Cooling fans inside Hub motors

[Cowardlyduck]

Great stuff Offroader.

The race is on! I'm making progress too.

My controller is mounted.
I've still got a good amount left to do, but should have things up and running within a few weeks I think.

Cheers

 

[pendragon8000]

CD that looks boss. What's the inside like? Standard aluminum fet block? How many FETs?

 

[Cowardlyduck]

CD that looks boss. What's the inside like? Standard aluminum fet block? How many FETs?

Thanks!
I made this mod without opening up the controller so I could keep my warranty.
The Adaptto Mini-E is only 6 Fet, but they are good quality Fets and stock it can take up to 65A.

I'm going to see how it goes at 65A first. I don't currently have a battery that can put out much more than that anyway.

Cheers

 

[Cowardlyduck]

Do the fans you use take vibration ok from rough trails etc. Also how many watts is you dc to dc converter can you post a photo

The fans I ran previously took everything I could throw at them...vibrations, pot holes, corrugations, jumps...Cattle grids!...and even water, mud and dust...
[youtube]iMIEGfayg30[/youtube]
That motor still has those fans in it...it's just completely wrecked from the winding damage from an unrelated mishap I think I talked about previously in this thread.

The DC-DC converter used for those fans was a little 15W unit from Lyen here on ES, but I don't think he has any left now.
I integrated it with a few other components...details here.
Running the fans through that DC-DC was a bit of a pain though, and it got pretty hot pushing those 12V fans at up to 18V. I ended up cooling the DC-DC with another couple of fans blowing across it as well! :lol:

My new setup doesn't use a DC-DC. It just runs directly off the main battery. By running enough fans in series, I don't have to worry about a DC-DC any more.

Cheers

 

[Offroader]

Making the air duct has been harder than I thought. I have been trying different ways to make it but haven't been happy with any. It really needs a tight seal or the air will just recirculate. I want mostly outside air to be run through the motor.

I decided to finally do it right and will attempt to mill out a custom plastic air duct that will screw into the bolts that hold the stator together in my cromotor. This is really the only way to do it I think, especially to get around the halls and phase wires. I'm going to leave a small gap between the air duct and the side cover so that I can apply silicone caulk. Before the caulk dries I will place the side cover back on to seal the silicone against the side cover, of course using a mold release on the side cover so that it doesn't stick. This should give me an almost air tight seal that is sturdy and won't fall apart.

 

[Cowardlyduck]

I'm glad you want to do it right Offroader...it would be a shame to go to all this effort for it not to be effective.

I've had some setbacks with my controller setup, but should have things up and running soon I think.

Cheers

 

[Cowardlyduck]

Even though I've had some setbacks...I still did make some progress.
[youtube]Dnldx2MBQFo[/youtube]
Still a work in progress, but this is what they sound like on ~57V.
I did quickly test effectiveness and they seem to work well, cooling the hub from 33C at idle down to 30C in a few seconds. Turning them off and the motor went back up to 33C :? ...while still at idle. My temp sensor is embedded in the windings so I'm not sure why it went back up and I retested and got the same result.

My other temp sensors (Big red display where the CA used to go) wires fell off, so I'll have to fix that now too.

Cheers

 

[pendragon8000]

I thought wow that's quiet... Then you turned it on haha. Sounds OK though. What do you think CD? Is it too loud in real life?

 

[Cowardlyduck]

I thought wow that's quiet... Then you turned it on haha. Sounds OK though. What do you think CD? Is it too loud in real life?

It's too loud to use in crowded area's or bike paths without attracting attention, but I'm fine with that as that's not where I will be needing the fans anyway.

For off-road hill climbs, tight/twisty single track, mud/sand, and other heat generating scenarios, it's not too loud at all as there are rarely other people around anyway. I'm yet to take it up to speed with the fans running, but I reckon at anything over 40kph I won't be able to hear them anyway.

Cheers

 

[kiwiev]

Hey Blake

Sounds cool!!!!

There will be no stopping now.

Its like the sound from my sonic.

[youtube]aZAFkOEr6UE[/youtube]

 

[Offroader]

Decided to start working on my EDF cooling. With the summer heat my bike is pretty much not drivable after using around 30% battery capacity. At this point the motor heats up in seconds and even taking 30 minute breaks doesn't cool it down enough to last for like a minute at full throttle.

Started to mill the air dam, should finish it tomorrow and have it mounted. I'm pretty much figuring out how to do this as I go along as I rarely machine anything. You guys with the 3d printers would probably have an easy time I think making it. Oh well, at least I get my milling skills up for when I have to mill metal.

 

[madin88]

i'm really keen to see all components mounted inside the motor and how it works. do you also install cooling fins on innerside of aluminum stator, or just leave a gap?

 

[Offroader]

i'm really keen to see all components mounted inside the motor and how it works. do you also install cooling fins on innerside of aluminum stator, or just leave a gap?

I actually have the large 60x150mmx25mm heatsink and had a plan on how I was going to cut it up into smaller heat sinks and attach them to the curved surface inside the stator. If the stator in that area gets hot and pulls a lot of heat from the windings then the heat sink would increase the surface area of the stator in multiples, it should really help getting the heat into the air with it's tall 25mm fins.


