Definitive Tests on the Heating and Cooling of Hub Motors

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by DasDouble » Apr 04 2018 5:26am

Has anyone tested yet if a fan mounted on the swingarm, pointing at the hubsinks is accellerating the cooling-down process decisive?
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by SlowCo » Apr 04 2018 7:24am

DasDouble wrote:
Apr 04 2018 5:26am
Has anyone tested yet if a fan mounted on the swingarm, pointing at the hubsinks is accellerating the cooling-down process decisive?
Yes, look at the post from Jestronix a little further down this page:
https://endless-sphere.com/forums/viewt ... start=1925

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by DasDouble » Apr 04 2018 12:48pm

SlowCo wrote:
Apr 04 2018 7:24am
DasDouble wrote:
Apr 04 2018 5:26am
Has anyone tested yet if a fan mounted on the swingarm, pointing at the hubsinks is accellerating the cooling-down process decisive?
Yes, look at the post from Jestronix a little further down this page:
https://endless-sphere.com/forums/viewt ... start=1925
Ah that seems to do a big job. Im gonna have to give this a try. Thanks SlowCo.
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by hillzofvalp » Apr 04 2018 11:08pm

Very good work guys. I have an esk8 motor I call Trillium.. it has sort of dragged on. Perfectionism kills. I'll be sending it to Justin for review... has 6063 rotor and has been extruded.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by justin_le » Apr 05 2018 6:10pm

fechter wrote:
Apr 02 2018 7:30am
One thing I've noticed from actual riding experience is the air speed makes a huge difference in the heat dissipation. If I am climbing a really steep off road trail going about 5-6 mph, the motor will overheat pretty quickly. Using the same power level on the street where the speed is over 15mph, it never overheats.

Somebody (sorry, I forget who) mounted a fan on the swing arm aimed at the side of the motor to increase the air flow. I might give this a try and see how it does with the low speed climbs.
Hey Fechter, it's worth pointing out here that we can answer this quite precisely with the data I've presented rather than doing just a "try and see". I've been going through some pains trying to present all these graphs with numeric axis not just because they look pretty, but to give people the raw info needed to make educated decisions based on the results.

Your line of thought here is a perfect example where we can get a good answer without any testing at all using the info that I published. Referring to this graph here (from https://endless-sphere.com/forums/viewt ... 8#p1368908)
Image
Shell to Ambient Graph Usage.jpg
Shell to Ambient Graph Usage.jpg (55.93 KiB) Viewed 2096 times
You can see that at 5-6 mph, say 9kph, the shell to ambient conductivity is about 5.5 W/degree without hubsinks, and about 8 W/degree with hubsinks. To achieve that same 8 W/degree conductivity without the hubsinks you need a passing aiflow of 18 kph. So if your side fans end up blowing air on the side cover roughly equivalent to a 18kph headwind, then the cooling will be exactly as having no fan but hubsinks installed.

Say your fans blow at more like 30 kph, then the effective conductivity is 12 W/degree. But to determine the total effect, you need to also factor in the core to shell conductivity levels.

From this graph here:
Image
You can see that that the core to shell conductivity with Statorade in this hub is 4.5 W/degree at your 5-6 mph point.

That results in NET conductivities (Knet = 1/(1/K1 + 1/K2)) as follows

5-6 mph, No Hubsinks = 2.48 W/degree
5-6 mph, With Hubsinks = 2.88 W/degree
5-6 mph, with 18kph fan = 2.88 W/degree
5-6 mph, with 30 kph fan = 3.27 W/degree

So it helps a bit, no doubt, but you will get diminishing returns as you put more and more effort into cooling the shell. Even if you had absolutely perfect thermal conductivity from the shell to ambient, you're still limited by the 4.5 W/degree from the core.
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by tolkaNo » Apr 08 2018 5:13am

Whats the deal when it comes to applying statorade and varnish on the magnets?

