I have found a way to easily and succesfully cool hub motors

[ebikedelight]

I ordered 8 aluminum heat sinks with heat dissipation fins - the heat sinks are 6" long .

I first attached them directly to the face of each side of the hub motor using a small amount of heat conductive adhesive, towards the outer edges near the copper windings where most of the heat originates. I cut each heatsink down from 6 " to 3 " in length

The right side, I attached 4 of the heatsinks at the 12 - 3 - 6 - 9 o clock positions..the left side I attached 4 of the heatsinks
at the 2- 5 -8 -11 o clock positions.

I then took the ebike out on the dirt trails which normally gets the motor side casings hot to the point that its uncomfortable to hold my hand on it for more then 5 seconds. The heat sinks dissipated enough heat to allow me to hold my hand on the motor without discomfort , but I could still tell the motor was hotter then I wanted.

I came home, took the heat sinks off and then drilled several 1" holes exactly where each heat sink strip had been placed earlier and then reattached the heatsinks over thos holes. I thought the cooling effect would be greater if the heat from the inside of the motor, did not have to first go thru the aluminum side cover , then go thru the aluminum heat sink ....but
only have to go thru the heat sink to reach the cooling effects of the outside air. This was a success. I did the same run on the dirt trails, and the motor was only slightly warm .

This was a win win situation, in that the holes I made in both side covers, allows the heat to dissipate thru the aluminum heat sinks that cover the holes , but ensure that no dirt, water, humidity can enter the holes which are covered by the heat sinks .

This worked so well, I would imagine that eventually, manufacturers of hub motors will apply it to the design of their products. The aluminum heat sinks with fins, allow much better heat dissipation when they are used as the only barrier between the heat of the inside of the motor and the coolness of the outside air/ wind chill effects as the ebike is in motion.

 

[USAEBIKECO]

Do you have any images of what you did ?

 

[ebikedelight]

Do you have any images of what you did ?

My wifes away visiting relatives and she has the digital camera. When she returns, Ill try to get some photos uploaded.

This mod really worked better then I anticipated. Its simple and effective..and takes away the hassles of messy oil cooling , installing fans and having large open holes for moisture/ dirt to enter the inside of the hub and cause problems.

Its so simple, it seems no one else has done it before .

On another note, I ran the 1000 watt hub motor I have, up to 2500 watts on several occasions, on these dirt trails, and the motor still did not overheat.

Thats how successful this mod was.

 

[Samd]

Pics would certainly be good.

 

[Nobuo]

Very interesting, Is there some way to avoid that in the future, the heat sinks won't accumulate dirt and lose their capacity for dissipating the heat? Also what material do You use to attach the sinks secured?.

Do you use something like these? http://es.aliexpress.com/store/prod...al-Pad-For-IC-Packages/126942_1472597253.html

They had thermal adhesive included

 

[dogman dan]

Blows my mind that the motors have no cooling ribs inside the spokes, right on the magnets, if it is a direct drive. It would require a larger flange for the spokes, just to get them laced. But that larger flange would also be a cooling fin.

On the other hand, size the motor right for your needs, and you don't have to cool the case so much. Bear in mind, you can have melting solder inside a motor who's case is cool to the touch, if you push a motor enough.

I've done it, and many others here have too. Sides are cool, big deal. You can still be melting the windings. I liked some small, ineffective cooling holes. They don't cool the motor, they let you smell how hot your winding is. 8)

The best way to cool your motor is to get the right, big enough for what you are doing, motor. I'd love to see a bigger gear motor. Larger diameter, with some pretty wide magnets, even if it wouldn't fit in 135 mm. Something that had the advantages of a Mac, but would run cool all day pulling 2000w.

 

[ebikedelight]

Blows my mind that the motors have no cooling ribs inside the spokes, right on the magnets, if it is a direct drive. It would require a larger flange for the spokes, just to get them laced. But that larger flange would also be a cooling fin.

On the other hand, size the motor right for your needs, and you don't have to cool the case so much. Bear in mind, you can have melting solder inside a motor who's case is cool to the touch, if you push a motor enough.

