Heat sinks for hub motors?

Eastwood

Eastwood

100 kW
Joined
Jan 13, 2021
Messages
1,479
Hello fellow E-bikers!

So I stumbled across this heat sink kit that I’m sure many of you are familiar with. I would love some feedback whether these kits actually help? In theory this seems like it would lower the heat. Do any of you have experience with these or have you heard any positive feedback?
https://hubsink.com/

Thanks!
 
Yes they do work.

It goes like this

Hubsinks and some sort of heat transferring fluid in hub > Case cover drilled with air holes > Heat transferring fluid alone > Hubsinks alone > A sock soaked in water wrapped around hub > nothing ( bare hub).

From what I have researched. From best to worse.
 
Eastwood said:
Do any of you have experience with these or have you heard any positive feedback?
Click to expand...
Just a little discussion here and there that might be useful:
https://endless-sphere.com/forums/search.php?keywords=hubsink*&terms=all&author=&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search
 
Actually, there are a few more you can add to your list, all valid except the last and the drip/spray.

DIP THE HUB MOTOR INTO A RIVER, POND, FOUNTAIN - This would fall under your sock idea. I did this once on a very hot day and at the bottom of a long steep hill after touching the hub I let the front hub sit in a river.

POUR YOUR DRINKING WATER ON THE HUB - You can probably extend this idea to riding with a bottle that will constantly drip or spray h20 onto hub.

GET A BIGGER MASS MOTOR like say go from a small geared 500 watter to a direct drive 3kw

go from steel stator to aluminum stator

Wasn't there a few people that tried mini fans on the case and in the hub.


DogDipstick said:
Yes they do work.

It goes like this

Hubsinks and some sort of heat transferring fluid in hub > Case cover drilled with air holes > Heat transferring fluid alone > Hubsinks alone > A sock soaked in water wrapped around hub > nothing ( bare hub).

From what I have researched. From best to worse.
Click to expand...
 
markz said:
POUR YOUR DRINKING WATER ON THE HUB - You can probably extend this idea to riding with a bottle that will constantly drip or spray h20 onto hub..


DogDipstick said:
.
Click to expand...
Click to expand...

That’s such a simple and great idea to just simply pour drinking water on it. You could even freeze a couple of water bottles.
 
DogDipstick said:
Yes they do work.

It goes like this

Hubsinks and some sort of heat transferring fluid in hub > Case cover drilled with air holes > Heat transferring fluid alone > Hubsinks alone > A sock soaked in water wrapped around hub > nothing ( bare hub).

From what I have researched. From best to worse.
Click to expand...

What type of fluid do people put inside the hub motor??
I’ve seen it where people drill holes but I would be worried if I got caught in the rain. Plus all the road debris like sand and grit etc.
 
Eastwood said:
Sounds like I’ll probably go with the heat sinks for cooling. Is there any place you can buy some anodized red ones or other color options?
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Hub sinks won’t do much, or anything, if you don’t add fluid to transfer the heat from the stator to the hub body. Climb a hill, feel your motor at the top. Add Statorade, climb the same hill, and the motor will feel hotter, since there’s now a path for the heat to travel across. You might not need the hub sinks after adding the fluid, since you’ll be able to see (feel) if the motor is getting hot, since you can’t right now.

PS. If you're doing it for the looks, then you could even paint them, but maybe add wiring for LEDs too.
 
E-HP said:
Hub sinks won’t do much, or anything, if you don’t add fluid
PS. If you're doing it for the looks, then you could even paint them, but maybe add wiring for LEDs too.
Click to expand...

OK this is the first I’m hearing of this Statorade. That being said I would think the heat sinks along with dissipate a lot of heat because there’s definitely a lot of heat buildup on the hub casing where the sinks mount too.

