Definitive Tests on the Heating and Cooling of Hub Motors

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fechter   100 GW

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

Post by fechter » Feb 07 2017 10:25am

Quokka wrote: The motor temp stayed cool... really really cool. Was running about 30 degrees cooler on the same hills, but was going faster. Not only does the motor run cooler but the motor seems much more powerful at lower temps?? It feels like an absolute animal now. Does anyone know if torque goes down as motor temp goes up?
Absolutely. The winding resistance goes up as it gets hotter, which will reduce the current you get at a given voltage. With cooler temps, not only do you get more torque, but the motor is operating more efficiently (which reduces heating).
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by sketchism » Feb 08 2017 9:19pm

Quokka wrote:
Quokka wrote:
Quokka wrote:Just installed a set of hubsinks on a QS205 pushing 10kw on my Qulbix Q76R.

Went for a few fangs around the block, hotest i could get the bike 80-85 degc. Its not the same hot conditions as the last test but i do think it doesnt get anywhere near as hot.

Just gave my bike an absolute hiding. Now running ff and hubsinks. Adaptto on boost with ovs 3 at 120amps. Temp here is mid 30's and i tackled the same route i did in my first test with just hubsinks. Air temp is around 10 degrees cooler. The motor temp stayed cool... really really cool.

Only way i see that i could hit the temp cut out would be a really steep hill (actually i mean a mountain) at full throttle. There is nothing like that here so i am done :D
Bottom line, i think it lowered the temps by at least 20deg c. Probably more

haha your cheque is in the mail,, jks but great to hear the combo is working for you in our aus summers, thats where they were developed so it's a great proving ground!

the part about feeling more powerful is hard to quantify just from the seat of the pants dyno but i noticed the same thing, as resistance increases with temp, keeping the stator cool lets it run more efficiently/powerful for the same input as the current isn't being wasted as extra heat
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by ABritInNY » Feb 19 2017 12:33am

I just opened my pre-owned MXUS v2 that I bought as a spare and was preparing it 4 hub sinks by ferrofluiding it. Once inside I discovered old dried up ferrofluid on the magnet ring and I'm curious if it needs to be totally removed before fresh is added, or is it ok to just dump a fresh wet dose on top.and be done with it? If it's ok to leave do I need to adjust the amount? I was planning on 5ml, although the poster above seems to have put 10ml in. I thought Justin had said 5ml was optimal and more just created more drag.
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by mrbill » Feb 19 2017 12:56am

ABritInNY wrote:I just opened my pre-owned MXUS v2 that I bought as a spare and was preparing it 4 hub sinks by ferrofluiding it. Once inside I discovered old dried up ferrofluid on the magnet ring and I'm curious if it needs to be totally removed before fresh is added, or is it ok to just dump a fresh wet dose on top.and be done with it? If it's ok to leave do I need to adjust the amount? I was planning on 5ml, although the poster above seems to have put 10ml in. I thought Justin had said 5ml was optimal and more just created more drag.
HI ABritInNY:

If memory serves, the "magic" amount of ferrofluid is 1mL per 50cm^2 of stator surface area. Based on my own observations, as you increase the amount of ferrofluid you get slightly better heat-conducting at the expense of noticeably greater drag. Assuming the MXUS motor stator has a 20cm diameter the sweet spot is about 5.65 mL. I'd probably err by overfilling it slightly at 6 mL to make sure I get most of the heat transfer benefit.
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by redline2097 » Feb 24 2017 1:45am

How much more continuous power the Mxus V3 can handle with only hubsinks?

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

Post by macribs » Feb 24 2017 5:12am

@redline that is very hard to tell, as the inside of the motor still got the air bridge - and that air bridge is not a great thermal pathway.
If you first do hub sink I recommend adding ferrofluid as well to get best possible thermal pathway.

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

Post by Offroader » Feb 24 2017 12:41pm

redline2097 wrote:How much more continuous power the Mxus V3 can handle with only hubsinks?
I would estimate not very much at all, like 5%.