However, I decided there was no rush to mount them right away because I want to test how well the cooling alone works. Then I will just open up the motor and add them and then see how much of a difference adding them make.

I do really wonder how hot the stator gets and how effective it is at removing heat from the windings. If the aluminum stator on the cromotor does pull a lot of heat from the windings, which is questionable because the stator seems insulated from the windings, then adding the heatsnks would make a huge difference when using fans. I figure that the stator may get hot with a sealed hubmotor because it absorbs the heat like the sidecovers absorb the heat, but with an unsealed fan cooled motor, the stator really shouldn't absorb that much heat and makes adding heat sinks pointless.

 

[John in CR]

Decided to start working on my EDF cooling. With the summer heat my bike is pretty much not drivable after using around 30% battery capacity. At this point the motor heats up in seconds and even taking 30 minute breaks doesn't cool it down enough to last for like a minute at full throttle.

Your issue isn't heat dissipation, heat generation is. Your controller settings are inappropriate for the motor, gearing, and load.

 

[Offroader]

Decided to start working on my EDF cooling. With the summer heat my bike is pretty much not drivable after using around 30% battery capacity. At this point the motor heats up in seconds and even taking 30 minute breaks doesn't cool it down enough to last for like a minute at full throttle.

Your issue isn't heat dissipation, heat generation is. Your controller settings are inappropriate for the motor, gearing, and load.

I'm not to sure about that although it is good to make sure that isn't the issue. My motor takes a while to heat up but once it gets to about 90C, it is at the point where any load will send it above 100c very quickly.

The motor just can't cool itself being all sealed up like that and pushing 6K watts with a lot of offroad riding.

The reason I doubt it is my controller is that the cromotor runs much cooler with the Max-E vs my old Lyen 18fet. I also get about 20% more range and I use the autodetect settings numerous times already and supposedly they work well with the cromotor. Another reason I don't think it is the controller settings is that even letting the motor cool for 30 minutes after it has fully heated up, it will still heat up super quick probably because the stator is fully heated at that point. That being said I should manually mess around with the settings to see if I can make the motor run cooler.

It is just the summer weather that brings this problem out in a big way. In cooler weather it is much less of an issue.

 

[Allex]

I guess what Mr John is trying to say is that your best bet to a cooler motor is to use:
1. lower phase amp settings
2. smaller wheel size
3. be more gentle on the throttle

But I dont think that above three points are very interesting for you

 

[Offroader]

I guess what Mr John is trying to say is that your best bet to a cooler motor is to use:
1. lower phase amp settings
2. smaller wheel size
3. be more gentle on the throttle

But I dont think that above three points are very interesting for you

ahh, OK, yes you are right. I thought he was talking about the problem like Hyena just mentioned on the adaptto forum about going around the block and his motor was already heated up.

But yes, it wouldn't be that fun and I'll say that I have been cutting my rides short now once my motor gets fully heated, takes about 800 watt hours for that to happen but that is only about 35% of my battery capacity.

Hopefully this cooling mod will allow me to go as hard as I want until I use all my battery capacity.

 

[John in CR]

I guess what Mr John is trying to say is that your best bet to a cooler motor is to use:
1. lower phase amp settings
2. smaller wheel size
3. be more gentle on the throttle

But I dont think that above three points are very interesting for you

LOL!!! Riding with a properly tuned system is always more interesting than pulling your pud stopped on the side with an overheated motor, and proper setup and tuning certainly doesn't require lower performance.

 

[John in CR]

I guess what Mr John is trying to say is that your best bet to a cooler motor is to use:
1. lower phase amp settings
2. smaller wheel size
3. be more gentle on the throttle

But I dont think that above three points are very interesting for you

ahh, OK, yes you are right. I thought he was talking about the problem like Hyena just mentioned on the adaptto forum about going around the block and his motor was already heated up.

But yes, it wouldn't be that fun and I'll say that I have been cutting my rides short now once my motor gets fully heated, takes about 800 watt hours for that to happen but that is only about 35% of my battery capacity.

Hopefully this cooling mod will allow me to go as hard as I want until I use all my battery capacity.

You already have numbers, so research the necessary formulas and crunch them to find out how much air flow is needed to move a given amount of heat. It's a real eye opener. It's so much better and easier not to make some of that heat to begin with, and you don't have to give up performance to do it.

 

[Cowardlyduck]

John, I'm pretty sure any sub 10KG hub motor pushing a 100KG+ bike + rider in challenging/steep off-road conditions is going to heat up no matter how 'properly tuned' or 'properly setup' it is.
I managed to completely melt down the windings on my stock Stealth Fighter soon after I purchased it thanks to challenging off-road conditions. I'm pretty sure you wouldn't say Stealth don't have a properly tuned, or setup solution.

If your 'solution' would be to use a heavy hub motor in a small wheel then your only thinking about on-road performance. For on-road that might work, but not for steep/technical off-road scenarios like me and Offroader like to ride.
I'm pretty sure we've already covered this earlier in this thread John.