I guess one could use engine paint if you wanted to change the color of the sinks. Would much prefer anodize though. Probably just leave it black if that’s all they come in
 
Eastwood said:
OK this is the first I’m hearing of this Statorade. That being said I would think the heat sinks along with dissipate a lot of heat because there’s definitely a lot of heat buildup on the hub casing where the sinks mount too.

I guess one could use engine paint if you wanted to change the color of the sinks. Would much prefer anodize though. Probably just leave it black if that’s all they come in
Click to expand...

Don't know how you missed it. If you clicked on the link that amberwolf provided, it's mentioned in several posts on the first page of results.

Virtually all of them that don't mention statorade, mention ferrofluid, which is statorade is one formulation of.

No need for engine paint. If your hub sinks get hot enough to damage paint, then it's long after your motor has fried itself. I take it you're not trying to keep things stealthy.
 
Ferro Fluid (FF)

Automatic Transmission Fluid but it tends to leak more unlike FF, even if you high heat RTV sealant the covers for ATF.
 
E-HP said:
Eastwood said:
Don't know how you missed it. If you clicked on the link that amberwolf provided, it's mentioned in several posts on the first page of results.
Click to expand...

Yeah I didn’t miss it, I clicked on the link. I was meaning that this is the first day I’m hearing of fluids being put in the hub because I am new to eBike building.

E-HP said:
No need for engine paint. If your hub sinks get hot enough to damage paint, then it's long after your motor has fried itself. I take it you're not trying to keep things stealthy.
Click to expand...

Yeah I wouldn’t consider painting the heat sinks was just suggestion if one wanted to paint, Engine paint would be the best because most paint would chip very quickly without overheating just the normal heat.
As far as my bike being stealthy I guess that depends on your perception of what stealthy is. I think Enduro frame E bikes look like motorcycles but yet they’re called stealth LOL
Click to expand...
 
Eastwood said:
As far as my bike being stealthy I guess that depends on your perception of what stealthy is. I think Enduro frame E bikes look like motorcycles but yet they’re called stealth LOL
Click to expand...

That is because people take brand names and genericize them (like kleenex, clorox, etc.). Stealth Bikes (in australia) first created that kind of ebike, with the Bomber and the Fighter models, named after the planes...stealth bomber, stealth fighter, because it sounds cool, not because it has anything to do with stealthiness. ;)

Then there are bikes people call stealth because they are actually trying to be stealthy with it, by hiding all the electrics in a way that make it look like a plain pedal bike. Those would be completely different. ;)
 
Eastwood said:
That being said I would think the heat sinks along with dissipate a lot of heat because there’s definitely a lot of heat buildup on the hub casing where the sinks mount too.
Click to expand...
Sure. They'll make the hub casing cooler. But they wont' make the *motor* cooler (not enough to make much of a difference, anyway, at heat levels that are requiring heatsinks to start with), until you create a heat path for the motor heat to reach the casing better than the air that's in there right now. Air is a GREAT insulator.

If you want to know more about how that works, Justin_LE has a thread about Definitive testing of Heating and Cooling of Hubmotors, or something along those lines, with actual lab experiments and test data, along with explanations of waht's going on in there.


If you want the heatsinks some other color, you can always polish the existing color off of them, then re-anodize them in whatever color you want. But they are black (like most heatsinks) because black radiates the heat better.
 
amberwolf said:
Sure. They'll make the hub casing cooler. But they wont' make the *motor* cooler (not enough to make much of a difference, anyway, at heat levels that are requiring heatsinks to start with), until you create a heat path for the motor heat to reach the casing better than the air that's in there right now. Air is a GREAT insulator.

If you want to know more about how that works, Justin_LE has a thread about Definitive testing of Heating and Cooling of Hubmotors, or something along those lines, with actual lab experiments and test data, along with explanations of waht's going on in there.
Click to expand...

OK thanks, I’ll look that thread up!
And yeah that makes perfect sense of creating a pathway for the heat to get to the heat sinks. I can see how that would be much more efficient.
 