Do you use statorade first then spray varnish over it or vice versa? Or does it not matter

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by amberwolf » Apr 08 2018 8:26pm

Do you know of a varnish that sticks to liquids?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by tolkaNo » Apr 09 2018 3:52am

amberwolf wrote:
Apr 08 2018 8:26pm
Do you know of a varnish that sticks to liquids?
Don't liquids dry at a certain point?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by SlowCo » Apr 09 2018 4:16am

tolkaNo wrote:
Apr 09 2018 3:52am
amberwolf wrote:
Apr 08 2018 8:26pm
Do you know of a varnish that sticks to liquids?
Don't liquids dry at a certain point?
Google "ferrofluid" (=statorade) or look it up on YouTube. Then try to understand if it would work with varnish covering it.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by tolkaNo » Apr 09 2018 4:26am

SlowCo wrote:
Apr 09 2018 4:16am
tolkaNo wrote:
Apr 09 2018 3:52am
amberwolf wrote:
Apr 08 2018 8:26pm
Do you know of a varnish that sticks to liquids?
Don't liquids dry at a certain point?
Google "ferrofluid" (=statorade) or look it up on YouTube. Then try to understand if it would work with varnish covering it.
It's only supposed to go in between the gaps of the magnets no? The varnish will still cover the other 99% of the magnets because that's not where the fluid is supposed to go was my understanding

Im just asking the question if no-one has the answer its fine :?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by SlowCo » Apr 09 2018 5:49am

tolkaNo wrote:
Apr 09 2018 4:26am
Im just asking the question if no-one has the answer its fine :?
Short answer: if you vent the side covers then first put on the varnish (and let it dry) then add ferrofluid.

If you don't vent the side covers then don't put varnish on the internals of the hub motor as it will act as an heat insulator lowering the effect of the ferrofluid. And be aware that you need Statorade or equivalent ferrofluid that can handle the heat and doesn't dissolve the varnish and the glue of the magnets.

The ferrofluid "bridges" the gap between the stator and the rotor to transfer heat from the stator to the rotor. Ferrofluid acts in a special way around magnets forming spikes that can form that "bridge". So it has to stay fluid to do that. Read more here:
http://www.ebikes.ca/product-info/statorade.html

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by tolkaNo » Apr 09 2018 6:24am

SlowCo wrote:
Apr 09 2018 5:49am
tolkaNo wrote:
Apr 09 2018 4:26am
Im just asking the question if no-one has the answer its fine :?
Short answer: if you vent the side covers then first put on the varnish (and let it dry) then add ferrofluid.

If you don't vent the side covers then don't put varnish on the internals of the hub motor as it will act as an heat insulator lowering the effect of the ferrofluid. And be aware that you need Statorade or equivalent ferrofluid that can handle the heat and doesn't dissolve the varnish and the glue of the magnets.

The ferrofluid "bridges" the gap between the stator and the rotor to transfer heat from the stator to the rotor. Ferrofluid acts in a special way around magnets forming spikes that can form that "bridge". So it has to stay fluid to do that. Read more here:
http://www.ebikes.ca/product-info/statorade.html
I feel like its easier to just not varnish the magnets at all if using ferrofluid then

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by spinningmagnets » Apr 09 2018 6:37am

Most builders who have used a water-proofing motor-varnish have done it to rust-proof the insides when they decided to add vent-holes to the sideplates, which is usually done to let out heat.

Statorade also helps the motor shed heat, but...a small percentage of particles in the dust around everyone is ferrous, so if you had vent holes combined with statorade, there is a fear that ferrous dust-grit would accumulate in the statorade. I don't know of anyone who has added motor varnish to a sealed motor and then added Statorade. If you try this, you would likely be the first to do so.

The fluid in Statorade is oil-based, using an oil with a low vapor-pressure, so...any evaporation would take many years, if at all.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Cowardlyduck » Apr 09 2018 7:05am

spinningmagnets wrote:
Apr 09 2018 6:37am
I don't know of anyone who has added motor varnish to a sealed motor and then added Statorade. If you try this, you would likely be the first to do so.
I actually did this back in June 2016, and I am continuing to experiment doing so.
This was the result of my initial attempts:
https://endless-sphere.com/forums/viewt ... 0#p1198704
Image
Image
Image

I did the same thing on another motor with smaller vent holes and the result that time were much better:
https://endless-sphere.com/forums/viewt ... 0#p1267918
Image
Image
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Doc had some good thoughts on what caused this difference also:
https://endless-sphere.com/forums/viewt ... 5#p1279216

As mentioned in the posts above, my other motor is a Leaf '1500w' I have also vented with FF and heat-sinks. It doesn't seem to be suffering as much as the HS4080 did and I have been continuing to run it with FF, venting and Fans for about another 1000km or so now. So far it still seems to be running fine, so I have no reason to open it back up again as it is a PITA, but when I eventually do, I will try and share the results then. :)
I also have a '1000W Golden motor' which is just vented on one side and has about 5ml of FF. I've not opened it at all since adding the FF and it's done at least 3000km. So far no issues apart from a bit of increased drag when hot.

***EDIT***
Sorry Spinning Magnets, just realised you specified "Sealed" motor....which I even quoted. :lol: I'm sure my experiments are still somewhat relevant however so I'll leave the response as is.

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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by DasDouble » Apr 15 2018 4:56am

Allex wrote:
Oct 30 2017 3:18pm
Meanwhile in Russia, they take another way to cool down the motors.
It seems that ferrofluid is not enough for them so they actually use Active cooling and it is far more complex one.



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Has anyone an idea how I can get my hands on these 3D files? I would like to do that for my QS 205 V3 as well. That would save a lot of time, having these as a template. Thanks
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Allex » Apr 16 2018 4:58am

https://www.youtube.com/watch?v=PpkxWSEWJy0&t=92s

This guys currently builds a setup for a V3
Ask him.

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Re: Current test with 9mL of fluid

Post by justin_le » Apr 26 2018 1:29am

justin_le wrote:
Mar 10 2018 2:26pm
So after wiping off the remaining Statorade inside the motor, I decided to reseal the motor and resume this experiment but using a 9mL quantity of Statorade that would have full conductivity at 400 rpm, rather than being right on the slope of maximum change. As well, I figured that if the stator itself was going to absorb fluid in any cracks and fibers that this particular core would be well saturated by now, so if we did see a decreases in effectiveness with this 9mL fill then it was definitely from some form of evaporation loss.

Anyways, I'm now over 3 weeks into this latest experiment. The raw test data continues to have this form, what you see are daily fluctuations in the temperature of our building
MXUS 9mL, 120oC, Example Data.jpg

But when I do the data analysis for conductivity, we're not seeing ANY change at all so far.
MXUS Evap Test at 120oC, 9mL.jpg

It's been hovering right around 4.75 W/K for the first 24 days. That's 29,000 km. Assuming that it is being lost at the same estimated rate of ~0.3 mL/week, then we probably won't notice any decrease in conductivity until it's down to 7mL or so. That would be at least another month down the road, so we'll keep 'er running and see.
For those following this longevity test, I did several more weeks of this experiment approaching nearly 2 months now, with 9mL of Statorade in a MXUS motor running at 120 oC. Dark blue line is the measured thermal conductivity, light blue is the conductivity reference with no Statorade.
MXUS Evap Test at 120oC, 9mL, Day 56.jpg
MXUS Evap Test at 120oC, 9mL, Day 56.jpg (71.72 KiB) Viewed 1618 times
I'd say that's pretty darn flat. A slight decline perhaps but still a long way from the current 4.8 W/degree down to 2.6 W/degree. Total equivalent distance is over 65,000 km now. That's one and a half loops around the planet.

The experiment has since been stopped since the anderson connector on the motor phase wires melted with the high field weakening current. With just 2 phase wires connected the sensorless controller went a bit berserk and the motor shook itself from the test stand and dislodged the IR sensors and all that. I've needed to use the wind tunnel for other things so I didn't bother setting it back up and am not sure if there is much value in continuing this.
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by liveforphysics » Apr 26 2018 2:04am

The samples with FF that gummed up were perhaps due to varnish/epoxy internal coatings dissolving.

