lower weight/less costly solution for people. Especially if they are just getting in tiny unlaced hubs/kits, and offering to lace them for customers conversions etc...

My line of reasoning, is two-fold. For one, I want, for MYSELF - a smaller/lower weight hub, that I can still max out the legal limits on, no matter if the difference is small, I will get the hard numbers soon enough to evaluate the worth. Second, more affordable/easy availability = increased market/popularity = better for everyone (mostly) in the LEV world.

Perhaps I will just have to waste some time and money going for this, but I believe in it, so here I go! We'll see when I get to some real-world testing. I will be taking this very seriously (for the type of testing I am doing), running the same routes, with the same bikes, one control, one 'modified' etc etc... We'll see what the numbers say... Maybe I will eat my own words/time/money - but there are no claims here, this is only something I am going for. I am still convinced this will be a very good thing. Especially from what I have already seen, both on here, and in person...

To be continued...

 

[Cowardlyduck]

Hey eyebyesickle, I think you might be onto something as I already showed, it is possible to run a puny 200W geard hub at 750W....just not if you have a rubbing brake!

If your keen to push the boundaries, try grabbing some Cute 100 motor's, throwing oil and heatsinks on them and see what they can take reliably.

Cheers

 

[eyebyesickle]

Hey eyebyesickle, I think you might be onto something as I already showed, it is possible to run a puny 200W geard hub at 750W....just not if you have a rubbing brake!

If your keen to push the boundaries, try grabbing some Cute 100 motor's, throwing oil and heatsinks on them and see what they can take reliably.

Cheers

Thanks - first on the agenda are some mini gearless hubs, and we will see if I can get anything worthwhile out of them. 48v@15a or 36v@20a nominal is what I would be looking for approx... These things are so low torque though...

I already have some high temp copper/magnet geared hubs around, but am really hoping I can do something with the gearless, because I am not confident that I would be able to keep the oil sealed up... and I don't see bringing something better to fruition for the masses, at least not anything with oil, anytime very soon. Although you had better believe, I will have one for myself =) and tinker until I get the oil situation as much under control as I can. I actually have NOT experimented with adding oil to a hub yet, so we will have to see what happens...

I'll talk more when I have something to show... Maybe I can keep my mouth shut until then :lol: