Definitive Tests on the Heating and Cooling of Hub Motors

[John Bozi]

18 fett beefed up lyen (last time it was programmed and I had a CA it was reading 67a) but it jumps that limit for bursts

motor was one of those cheapest possible ebay ones. black with clear indented alu rings visible on the outside. its pretty generic... Only thing I have changed is tripple or more the phase wiring up to the axle...

note I undid bolt and nut to see how strong thermo paste is.... been riding like this this year.

 

[sketchism]

Yeah all those factors do matter.

You know what is funny Justin named this thread the "definitive tests" .

to be fair i did publish the exact stats for how much heat energy (not motor power, that depends on what % efficiency your motor is operating at, 10KW input at 90% efficiency is around 1000W of excess heat etc) they dissipate at a given speed while i was developing them, and since then its been amazing seeing everyone finally solve their overheating problems combined with the FF.

it's just a matter of calculating how much excess heat you're generating and whether or not the sinks will be able to dissipate it fast enough, (granted the hotter they get the higher the Delta T and the better they work)

the data can be extrapolated from the raw stats too, have a look at calculating the amount of surface area they are adding and the ability for that aluminum surface to shed heat

over the past few months i've been loving the conversations about your alternate method and i appreciate that you're looking for the absolute best option, if effort/time investment into the motor is no question i dare say combining your forced ventilation with FF and sinks would shed the most possible excess heat other than true liquid cooling with a pump and external radiator


speaking of leaf motors, i've found them to be quite a nice little package for what they are, capable of handling far higher than their rated power indefinitely when able to shed the excess heat

 

[Cowardlyduck]

speaking of leaf motors, i've found them to be quite a nice little package for what they are, capable of handling far higher than their rated power indefinitely when able to shed the excess heat

Yup, agree with you 100% there! My Leaf motor combined with forced fan cooling, FF (4ml) and heat-sinks (not hub-sinks, but smaller little epoxied sinks from before hub-sinks were a thing) makes for the best combo of light weight and decent power at ~5KW.

I can still over-heat it on very steep or long climbs, but it sheds the heat fast and I only ever have to stop and let it cool if I go nuts. Dialling back the power slightly (dropping from Boost (70A) to Normal (45A) on my Adaptto) is enough to prevent overheating on almost every hill.

Cheers

 

[burningwings]

I love Justin and the contributions he has made . My experience with Statoaid: the motor cry 3540 R with cooling fins , the test continuous acceleration with no cooling period between accelerations , start 65volts at 100 amps . Run until thermal cutoff of 110 C reached . Motor stock 17 runs , motor Statoraid added 18 runs , 120 CC soybean oil added 47 runs ! Flat terrain at 80 degrees The motor was allowed to cool between runs . Got a new 3540R from Grin with statoraid added . I have relocated to the Tarzana hills outside of Los Angeles . My street and most all of the streets are VERY steep 10% grade I would say ! Took out my bike on a 96 degree day and got about half a mile up the hill before overheating ! My bike is useless in current form ! Statoraid is USELESS under high power applications as it is plain to see ! 65 volts at 35 amps ! Going back to oil and trying to solve leaking oil from wire side . I believe the Grin cooling fins work if you can get the heat to them which Statoraid will not !

 

[John Bozi]

what speed are you attempting the 10% grade at 65v 35a?

If you stay near bogging speeds it will cook probably the same as upping your power to get through it quicker in better rpm.

A motor full of oil definitely has more path, sealing it and not damaging something will be interesting.

What grin fins?

 

[spinningmagnets]

Burningwings, I think if there is some way for you to swap your hubmotor into a smaller rim (20/24-inch), then I think you find that it runs on hills better. I don't know if the improvement will be enough, but it may be worth trying as that would be much cheaper than switching to a mid-drive system.

 

[Offroader]

The showdown will commence shortly, Forced air vs Statorade + hub sinks. Can the Statorade + Hub sinks even come close to the best modified forced air cooled hub motor known on the forum, which is proven not to overheat under most conditions?

I have the spokes, Hub sinks, & Statorade. Just have to lace up the wheel and run the tests.

You will get an unbiased review of how well the statorade + hubsinks work from someone who can compare it against a modded fan cooled motor that doesn't overheat.

Testing will be done at 7500 Watts, that is what my bike peaks at now and what I have been using for the last couple of years. Also overdrive will be turned on so that 7500 watts is also being peaked and sustained on the street.

I drive the bike very aggressive and always at full throttle, constantly pushing 7500 watts.

Both motors are identical Cromotor v3s, including same 17" rim and 3" tire run at low PSI.

NOTE: I can overheat my fan cooled motor if I full throttle it up a very steep dirt hill, so steep that I'm running about 15% of my top speed at full throttle and have to lean forward on the bike so I don't flip back, yes it will overheat after a while. But that is rare that I ride up such a steep dirt hill as these are only found inside the woods, there is no hill on the street or paved street that cars drive on that will overheat it at full throttle.

 

[eyebyesickle]

The showdown will commence shortly, Forced air vs Statorade + hub sinks. Can the Statorade + Hub sinks even come close to the best modified forced air cooled hub motor known on the forum, which is proven not to overheat under most conditions?

NOTE: I can overheat my fan cooled motor if I full throttle it up a very steep dirt hill, so steep that I'm running about 15% of my top speed at full throttle and have to lean forward on the bike so I don't flip back, yes it will overheat after a while. But that is rare that I ride up such a steep dirt hill as these are only found inside the woods, there is no hill on the street or paved street that cars drive on that will overheat it at full throttle.

IM WATCHING!



and planning to do some testing of my own! =)

I'm still in shock of the forced air cooling though, honestly. I'm loving it.

 

[John Bozi]

My favourite part of comparing the cooling systems will be the length of video to show the set up.

video one bolt up some fins, drill a hole, squirt, screw in a bolt.

video two?

 

[John Bozi]

sm,

mid drives can be cheap as chips, you can climb anything at low power all day at 5 kph.

EDIT: can't delete my own post

 

[sketchism]

The showdown will commence shortly, Forced air vs Statorade + hub sinks. Can the Statorade + Hub sinks even come close to the best modified forced air cooled hub motor known on the forum, which is proven not to overheat under most conditions?

Looking forward to hearing how it goes! keep us updated with vids etc as well, sounds like the toughest competition possible so it will be a great head to head!


incidentally i Guess it was only a matter of time.

I was contacted today by a manufacturer asking to confirm i gave permission for an exact copy of the HubSinks to be made. (very impressed with that actually)

They have an NDA policy for the enquiry so can't tell me the name of the person, only that they requested an exact copy in large quantity, and that this specific company won't do it, but they are sure someone else will.

If you see any dodgy HubSinks getting around, or ones sold from unofficial dealers can you let me know, i had to have an extremely large MOQ made and it would really be sucky if a copy was released and i never recouped my initial investment, although just seeing them work and help you guys out has been awesome. The design is no secret, all of my workings are on ES forum, but very disappointing.

 

[Offroader]

skethism:

When looking at your hubsink design I was wondering why you made the base so thick and the fins so thick? Could you not have used less material and made them lighter and a little thinner?

I know thickness does matter somewhat for shedding of the heat and acting as a buffer so maybe you designed it thicker for thermal reasons?

Maybe you could offer a lighter set or alternative in the future for people who want to reduce weight at the risk of the fins breaking more easily.

 

[macribs]

Those fins are made from aluminium and are feather weight. If I remember correct it is only 250 g or something. Use Ti bolts and save a few grams there. The fins are so light weight I can not imagine you will even notice any difference on ride quality, acceleration or braking. After all, wheel, motor and brake rotor is 40 times the weight of the fins.

The weight of the fins are like watching a fat dude eat with both hands at burger shop, stuffing down burgers after burgers while gulping milkshake and round of the meal with apple pie & sundae. Thx goodness he got diet coke with that order

 

[Offroader]

Those fins are made from aluminium and are feather weight. If I remember correct it is only 250 g or something. Use Ti bolts and save a few grams there. The fins are so light weight I can not imagine you will even notice any difference on ride quality, acceleration or braking. After all, wheel, motor and brake rotor is 40 times the weight of the fins.