I found that my MXUS turbo shell didn't get hot while riding.It was much worse than the cromotor, which got a lot hotter.

You can easily test it yourself, ride your bike and then quickly stop and feel the motor, specifically the magnet ring. It will only feel slightly warm. This means that hubsinks are not going to do much at all. You need the FF.

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

Post by spinningmagnets » Feb 24 2017 3:00pm

If you only get one, get the Ferro-Fluid (or ATF), either one of which will transfer heat from the stator to the aluminum side-plates....after you get those, then the fins will add some help. I would not use fins by themselves IMHO...

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

Post by Offroader » Feb 24 2017 4:50pm

Heat sinks are a waste unless you are trying to cool the motor faster while stopped for long periods of time. They will help in that instance as the hub does get really hot even without FF when stopped.

When moving, they won't do much. You can test it for yourself by simply just touching the motor and feeling how hot it gets while moving. If the magnet ring isn't getting hot then heat sinks won't do all that much.

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

Post by Cowardlyduck » Feb 24 2017 10:42pm

Actually I've found heatsinks do still help even without FF. Yeah it's no where near as much as with the FF, but it's not insignificant.

Where they really make a difference is once the stator becomes heat soaked as by that point the magnet ring and side covers are also getting very hot.
I've found that once I hit and maintain about 90-100C on the stator, the heatsinks soak up enough heat to be too hot to touch, even just after moving. I've also added thermal paste between my side covers and magnet ring so I'm not sure if that helps.

All that being said, unless your adding fan cooling or vents like me, there is no point not using FF together with the heatsinks.
OTOH, if you want every last bit of performance from your motor, and can't use FF, then adding heatsinks for that extra few % might make sense. :)

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

Post by sketchism » Feb 26 2017 9:57pm

Offroader wrote:Heat sinks are a waste unless you are trying to cool the motor faster while stopped for long periods of time. They will help in that instance as the hub does get really hot even without FF when stopped.

When moving, they won't do much. You can test it for yourself by simply just touching the motor and feeling how hot it gets while moving. If the magnet ring isn't getting hot then heat sinks won't do all that much.

Just to be clear you don't have heatsinks installed do you?

To be fair that advice is actually not in line with the findings of everyone who runs them, nor the findings of the beta testers, as mentioned by cowardly duck above as well
Last edited by sketchism on Feb 27 2017 10:02pm, edited 1 time in total.
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by Offroader » Feb 27 2017 12:24am

sketchism wrote:
Offroader wrote:Heat sinks are a waste unless you are trying to cool the motor faster while stopped for long periods of time. They will help in that instance as the hub does get really hot even without FF when stopped.

When moving, they won't do much. You can test it for yourself by simply just touching the motor and feeling how hot it gets while moving. If the magnet ring isn't getting hot then heat sinks won't do all that much.

Just to be clear you don't have heatsinks installed do you?

To be fair that advice is actually not in line with the findings of everyone who actually runs them nor the findings of the beta testers, as mentioned by cowardly duck above as well
Take into account that comment is when NOT using FF. It was in response for someone who wants to use sinks without FF. My findings were that sinks wouldn't be worth it without FF unless you are letting the motor cool while stopped.

You really want the FF when using hub sinks.

But you can test for yourself, as each motor is different, how well sinks will work with your motor. Simply, touch your motor magnet ring and see how hot it is getting. Touch it right after you stopped moving to see how hot it is getting while moving.

I have found that my hub exterior is cool to the touch while my bike is in motion with no Ferro Fluid, so sinks would not do anything if the surface of my motor is not getting hot. However, if I let my bike sit still for a few minutes, it does get slightly warm.

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

Post by litespeed » Feb 27 2017 12:53am

Sorry to state the obvious but you should not have said that, period. It's misleading, unfounded and hurtful to all the hard work that was put into those. You should publicly apologize!

Do your air cooling and let other do the FF and Hubsinks! Don't be a bully.

I'm done.

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

Post by Cowardlyduck » Feb 27 2017 6:14am

Alright, well in an attempt to distract everyone from this pointless argument I'll throw in an update to my FF + Fan cooling endeavours.