Do we have any examples of it getting gummy over time in motors that are only using stock surface coatings (like I assume your test used?)
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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Cowardlyduck » Apr 26 2018 2:18am

Nice work Justin!
Yeah I can't disprove what Luke said above and it is entirely possible it was down to the coatings I applied in my cases that caused the FF to be consumed over time. I ended up just adding more to one of those motors so it will be interesting to see how that turns out. :lol:

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by eCue » Apr 26 2018 3:15am

Percentages wise its a 85% improvement in heat shedding :shock:

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by mrbill » May 10 2018 9:14am

Hi Folks:

I've got a partial syringe of Type A Statorade purchased in 2016 or earlier and a full syringe I purchased in March 2018 labeled as "Statorade". Can anyone tell me if these formulations are compatible and can be mixed together in the same motor?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by DasDouble » May 10 2018 11:31am

Has someone already tried Sprayon together with 8ml ff?

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by macribs » May 10 2018 1:22pm

Don't know if it was SPRAY ON varnish but there was one report of red varnish that did not work well with statorade. If no one has actually tested that brand I would just skip it to be on the safe side. After all when using statorade your hub will get a thin layer of oil coating inside that might be enough to avoid rust and corrosion? Or if you do have the motor apart rub som gun oil or similar over steel parts inside motor.

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by Offroader » May 27 2018 9:54am

I just wanted to give an update about my 40mm EDF fan in my MXUS 3000 Turbo hub motor. The motor is ducted using silicone to direct outside air through the coils. The side cover of my hub motor has holes drilled into it.

I can say that I've ran it the whole last summer, and am running it this summer without any issues. When the weather is hot outside and around 90F degrees, this is the time I like most to ride my bike and also the most difficult times to deal with motor cooling, I am pushing the MXUS motor hard at 8000KW for a very long time with my large 3 KWH battery. I ride extremely hard with only using full throttle.

The silicone ducting I made directly on the coils and aluminum stator has held up without any issues.

I can adjust the speed of the EDF fan and with the very hot summer days I need to turn it up to 80 watts (this is what the 12 volt power supply draws as read on my Max-E) to be able to drive my bike as hard as I can with any risk of overheating. The great thing is I run this 40mm EDF at these high speeds for my entire 1-2 hour bike rides without any issues. This tiny EDF is very reliable and very powerful also at moving air. When this tiny EDF is using 80 watts it is spinning extremely fast, if you held the fan at arms length away it would feel like sticking your head out of a car window driving on the highway. No computer fan would even come close, these fans are used to fly airplanes at very high speeds.

The noise isn't too bad but it isn't silent. At a speed above 15MPH you won't hear it over the wind noise. You do get used to the noise, just like you would the noise of your car, you just don't notice it. The great thing is I can adjust it by reaching back under my seat, so if I want it silent I just turn the knob and I can do this while riding also.

I'm going to finish my Cromotor wheel build to compare this to FF and hubsinks soon. I want to do a direct comparison to see if its worthwhile to do this kind of fan cooling when a more simpler solution is available.

Here is a link to the 40mm EDF I use:
https://hobbyking.com/en_us/dr-mad-thru ... tt-3s.html

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Re: Definitive Tests on the Heating and Cooling of Hub Motors

Post by eCue » May 27 2018 10:41am

Excellent mod and fan wow. Hub Motor cooling is going to be revolutionized by the looks of it. Looking forward to tests.Off hand Im curious if the added heatsinks slows cooling or increases it. The gap on the rc fan compared to current methods would be most interesting as well

from link - This 40mm, 8-blade combo with the inrunner motor was developed by Dr. Bret Becker, for his record breaking Electrolyte Micro EDF sport jet, and is capable of pushing the model past the 100mph barrier
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