The weight of the fins are like watching a fat dude eat with both hands at burger shop, stuffing down burgers after burgers while gulping milkshake and round of the meal with apple pie & sundae. Thx goodness he got diet coke with that order

The fins alone weigh in at 400 grams, I believe you could get the same performance at half the weight. But you are correct in the grand scheme of things 200 grams isn't all that much, especially if you are running a QS205, but it does add up with everything else.

 

[Ohbse]

Those fins are made from aluminium and are feather weight. If I remember correct it is only 250 g or something. Use Ti bolts and save a few grams there. The fins are so light weight I can not imagine you will even notice any difference on ride quality, acceleration or braking. After all, wheel, motor and brake rotor is 40 times the weight of the fins.

The weight of the fins are like watching a fat dude eat with both hands at burger shop, stuffing down burgers after burgers while gulping milkshake and round of the meal with apple pie & sundae. Thx goodness he got diet coke with that order

The fins alone weigh in at 400 grams, I believe you could get the same performance at half the weight. But you are correct in the grand scheme of things 200 grams isn't all that much, especially if you are running a QS205, but it does add up with everything else.

Sketch put a lot of effort into the design, modelling thermal characteristics and also for manufacturing. That's why they are as wide as they are, even though on majority of hubs you could fit additional width. I'm very sure your belief is mistaken.

 

[Cowardlyduck]

If your really worried about weight, feel free to copy my design. I haven't weighed them, but I'm pretty sure it would be substantially less than the hubsinks.

Cheers

 

[spinningmagnets]

"Let not the perfect be the enemy of the good". Both of them should work awesome, and either one would be a HUGE benefit over not having additional finned aluminum mass attached to the hub-shell...

And if you already have hubsinks, you can trim them down as light as you want, very easy.

 

[Offroader]

Those fins are made from aluminium and are feather weight. If I remember correct it is only 250 g or something. Use Ti bolts and save a few grams there. The fins are so light weight I can not imagine you will even notice any difference on ride quality, acceleration or braking. After all, wheel, motor and brake rotor is 40 times the weight of the fins.

The weight of the fins are like watching a fat dude eat with both hands at burger shop, stuffing down burgers after burgers while gulping milkshake and round of the meal with apple pie & sundae. Thx goodness he got diet coke with that order

The fins alone weigh in at 400 grams, I believe you could get the same performance at half the weight. But you are correct in the grand scheme of things 200 grams isn't all that much, especially if you are running a QS205, but it does add up with everything else.

Sketch put a lot of effort into the design, modelling thermal characteristics and also for manufacturing. That's why they are as wide as they are, even though on majority of hubs you could fit additional width. I'm very sure your belief is mistaken.

'

It could be, maybe the thicker fins will soak up more heat when the bike is stopped, and then be able to release more when you start moving. I assume there could be some hidden benefits of thicker sinks.

This is different than a computer heat sink which is cooled at a constant rate of air flow and no need to store any heat.

 

[sketchism]

skethism:

When looking at your hubsink design I was wondering why you made the base so thick and the fins so thick? Could you not have used less material and made them lighter and a little thinner?

I know thickness does matter somewhat for shedding of the heat and acting as a buffer so maybe you designed it thicker for thermal reasons?

Maybe you could offer a lighter set or alternative in the future for people who want to reduce weight at the risk of the fins breaking more easily.

spot on, during testing when i had a very thin base i found with varying airflow and big changes in load, they weren't able to absorb spikes quite as quickly so having some more material against the hub let them cool down further while not being heated creating a larger Delta T between stator and HubSink, which then let them absorb more heat from the stator when it was needed, working as a bit of a short term buffer, (similar to how the thick alu stator motors were better at absorbing spikes than the thin steel ones) the cost of the grade of alu i used wasnt inconsiderable, so thinner would have been much cheaper but less effective.