If you'll recall, my last motor (HS4080) ended up consuming most of the FF I added when it reacted with the red insulating varnish.
https://endless-sphere.com/forums/viewt ... 0#p1198704
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The red varnish then mostly wiped off when I removed the FF:
Image

Well it seems this time around it's a different story. I opened up my Leaf '1500W' motor which is basically the same setup as my HS4080 with fan cooling, red varnish, FF and heat sinks, however this time around the results seem much more promising:
Image
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Image
Image

As you can see, it's not perfect, and there is some grit that made it's way into the FF, but not so much that I am concerned about it after more than 2000km on this motor since adding the FF. The other nice surprise (compared to the HS4080) is the FF is mostly still there. It does not appear to have reacted with the varnish this time around.
I 'think' I used statoraide type A in this motor, where as I used type B in the HS4080. Does anyone know which was which? That would indicate that one of them reacts with the red varnish while the other does not. Another factor was I did use more FF in this motor than the HS4080. I think I used about 4-5ml in the 4080, where as I used about 6ml in this motor.

After wiping down the magnets and laminations, nowhere near as much of the varnish was removed compared to the HS4080. The small amount that was could be put down to rubbing from when I removed the stator, and/or rubbing from grit in the FF, but I don't think the FF itself reacted with the varnish this time around.
Image
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So I'm not exactly sure where that leaves the whole debate on using FF together with varnishes....or together with vented/fan cooled motors, but from my perspective it now seems a whole lot better than it did last time around. I'm glad I tested this on more than one motor with both types of FF. Before everyone goes out and buy's whatever the type A stuff was though, consider that I could have used type B....I wish I kept a better record of which one I used, but based on the ~4ml being left in the type A syringe I still have (I used all of the type B) and I know for a fact I used more than 5ml in this motor, I'm 90% sure I used type A.

Part of the reason I think the levels of grit/dirt contamination into the FF was quite low even though I'm pulling air in/through the motor with my fan setup is due to the way the air travels through the motor. The vent holes pull air across the winding end turns, then through the centre of the motor, then out the vent holes on the other side. The area with the FF on top of the stator and around the magnet ring does not have air pulled past it, leaving the FF to do it's thing with little chance of dirt/grit getting caught up in there.

The reason I have this motor apart is to replace the fans due to a mistake (over-voltage) on my part that fried some of them. I think this time around I will reverse the flow direction as I found that last time the hot exhaust onto my rear brake rendered it mostly useless during prolonged or heavy braking conditions.
Once that's done, I will re-add the 4ml I have left of my FF type A to this motor as I now think it's actually viable to run both air cooling and FF together.

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

Post by Offroader » Feb 27 2017 12:44pm

litespeed wrote:Sorry to state the obvious but you should not have said that, period. It's misleading, unfounded and hurtful to all the hard work that was put into those. You should publicly apologize!

Do your air cooling and let other do the FF and Hubsinks! Don't be a bully.

I'm done.

Tom
I'll say what want here as I'm not offending anyone and keeping it on topic, I'm putting a lot of my time into cooling hub motors and think I can discuss these issues here with people. Show me one instance where I'm bullying anyone. Mabe you can argue I'm bullying FF + heat sinks, but who the heck cares if I am bulling that?

I feel like questioning FF and hubsinks is the same as questioning if the world was the center of our solar system hundreds of years ago, I've even thought of this for weeks and your post just confirms it. Why are some of you guys so defensive about your FF + hubsinks? I'm just simply trying to find the best cooling method. Why do some of you care so much and get so defensive? I've noticed this defensiveness for a while here about the FF, like it is a protected religious thing. I'm just kind of sick of it now, this is a forum about research and progress, I can question the FF + hubsinks and shouldn't be treated like I'm attacking someones religion.

You mention Hard work? I don't even want to mention how many hours I put into my setup, I'm not complaining. This is mostly a hobby after all.