Just get a bigger motor that can handle more power, thats if you can go bigger.

The 5kw mxus requires 150mm dropout widths, the 3kw mxus you can fit in a normal 135mm dropout width.

Another unique way to run cooler might be to look into going 2wd ebike, but its always better to go one bigger motor.
 
markz said:
Just get a bigger motor that can handle more power, thats if you can go bigger.

The 5kw mxus requires 150mm dropout widths, the 3kw mxus you can fit in a normal 135mm dropout width.

Another unique way to run cooler might be to look into going 2wd ebike, but its always better to go one bigger motor.
Click to expand...

I hate ( no offense ) these options.

Going for performance is not adding weight. I love my little hub motor, and own a big hub motor too. Little guy is great, being higher power to weight ratio with ATF, anaerobic gasket maker, and hub sinks it can easily run what a bare 3Kw motor can run contin. More, even, and retain the great power to weight ration and weight distribution near 50%F/50%R on the bike.

I bet I could do 6kw contin with the lil motor I got cooled the way I do. It gets 4kw now, on a 1kw motor... and half the weight ( feels like ) than a 3Kw hub of the same manufacture....

The 3Kw motor is friggin hefty. The 1kw motor + coooling has better pwoer to weigh ratio at this power level.

Only reasn you ( I) want a big hub is to ... fill that with sealant and oil, and sink about 20kw...

But i honestly thinking that the 1kw motor, oil cooled, heat sunk, might be better than a 3Kw heavyheavyhippo on stock form uncooled.

Still its the same debate (arguments) as good lightweight MTB high quality wheels vs heavy crude MOTO rims.... in bicycle applications.
 
If you're content with a drooling mess of a bike, there are lots of stinking gas-burning motorcycles that are far more refined and powerful.

Among the greatest benefits of electric traction power are its simplicity, low maintenance, and cleanliness. I'll carry a bigger motor than absolutely necessary to get those things. Definitely won't give them up to save a handful of pounds.
 
Chalo said:
If you're content with a drooling mess of a bike, there are lots of stinking gas-burning motorcycles that are far more refined and powerful.

Among the greatest benefits of electric traction power are its simplicity, low maintenance, and cleanliness. I'll carry a bigger motor than absolutely necessary to get those things. Definitely won't give them up to save a handful of pounds.
Click to expand...

I think there's clearly a trade-off between the big motor and hot rodded small motor, so it comes down to a decision based on preference and needs. It's pretty fun riding around with a small 1kW motor fed plenty of current and voltage. I know I'm trading off efficiency and power for lighter weight and nimbleness. I know I'd have more power to the ground and go farther with a bigger motor using the same watts, since more is going to the wheel instead of heat, and that no matter how I control the excess heat of a small motor, it won't recapture the lost watts. Of course, if I "needed" that extra power, I'd get the big motor :D

The extra torque is attractive, no doubt:
https://ebikes.ca/tools/simulator.html?motor=MGRIN2706_SA&batt=B7223_AC&cont=cust_70_200_0.03_V&hp=0&axis=mph&cont_b=cust_70_200_0.03_V&motor_b=MX4506_Ferro&batt_b=B7223_AC&hp_b=0&bopen=true&kv_b=8.73&kv=10
 
Thanks for all the input guys! I would rather hot rod a small motor to have the lighter weight. My motor is not overheating so there’s no reason to buy a bigger motor. I started this topic not because I have heat issues, I was simply looking for suggestions whether these heat sinks are efficient. Maybe I mentioned above I’m new to building E bikes so all this is new to me. I will go with the Statorade Ferrofluid and the heat sinks. Also I’ve ordered a 72V battery and I want to be prepared for any extra heat.
Thanks for all the suggestion E-bikers! :D
 
Back when I was running the wrong motor, I poured water on my hub every day, and used the wet rag on it so the water did not simply run off it so fast.

this problem was cured not by getting a huge motor, but by getting a slightly bigger motor. I went from an Aotema, which had a slightly high rpm for use with 26" wheel, to a 9 continent with a "normal" rpm motor. I stopped having any difficulty with overheating, until I began to run 3000w through it. Even at 3000w, I got 1000 wh through it before I had to stop, and did not want to carry much more than that anyway.