 

[Cricket_Swe]

Hey people, a question about Ferrofluid. Does it dry out if the motor is not in use? I would like to add ferrofluid and hubsinks to my motor but I don't actually have a bike to go with the motor just yet, so I can't use it. Let's just say that theoretically I wasn't gonna use the motor until spring next year, would it be terrible to install ferrofluid in my QS 205 motor now?

 

[parabellum]

Hey people, a question about Ferrofluid. Does it dry out if the motor is not in use? I would like to add ferrofluid and hubsinks to my motor but I don't actually have a bike to go with the motor just yet, so I can't use it. Let's just say that theoretically I wasn't gonna use the motor until spring next year, would it be terrible to install ferrofluid in my QS 205 motor now?

Ferro fluid Grin sells is some special formulation being sold or derived from audio grade ferro fluid, it should last years in use, in high temperatures which is the worst enemy, causing evaporation. In room temperature and with no dust it should last like forever.
On other hand, if the magnets cement is not resistant to the ferro fluid formulation it will soften over time and you could be very disappointed from your first ride, with magnets spinning in the rotor.

 

[Offroader]

Video of my 40mm EDF cooled motor in my MXUS turbo. This is what the FF + hubsinks is up against.

This is my 2nd update of the cooling where I used a layer of silicone on top of the windings to force more air through the windings instead of flowing above the windings.

This constantly blows air through the windings and out of the motor, at high speeds. The Fan speed is adjustable so can be turned higher, much higher, when more airflow is needed. Is rated up to 400 grams of thrust, 290 watts continuous power.

This should blow away any FF + hubsinked motor, LOL, no pun intended. It is constantly blowing out hot air out of the motor, directly off the windings, at high flow rates.

[youtube]VchIApATnH4[/youtube]

 

[macribs]

Wow that is a noisy little devil. Sure spins fast and moves air. I am not sure I could live with the noise. How bad is it when motor is closed and you are riding, still loud? The noise made feel like I was in the dentist chair......and I am not a big dentist fan.

 

[dvdrwsor]

I think the fins should be pointed towards the way of going, not to the sides. Not only because of the air resistance, but the same drag generates heat, which greatly affects efficiency of what they were designed for in the first place.
If you must do it this way for easy manufacturing, at least bend them at a spiral, pointed to the way of going, to make them somewhat aerodynamic, and to gather air, not slide through it.
I wasn't talking about your video, Offroader.
-non native english

 

[Offroader]

Wow that is a noisy little devil. Sure spins fast and moves air. I am not sure I could live with the noise. How bad is it when motor is closed and you are riding, still loud? The noise made feel like I was in the dentist chair......and I am not a big dentist fan.

I don't run it at high speeds most of the time, but in a sealed motor and you are sitting on the bike it isn't too bad. When riding on the street going above like 15-20 MPH you won't hear it, the wind noise will block it out completely. going slow the city background noise will block most of it out.

Where you are likely to hear it if you are deep in the woods where everything is really quiet.

Most of the noise gets pushed out the air holes to the side, so you hear it more if you ride by something that reflects the sound back at you. This 40mm fan can be run at slower speeds and be really silent with a reasonable amount of air flow going through the motor. So on really cold days it will be OK, where you need to turn the fan up is on those hot summer days. If you are driving slow around the city then just turn the fans off and it is silent again. The fans don't have to be run and can be used at different speeds depending on riding conditions.

The best way to describe the sound is like a noisy computer or server. You will ignore it mostly all of the time. But without a doubt, I would rather have it silent over any noise. It is nothing like how it sounds in the video with the camera right above the fan, you really only hear it slightly when the motor is sealed up and you are sitting on the bike.

You have to understand that most gas bikes are really noisy, they have fans and all, but nobody complains as you get used to it. My bike is more of a high powered electric dirt bike now, so it is going to need a little noise for the cooling and high performance. When I'm pushing it in the woods on the dirt hills, I'm having the fans on at a high speed to deal with the high heat.