I can see sketchism not liking it because he is selling the hubsinks, but he is actually being fair about the discussion considering he has personal stake in the business. Although he doesn't do a simple test of showing me the external magnet ring temperature while the bike is in motion. I still wonder why he can't do a simple test, or is it possible the magnet ring is cooling sufficiently fast as long as you are cruising along with your bike without sinks, like I have found.

That post above you commented on was in direct response to someone who was asking about sinks without FF, and after others told him sinks with FF is not worth it, just go back a page and read for yourself. I agree it is somewhat confusing if read out of context, but certainly not worth making a post about it telling me to stop bullying people about FF, especially after I responded back to the post to stop any confusion and not seem like I'm attacking your guys precious hub sinks and ferro fluid.

I'm also not bullying anyone, I'm even telling people to specifically check their exterior magnet ring temperature by touching it at various times to see just how hot things are getting and that will tell them how well sinks will work. This way they can see for themselves and not just take my word for it.

I've asked people to check their temps for me after finding that my magnet ring was not getting hot if I was at a speed over 15MPH while riding, even when I had an internal fan turned on at super high speed and the winding temp held at 115C, the magnet ring was just cool to the touch while riding. It took me just a short 20 seconds of riding for my magnet ring temperature to fall from a burning hot 75C (got hot only after bike sitting for a long time) to a just slightly warm temperature while moving.

My own tests showed that the motor will cool itself rapidly without sinks while the bike is in motion. However, I've said that if the bike is stopped this isn't the case, the motor will get very hot. But my motor won't even get hot while stopped unless I ran an internal fan while stopped, as I DON'T have FF.

Not one person has done this simple test for me to simply check how hot their exterior motor temperature is getting. Not even Skethism who makes the hub sinks and has certainly read my posts about my findings where I questioned this specific issue. This issue was very important because it showed me there was a bottleneck in the heat transfer and hubsinks and FF will only do so much.

Why can't he simply ride his bike at above 15MPH or higher, and simply just stop the bike and touch his magnet ring to see how hot it is getting?

I've always said FF will work, I've never said it wouldn't and have said mostly everyone is better off using FF over air cooling. I've modified my motor for air cooling and used it for 2 summers on a cromotor and it works. It eliminates overheating on my hard runs. I'm just questioning how well FF + sinks work, because it is a lot easier to use them compared to my air cooling setup.

I want to find out if FF + hubsinks will do the same, because I don't want to put oil in my motor and then find out it doesn't work as well. I need to use silicone in my motor and have lots of outside air running through it so the last thing I want is an oily mess inside.

I would gladly switch over to FF + hubsinks if it will work, or even work somewhat close to my more complex cooling setup. Just shows that I'm not attacking it in any way, just comparing with the intent to switch over because it is far easier to use.


It is also this post which concerns me, someone who used oil and sinks and an MXUS motor is complaining that he still overheats and is looking for something better. It concerns me because I never have to stop to let my motor cool off with my setup.
https://endless-sphere.com/forums/viewt ... 5#p1246285

I know in the end I'm going to have to convert my motor over to FF to finally find my answers But I'm going to wait a summer so I know the limits of my current cooling setup to better compare the two. When I finally do convert over this should finally settle the question as to what works better.

If the FF works better or just as good, I'll say that my cooling setup sucks and not worth it.

Some of you guys have to stop acting like FF + hubsinks is a religion and maybe there could be better alternatives. Maybe you guys haven't found the holy grail and there are better alternatives out there. Remember in the end its just some oil and aluminum you are getting so worked up about.

Like I have said in one of my early posts, I'm specifically trying my air cooling setup to try and promote research into the area. I want progress made in this area, not just take it to heart that FF + hubsinks is the best and you can't even question other cooling methods because you may INSULT some peoples hard work.

I'll say this again, read over anything I have said in the past, it is all about questioning the effectiveness of cooling, not attacking anyone personally. Remember, it is guys like me who question things and find alternatives that make progress throughout history. It is guys like you who stifle it with having a closed mind.

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

Post by Offroader » Feb 27 2017 2:03pm

This is a test I would like to see from FF + hubsink user.