Any discussion of needing heat sink or not, begins with actually knowing the temp inside the hub. Measuring temps outside the hub, like at the axle stub, 200F is ok, but above that you are likely to be toasting your windings, and hall sensors.
 
Chalo said:
If you're content with a drooling mess of a bike, there are lots of stinking gas-burning motorcycles that are far more refined and powerful.

Among the gr
Click to expand...

Lol not a drop leaked in over a year of hard use. Lol.


It's not saving a few lbs... It is doubling the power to weight ratio or greater.

Lol worries about leaking oil. Lol x2. My bike don't "drool" at all. I suppose it might if you used some junk like RTV... That what you did? Stator aid is terribly expensive. Lol. For small gains. A quart
of atf is 4$.
 
DogDipstick said:
It's not saving a few lbs... It is doubling the power to weight ratio or greater.
Click to expand...

Of the motor, maybe. What's the percentage difference in system weight including the rest of the bike and you?

I have a bike with a ~14 pound front hub, and one with a ~22 pound front hub, both running on the same amount of electrical power. They ride differently, because the bikes are quite different. It's hard to notice anything I could attribute to the weight disparity between the motors, though.

Lol worries about leaking oil. Lol x2. My bike don't "drool" at all. I suppose it might if you used some junk like RTV... That what you did?
Click to expand...

I would no more consider filling a bicycle hub motor with oil than I'd consider filling a cordless drill with hot sauce. Electric motors are mature tech, and they're everywhere. Approximately zero of them use any kind of liquid cooling. In industry, those rare motors that do use liquid cooling, don't do it by filling air spaces with oil. So either all the engineers in the world are doing it wrong, or you're doing it wrong, or you have an edge case that nobody else has bothered to design for. Personally, I doubt it's option one.
 
Chalo said:
So either all the engineers in the world are doing it wrong, or you're doing it wrong, or you have an edge case that nobody else has bothered to design for. Personally, I doubt it's option one.
Click to expand...

They certainly do. Lol.

i did consult with my engineer. You edgy one you. We see em all the time in our industry.. of engineering.

You, however, could just google to see that.

https://www.google.com/search?safe=off&client=firefox-b-1-d&sxsrf=ALeKk01YLk_JcbMPi555SfwuL_Hl4YUJBw%3A1611510431155&ei=n7INYPmLCbGWwbkP7OSe8Aw&q=oil+cooled+electric+motor&oq=oil+cooled+motor&gs_lcp=CgZwc3ktYWIQARgAMgQIABBHMgQIABBHMgQIABBHMgQIABBHMgQIABBHMgQIABBHMgQIABBHMgQIABBHUABYAGDJYWgAcAJ4AIABAIgBAJIBAJgBAKoBB2d3cy13aXrIAQjAAQE&sclient=psy-ab

https://www.combimac.com/oil-cooled-electric-motors.html

https://www.hpevs.com/hpevs-ac-electric-motors-oil-cooled-for-marine-use.htm

https://www.burgiengineers.com/products/high-performance-liquid-cooled-ac-motors

Chalo, you are wrong. And or probably not an engineer.

Personally... I doubt it is not both.
 
Another unique way to run cooler might be to look into going 2wd ebike, but its always better to go one bigger motor.

Bigger isnt always better my friend with 5k 3.5t qs motor with a 3k controller and some 60+ah battery pack ( there were some 350 cells used to make his pack I really haven't done it justice) and he could never understand how my cheap ass 2x 1000w hubmotors 1800w controllers and a cheap ass pair of 60v 12ah batteries could keep up
 
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