I've done it, and many others here have too. Sides are cool, big deal. You can still be melting the windings. I liked some small, ineffective cooling holes. They don't cool the motor, they let you smell how hot your winding is. 8)

The best way to cool your motor is to get the right, big enough for what you are doing, motor. I'd love to see a bigger gear motor. Larger diameter, with some pretty wide magnets, even if it wouldn't fit in 135 mm. Something that had the advantages of a Mac, but would run cool all day pulling 2000w.

I agree, its best to buy a motor that can perform as needed , without fear of it overheating , but its neat to be able to buy these 1000 watt hub motor kits for $193 , and run them at 2500 watts , and they perform without burning out the motor , just by doing a simple cooling mod , that is inexpensive and effective.

By drilling out the aluminum side plates, and covering those holes with the heat sinks , it provides advantages.

The heat sinks, with their cooling fins, are the only material between the buildup of heat inside the hub, and the cooling air outside of the hub . Just attaching the heat sinks to the aluminum side covers, means the heat inside the hub motor has to try and dissipate thru 2 seperate mediums....the aluminum side covers and then the heat sinks...which is not as effective as my modification....which allows the heat to dissipate only thru 1 medium...which is the heat sink....and the heat sink is specifically designed to dissipate heat , with its cooling fins...unlike the aluminum side covers which do not do a great job of heat dissipation on their own.

 

[ebikedelight]

Another advantage of the heat sink, is it is of thinner material then the aluminum side covers , so the heat penetrates better thru the heatsink in the areas where the side covers have been drilled out and covered with the heat sink.

On another note, Ive read many opinions about painting the outside of the hub side covers/ heat sinks , black . IMHO, this does not give a significant advantage with heat dissipation , and will actually cause more heat problems, when riding the ebike in the summer months, when its 100 degrees out and the sun is beating down on the black side covers of the hub motor. I will keep the aluminum heat sinks , silver in color .

The real test of my modification will be in the heat of the summer . I wanna see how well the cooling effect works when pushing the motor to 2500 watts , when its 100 degrees out and sunny.

 

[ebikedelight]

Blows my mind that the motors have no cooling ribs inside the spokes, right on the magnets, if it is a direct drive. It would require a larger flange for the spokes, just to get them laced. But that larger flange would also be a cooling fin.

On the other hand, size the motor right for your needs, and you don't have to cool the case so much. Bear in mind, you can have melting solder inside a motor who's case is cool to the touch, if you push a motor enough.

I've done it, and many others here have too. Sides are cool, big deal. You can still be melting the windings. I liked some small, ineffective cooling holes. They don't cool the motor, they let you smell how hot your winding is. 8)

The best way to cool your motor is to get the right, big enough for what you are doing, motor. I'd love to see a bigger gear motor. Larger diameter, with some pretty wide magnets, even if it wouldn't fit in 135 mm. Something that had the advantages of a Mac, but would run cool all day pulling 2000w.

If I had decided to just drill open holes in the hub motor , and leave it at that, I would attach a 90 degree elbow to at least 2 holes, to force air into the hub motor , and force it out the other elbow, upon each revolution of the wheel. Im just not a fan of drilling holes and leaving them wide open, because it allows moisture/ debris to enter the hub motor.

Humidity alone can cause alot of problems with moisture buildup when these hub motors are modified to be a open system.

 

[ebikedelight]

Very interesting, Is there some way to avoid that in the future, the heat sinks won't accumulate dirt and lose their capacity for dissipating the heat? Also what material do You use to attach the sinks secured?.

Do you use something like these? http://es.aliexpress.com/store/prod...al-Pad-For-IC-Packages/126942_1472597253.html

They had thermal adhesive included

I used longer heatsinks...and I used a silver conductive adhesive....since silver is probably the best heat dissipator.

The heat sinks themselves dont seem to buildup debris. The only thing that could clog em up, would be mud...and you can just squirt that off with a hose , since the hub motor is still closed up . All the holes I cut in the side covers, are covered up with heat sinks . The holes are drilled in the side covers, to allow the heat inside the hub motor, to dissipate faster and more efficiently thru the heat sink fins. If you just attach the heat sinks directly on top of the side cover , without holes under the heat sinks, then the hub motor heat has to go thru 2 mediums , making the cooling less effective.