Cheers

 

[John in CR]

John, I'm pretty sure any sub 10KG hub motor pushing a 100KG+ bike + rider in challenging/steep off-road conditions is going to heat up no matter how 'properly tuned' or 'properly setup' it is.

Heat up, sure....overheat, not necessarily. That is unless you mean 100kg + bike + rider like you typed.

... I'm pretty sure you wouldn't say Stealth don't have a properly tuned, or setup solution.

You melted yours, so there's your answer...of course I would.

If your 'solution' would be to use a heavy hub motor in a small wheel then your only thinking about on-road performance. For on-road that might work, but not for steep/technical off-road scenarios like me and Offroader like to ride. I'm pretty sure we've already covered this earlier in this thread John....

I include necessary qualifications in my posts, and didn't say anything about a heavier motor or small wheel or street riding. Follow bad advice and examples at your own peril. This is all physics at its purest, and not rocket science difficult. There are quite simple ways to reduce the heat a motor makes, often without giving up significant performance, and if you don't get how much better it is to get rid of heat before you make it, then you're likely to continue having heat issues.

Do you know the resistance of your motor? Have you even roughly calculated the amount of heat you need to deal with? How much air flow do you estimate is required to remove it? Those are the starting points. I've warned people multiple times about axial fans not working well when near restrictions. Air will always flow via the path of least resistance, so "recirculating" is likely to be only a small % of your lower than expected flow.

Apparently my input isn't welcome. That's fine, so I won't post here anymore.

John

ps- For offroad riding in demanding technical terrain, the only good solution is a mid-drive, and the weight of that motor will depend on the durability you want and noise level you're willing to tolerate, along with of course the power/performance level you demand. Light guys who put in plenty of pedal assist may be able to get away with hubbies in-wheel, but it's still a significant compromise.

 

[Cowardlyduck]

John, I respect your (and all peoples) opinion. Apologies if I came across as rude.

You raise some valid points...in an ideal world, we would all run perfectly capable and tuned systems for the terrain we ride, but in the real world this is not the case.
In my case I use a hub motor (even for tough off-road conditions) because of it's simplicity, low noise, and Regen capabilities. I am ok with and fully understand the drawbacks of using such a motor in off-road conditions, but to me the benefits outweigh the drawbacks. The biggest drawback is heat...that is why we are attempting to address the heat issue here.
I suspect based on the countless other E-MTB builds and manufactured bikes intended for off-road use (like the Stealth) that use Hub motors, I am not the only one who thinks they can be made to work...even for demanding technical terrain.

Anyway, you can claim we are doing it wrong all you like, but at the end of the day we will either succeed or fail in achieving what we are trying to do (remove heat effectively). I think my earlier mod/tests show it can/does work...I don't see why that gets ignored now.

Cheers

 

[Offroader]

So my air duct came out almost perfect and I notched the holes for the halls wires to go through.

I had to place another order for parts, I need tiny long screws to hold down the air duct securely. Hopefully they will arrive tomorrow.

The last and only step I can't predict is how well the silicone will work filling in the small gap between the side cover and air duct. I want an air tight fit so there is no recirculation of air, even a small gap will allow most of the air to recirculate instead of pulling in fresh air.

The issue is I milled it with a plastic "Delrin" that is not great for silicone or anything to stick to it. I did this because it was the cheapest and easiest plastic to mill. From my test however, it seems if I rough the surface the silicone should stick well enough. I am also going to tap tiny holes in the top of the air duct for the silicone to flow into and hopefully help secure it. The gap between the side covers and the plastic air duct is only about 1-2mm which must be filled in with silicone caulk.

How I'm going to fill in the gap between the side covers and air duct is put Vaseline on the side covers, then apply silicone all along the top of the air duct and press on the side covers. This should mold the silicone between the air duct and side covers. When everything dries the Vaseline which supposedly acts as a mold release for silicone should allow the side covers to be removed while the silicone is still stuck to the air duct making a perfect seal. Any surface unevenness will just be worn away in the silicone by the spinning motor.

 

[Cowardlyduck]

That's awesome Offroader. I can tell you've definitely thought this through.
I try and do things properly, but often end up getting frustrated and just take the bigger hammer approach.

Cheers

 

[sn0wchyld]

I thought wow that's quiet... Then you turned it on haha. Sounds OK though. What do you think CD? Is it too loud in real life?

It's too loud to use in crowded area's or bike paths without attracting attention, but I'm fine with that as that's not where I will be needing the fans anyway.

For off-road hill climbs, tight/twisty single track, mud/sand, and other heat generating scenarios, it's not too loud at all as there are rarely other people around anyway. I'm yet to take it up to speed with the fans running, but I reckon at anything over 40kph I won't be able to hear them anyway.

Cheers

you could always get a simple dc-dc converter from ebay and either wire the voltage pot to an external pot so you could adjust yourself, or i imagine it'd be pretty simple to get an arduino and a 2nd temp probe and make the Vout temperature dependant, so it automatically ramps up as things get hot...