Temperature of the external magnet ring while riding at various speeds when using FF and without hubsinks.

Temperature of the external magnet ring while riding at various speeds when using FF and hubsinks.

Temperature of the external magnet ring right after stopping, to see how long it takes for the magnet ring to heat up while stopped.

It would be preferable to use a wireless temp probe for the test but a laser temp probe will work fine.

This test would help confirm a lot of information on how well a hub sheds heat while in rotation with and without sinks. Because my very basic test is showing me that a rotating hub will shed heat far faster on the exterior than it can get heated internally.

This is probably because the thermal resistance through the magnets and about 6mm of steel.

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

Post by liveforphysics » Feb 27 2017 5:05pm

Hubsinks and FF are definitely synergistic. Many of us have smoked a motor motor winding or two while the outside shell of the motor was cool to touch (where heatsinks wouldn't be helping much). That said, if the motor doesn't burn up and you keep riding hard the shell eventually warms up and hubsinks would become beneficial, even with no FF, as eventually the shell heats with or without FF.

When my new Nyx frame build get's on the dyno, I will try to get a baseline continuous power level (by letting power be motor temp limited), then FF the motor and get a continuous power level, then add hubsinks and get a continuous power.
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by Cowardlyduck » Feb 27 2017 5:32pm

I'm just gonna try and ignore/stay out of this whole argument, apart from to say that a lot of the stuff people are now raising has already been discussed before and the answers to some of your questions are buried in various threads including this one if you search. When I first got into E-bikes back in 2011, I managed to burn up a motor (stock HS3548) within the first month of owning my Stealth Fighter. For a very long time after that I used thermal stickers on the magnet ring to very roughly determine the motors temp state. It was reliable enough that it prevented me burning up any more motors.....and it did get hot while riding.
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Re: Definitive Tests on the Heating and Cooling of Hub Motor

Post by Offroader » Feb 27 2017 6:28pm

cowardlyduck, what you could possibly do is if you want to use FF and a fan, you could use silicone to seal the sides of the stator to prevent air flow from getting up near the gap where the FF is.

All you would have to do is run a line of silicone around the edge of the stator, put vaseline on the side cover so the silicone won't stick to it, and you have a reasonably sealed duct blocking the stator magnet gap.

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

Post by Cowardlyduck » Feb 27 2017 7:06pm

Thanks Offroader, that's not a bad idea. I'll give it some thought and might do it. The only catch that springs to mind is if the silicone will stick now that I've had FF on the windings.
What would happen if chunks of silicone started coming off in a operating motor?

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

Post by Rix » Feb 27 2017 7:52pm

liveforphysics wrote:Hubsinks and FF are definitely synergistic. Many of us have smoked a motor motor winding or two while the outside shell of the motor was cool to touch (where heatsinks wouldn't be helping much). That said, if the motor doesn't burn up and you keep riding hard the shell eventually warms up and hubsinks would become beneficial, even with no FF, as eventually the shell heats with or without FF.

When my new Nyx frame build get's on the dyno, I will try to get a baseline continuous power level (by letting power be motor temp limited), then FF the motor and get a continuous power level, then add hubsinks and get a continuous power.
Luke, can't wait to see this happen.

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

Post by RageNR » Feb 27 2017 8:32pm

So question..
I am interested in using some of the smallest hub motors available with decent power/weight ratio. I am thinking in the 250-350w range.
My criteria:
- as small (physically) or as close to the size of an IGH as possible
- ability to handle up to 96v, motor on front + rear with combined over-peak output of ~1000w
- lightest as possible (2-3.5lbs)

The idea behind this is to add 2 additional motors to a bike with a mid-drive, and capable of giving a boost of up to 1000w when needed.
I want them small for 2 reasons: To look like an IGH instead of a motor, and to add as little weight to the bike as possible.
Reason for 96v is that's what I am eventually planning to run on my mid-drive.

I see no other way to use a low power motor in this manner unless it will be cooled with FF and heatsinks. Assuming it could even handle the voltage.