 

[ebikedelight]

heres the adhesive I used...

http://www.ebay.com/itm/201309506383?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[cal3thousand]

I like your idea. It would be interesting to compare it against holes without heatsinks and heatsinks without holes.

[moderator edited to remove quote of deleted inflammatory material]

 

[ebikedelight]

From my own observations...just attaching the heat sinks , without drilling the holes, helped to dissipate more heat , compared to not having any heat sinks.

But drilling the holes, then covering the holes with the heat sink, gave better heat dissipation. I think if a person were to ride their ebike , and not push it beyond the motors specs and not plan on riding in 100 degree summer days, with the sun beating down on the hub motor, then just attaching the heat sinks, would be enough. I plan on pushing my 1000 watt motor, to 2500 watts , on hot summer days, on trails....so I went with the method of cooling that seemed to give better results.

[moderator edited to remove quote of deleted inflammatory material]

 

[999zip999]

Ebibikedelight. Do not fan a mythical Greek God he may have his father strike you down with a lightning bolt as he is told me his father is the god of lightning and electricity. Beware this is a warning. You have not heard of the God of electricity.
Or you could just wake him up from his state of dream.
He posts this stuff all over the place.

 

[cal3thousand]

I would like to know if this does better than plain holes. Maybe someone can throw some science into this theory that I don't know. What I do know is that air is a relatively poor conductor of heat, so you may be on to something with the heatsinks over holes. I'm just wanting some evidence that is less anecdotal before I go buying heatsinks.

I'm subscribing to this thread in the hopes that some scientific data can be had of this idea.

[moderator edited to remove quote of deleted inflammatory material]

 

[ebikedelight]

I was gonna purchase a infrared heat reading gun...to make the measurements more precise, but it was not needed in my situation . I could easily feel the difference in heat dissipations when comparing

1. hub motor, without holes or heat sinks

2. hub motor, with heat sinks

3. hub motor , with holes drilled, and heat sinks attached over holes.

#3 easily proved to provide the best cooling scenario..and its a simple, inexpensive mod , that isnt messy, like oil cooling , and it keeps the hub, a closed system , to keep out contaminents.

[moderator edited to remove quote of deleted inflammatory material]

 

[ebikedelight]

when my wife returns from vacation..ill try and get some photos uploaded...some people also wanted some close up photos of how I built and attached my battery holder to my ebike frame...so Ill try and get that done also.

 

[999zip999]

Got to have pic's of both of this. Boy's get busy.

 

[spinningmagnets]

Here's a thread on a variety of temp sensors. I'm embarrassed to admit that I havent actually acomplished anything with temp sensors yet, but they look to be cheap to acquire and run...time-consuming to pull apart a motor and mount inside on the stator, though...

"Temp sensor thats too cool not to share" 3 pages
http://endless-sphere.com/forums/viewtopic.php?f=1&t=25502

 

[made_in_the_alps_legacy]

I would like to know if this does better than plain holes. Maybe someone can throw some science into this theory that I don't know. What I do know is that air is a relatively poor conductor of heat, so you may be on to something with the heatsinks over holes. I'm just wanting some evidence that is less anecdotal before I go buying heatsinks.

I'm subscribing to this thread in the hopes that some scientific data can be had of this idea.

[moderator edited to remove quote of deleted inflammatory material]

well...
air is a poor conductor, but the cooling here relates to convection (means heat picked up by the air motion)
[edited post partly kept]

so... with drilling holes below the heat sinks, he reduced the conductive thermal resistance locally to zero since remaining thickness is zero. the heat gets then a chance for a prefered conduction way to get out (less thickness, less conductive resistance), chance which is even increased since on the outside, the surface to release that heat by convection is high (fins)

...just guessing from what he wrote

 

[Ykick]

Pics would certainly be good.

Yes please...

 

[SloNEZ]

Subscribed!

 

[ebikedelight]

I would like to know if this does better than plain holes. Maybe someone can throw some science into this theory that I don't know. What I do know is that air is a relatively poor conductor of heat, so you may be on to something with the heatsinks over holes. I'm just wanting some evidence that is less anecdotal before I go buying heatsinks.

I'm subscribing to this thread in the hopes that some scientific data can be had of this idea.