Do any hubmotors out there exist that could even remotely fit this scenario?
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sketchism   100 W

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

Post by sketchism » Feb 27 2017 10:19pm

Offroader wrote:
I can see sketchism not liking it because he is selling the hubsinks, but he is actually being fair about the discussion considering he has personal stake in the business. Although he doesn't do a simple test of showing me the external magnet ring temperature while the bike is in motion. I still wonder why he can't do a simple test, or is it possible the magnet ring is cooling sufficiently fast as long as you are cruising along with your bike without sinks, like I have found.

Why can't he simply ride his bike at above 15MPH or higher, and simply just stop the bike and touch his magnet ring to see how hot it is getting?
I don't want you or anyone to get the impression i am discouraging looking for alternative cooling methods, experimenting with new ideas is my favorite thing to do, i just wanted to point out that when you said 'heatsinks are a waste" which was a statement made from an assumption that wasn't from your own findings thats all.

i've offered to send you a set for free in a previous post as well simply because someone as interested in cooling as you are should have the opportunity to personally experiment with all the available methods, i understand my passion for heatsinking hubs can be taken as a bias now, but i developed the HubSinks as a result of that interest( and early testing results), rather than becoming an advocate for them after they were developed.

i thought i had posted videos clearly showing the difference between rides with and without the sinks? consistently hitting thermal cut off without them, and staying well under with them installed, what did you want tested specifically? Justin and Luke have sets of the HubSinks and will be testing them at some stage also which will give us quantifiable data :) the short answer to how hot the magnet ring is when not using hubsinks while i ride is, very hot, 70-80C when i hit thermal cut off during steep offroad rides


here is a hill climb video with and without SInks (both with FF)
https://youtu.be/2iGj6ANZyps

With HubSinks installed sees a temp of 91C at the point the stock motor hit thermal cutoff at 124Cpeak&115 nominal
then at 67c at the bottom of hill with sinks vs 84 stock, on a 25 degree day riding 2km distance and ~400M elevation (average 18% grade)

The difference off-road or in general riding is more pronounced than a constant climb because of the increased rate of cooling between accel spurts

here is a video of the TT1500 Bike race with the two bikes with prototype Heatsinks almost lapping the rest of the field and coming 1st and 2nd with a 20 second lead over 3rd place (also the race another competitor with the same motors burned out the motor trying to keep up ... no names... hyena haha)
https://youtu.be/OzSnfHcen1w
Don't overheat your ebike hub motor - www.hubsink.com (beta testing still open)
https://hubsink.com HubSink - Hub Motor Heatsinks

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Hyena   100 GW

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

Post by Hyena » Feb 27 2017 11:02pm

Wait, CD are you running FF with a hub peppered with holes around the rim ? It doesn't leak/fling out ? I tried some in a hub with an unplugged hole and it rapidly leaked out (though to be fair it was a lower temp grade and I did boil it)

As for the hubsink argument, as sketch said belting around the track at the EV race it was clear the difference the same motors could take between hubsinks and not. I melted mine and the other 2 bikes running sinks sustained high power handling and kept pulling ahead to take a convincing win.

I also went on a test ride with Sketch where we abused the shit out of the motors on some steep, twisty, slow speed single track. We were constantly hard on the throttle then the brakes through this tight, twisty trail - basically the quickest way to kill a hub with alot of time spent dumping big kw as heat at the low efficiency end of the curve. The hub was barely warm to the touch at the end and we took IR themometre readings. I'll have to edit and upload the video. To me, it's an impressive testimonial to how well FF and hubsinks work.
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RageNR   100 W

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

Post by RageNR » Feb 27 2017 11:27pm

I watched that race. Had no idea you guys participated here on the forum. Pretty cool. oh, and awesome rigs btw 8)

I do not have much skin in this particular dept., but would the heatsinks not start becoming effective until the motor was saturated with heat?
Meaning that unless you ride the hubmotor hard and heavy constantly (like in that race), the heatsinks would not make much of a difference?
I'd still like to see someone figure out how to make an external cooling solution work, with radiator, coolant, and fan.
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