[moderator edited to remove quote of deleted inflammatory material]

well...
air is a poor conductor, but the cooling here relates to convection (means heat picked up by the air motion)
[edited post partly kept]

so... with drilling holes below the heat sinks, he reduced the conductive thermal resistance locally to zero since remaining thickness is zero. the heat gets then a chance for a prefered conduction way to get out (less thickness, less conductive resistance), chance which is even increased since on the outside, the surface to release that heat by convection is high (fins)

...just guessing from what he wrote

yes.... removing the sections of the flat aluminum side cover , by drilling holes in the areas where the most heat is generated, and then covering those holes with the aluminum heat sinks , it seems to allow much better cooling thru convection / wind chill effect. Each heat sink has several cooling fins , which allow the moving air to circulate thru it and dissipate the heat better , compared to that same air just flowing over the flat surface area of the poorer conductive flat aluminum side covers. The aluminum side covers dont seem to do a great job of dissipating the heat and this can be proven by pushing the limits on your hub motor, and getting it hot , then timing how long it takes for the aluminum side covers to cool down . We know that once those side covers get very hot, in stock format, they dont cool down quickly , ecspecially if you bring the ebike to a standstill...this proves that the aluminum side covers are very ineffective at dissipating the internal heat...and because those side covers are often painted black on the outside, it sucks the heat in externally from the blaring summer sun .

Its quite simple really...all this mod does is remove strategic portions of the poor heat conductive side covers , where the most heat is initially generated , and attach aluminum heat sinks in those areas , which are manufactured to specifically remove the heat as quickly as possible. This means the heat doesnt have a chance to continually build up as easily inside the hub , thus making the hub internals and complete hub side covers very hot.

I think another reason this worked so well, is because the heat sinks are placed exactly where the heat is generated. Attching the heat sinks to the center of the hub, would probably not be nearly as effective because the heat is not being dissipated at the source and is being allowed to radiate thru the whole hub internally and have a more cumulative effect .

 

[made_in_the_alps_legacy]

I don't know if you saw my previous post history but I was initially under the impression that those holes were "open" on the heatsink side too

(meaning you drilled not only the hub flanges but also the base of the heat sink, but not its fins)
because there has been some cooling attempt to drill holes on the hub flanges in a way that air is "pumped" Inside the hub like an axial/radial pump, close to the axle on one side, as far as possible from the axle on the other side, rotation centrifugating air)

you would loose on that "high conduction" heat preferred path effect but you would gain on the "convective heat pick up" effect by washing away the heat being built up Inside the hub

(just an idea...)

 

[ebikedelight]

I don't know if you saw my previous post history but I was initially under the impression that those holes were "open" on the heatsink side too

(meaning you drilled not only the hub flanges but also the base of the heat sink, but not its fins)
because there has been some cooling attempt to drill holes on the hub flanges in a way that air is "pumped" Inside the hub like an axial/radial pump, close to the axle on one side, as far as possible from the axle on the other side, rotation centrifugating air)

you would loose on that "low conduction" heat preferred path effect but you would gain on the "convective heat pick up" effect by washing away the heat being built up Inside the hub

(just an idea...)

I like the idea of being able to cool the motor down adequately, while keeping it a relatively closed system. I ride alot of trails, gravel roads in my area and having open holes in the side covers is a invitation for problems in my situation.

Its possible that drilling holes in the heat sinks would result in better cooling, but the current system im using, results in enough cooling effect to suit my needs.

In other words...lets say my motor wont get above 150 degrees, with my current mod.....and if I drilled holes in the heat sinks , it would lower that temp by another 10 degrees or so....im not sure that insiginficant temperature drop , is worth the hassles of a open system where debris, water, humidity can now easily enter the hub internals and cause problems down the road.

This modification has resulted i me being able to push my 1000 watt motor, to 2500 watts and it only gets very warm..compared to it usually getting quite hot.

I dont think a very warm hub motor, when pushed to its limits , is gonna have any real negative effects in the long run { glue melting off magnets , wires burning up ,etc } . What we are trying to accomplish is to take the " very hot" scenario out of the equation, and this mod seems to do it, for my needs. The real test comes in about 3 months, when summer is here , its 100 degrees out, with full blaring sunshine , and then pushing the motor to 2500 watts, and seeing how well the cooling is.