Oil cooling your hub- NOT snake oil!

[Sancho's Horse]

I saw your link to the extrusion site. Fourier's law...the amount of area has a significant effect on the potential for cooling...temperature difference as well. I used laminations of builder's flashing. It works really well, although I have oil move through the lamination stacks, and I have not really had time to work out how well the flashing works on its own.

However, my childhood neighbor spins aluminum. He has been spinning a racing carb cover which looks like it would be well adapted to some of the things I am doing, so I might add this. He is in his late eighties, from Kentucky, makes nearly every fruit and vegetable into alcohol, and is a total riot. He is viral material all on his own, and he says it is cool for me to videotape and post. I promise, I will post on all of my cooling experiences, but busy right now trying to bang out a pedicab trailer.

 

[bowlofsalad]

Some people complain about having a lot of issues with leaking oil it seems. Has anyone tried making most of the gaskets out of something like a large neoprene sheet and some sharp razor blades? I probably don't understand the process of sealing up a motor well. But I imagine using something other than some sort of gasket material, such as that gasket goop or glue or whatever it is, would be very hard to deal with, setup well and then open the motor afterwards.

 

[amberwolf]

Neoprene would probably dissolve with a number of the "oils" being used for cooling--at the least it is porous and might not make a very good barrier.

Unfortunatley the "goop" type stuff is almost the only thing that really seals that well, other than the types of materials used to seal ICE type systems up--but I'm not sure if those come in uncut sheets large enough to make your own gaskets, and even if they do it might be difficult to torque the covers down tight enough on them to prevent leaks, and/or need longer screws than what comes with them.

Another problem wiht anything ohter than "goop" types of sealant is that you may not be able to apply any other types to several areas that need to be sealed (around the axle, wires, etc). .

 

[izeman]

it's not the cover leaking. that's easy. as you said cut a gasket (their are big sheets you can buy and cut as you wish) - or just use liquid gasket. the problem is the cable slot. this just is not easy to be made oil leak proof. it was not designed to be that. glueing it and putting heaps of silicone around the place where the cable enters the slot is a nice idea but not really leak proof.


Sent from my iPhone using Tapatalk 2

 

[melodious]

Some folks on the this thread that have committed themselves to this modification have made sure that their hub motor wires are beefed up and the hall sensors are firmly in place before the oil goes in and any sealant or gasket is placed. That way you have a solid motor that hopefully would not need servicing for the entire lifespan.

Personally, only reason to use oil is if your going high performance (aka high wattage) applications. Most of us don't really need this mod. If any mod that's worth the effort probably would be the drilling of the side covers & installing fan blades & protecting the hub insides with some type of industrial high strength corrosion resistant sprays (i.e. Boeshield).

Edit: I actually read some of my post here. I know I'm not perfect, so I knew KNEW there would be some blunder here harhar.

So the word on the street is that fan blades DO make a considerable amount of heat dispersal? I'm LOST on this matter.

 

[Kris B Krunch]

So what's the most power any of you have been getting out of your geared hubs reliably after oil cooling them?
I'm looking at replacing my controller so might be running 60v and 40 amps.... But could always tame it down a little with the cycle analyst. What do you guys think? I have a BMC v2t in a 26" rim on a kona stink-E

PS, I'm possibly thinking of going with a 60amp controller just to be future proof, or too crank up the power for a two mins burst just for fun with the BMC

 

[Stevil_Knevil]

I have a couple DD hub motors that have been modified with larger phase wires, drive-side fill & vent holes, then rebuilt using silicone sealant.

It seems the accumulated experience here is that liquid cooling works better than air-cooling techniques, and MUCH better than nothing.. ..until it leaks

*Thinking of a water-based solution*

When I was a volunteer firefighter, I remember that we had a 5 gallon bucket of 'Water Wetter' that we could draft from at the pump, then feed to the nozzle. It was supposed to help the water 'stick' to the side of vertical surface. Not sure what was in it, surely not petro-based. It was incredibly slimy.

Can anybody think of a reason why something like this->
[youtube]dbAwRYFAPEo[/youtube]
would not work well in a hub motor (particularly when it leaks) ?

 

[wojtek]

Personally, only reason to use oil is if your going high performance (aka high wattage) applications. Most of us don't really need this mod. If any mod that's worth the effort probably would be the drilling of the side covers & installing fan blades & protecting the hub insides with some type of industrial high strength corrosion resistant sprays (i.e. Boeshield).

i see it bit differently - the better the cooling the smaller / lighter motor can be used to achieve certain level of power. Lighter is ALWAYS better.

 

[The Stig]

Can anybody think of a reason why something like this->
http://youtu.be/dbAwRYFAPEo
would not work well in a hub motor (particularly when it leaks) ?

Haha nice video. Is it water soluble though???

So what's the most power any of you have been getting out of your geared hubs reliably after oil cooling them?
I'm looking at replacing my controller so might be running 60v and 40 amps.... But could always tame it down a little with the cycle analyst. What do you guys think? I have a BMC v2t in a 26" rim on a kona stink-E

PS, I'm possibly thinking of going with a 60amp controller just to be future proof, or too crank up the power for a two mins burst just for fun with the BMC

60a should be fun but I don't know if the our geared hubbies would like it. You need to have an EB3 infion/lyen mk2, otherwise use a throttle tamer by zombieSS. Try it but keep your ears open for symptoms that might lead to one of 3 possible parts of the motor going POOF!
Freewheel clutch/one way bearing
Gears
Keyway

I'm wondering if fat tires with lower air would help these motors survive high torque + shock torsional loading.

 

[Stevil_Knevil]

Can anybody think of a reason why something like this->
http://youtu.be/dbAwRYFAPEo
would not work well in a hub motor (particularly when it leaks) ?

Haha nice video. Is it water soluble though???

Yes, a blast of water would clean off any leaks.

Also considering a blend of vegetable glycerin, xanthan gum and distilled water (gleaned from the awkward side of YouLube )->
[youtube]rcakT7JcA4Y[/youtube]

Forgot to mention that the innards of these motors were treated with 2 coats of Boeshield T-9, so rust will not be an issue..

 

[deepfraught]

Just some numbers riding a couple months on a new unit with CA3 and upgraded MAC 8T from EM3EV on 14S nominal 50V, same town as Matt so probably similar terrain.
I get a similar speed average and top to Matt's first post, but using low power mode 50% 750W throttle limit, in these summer months has been 52degC operating norm, 64degC on bursts of 1300-1500W power modes 2-3 for any short steep climbs.
I saw 75degC end of ride long hill in peak afternoon ambient temp 35degC yesterday.
The responsiveness of throttle use and temp fluctuation sounds as Matt described, and I'm assuming our temperature sensors/displays are correct.
Mine not oil cooled, so I was wondering what the difference to Matt's and mine would be to make the difference, if not absolute shift errors in the sensor.
The bike it is on with an Alfine 8 rear hub, deep V rim, 700x28c rear tyre, 26x1.75 front with front hub, can pedal to 30kph without great effort follow road bikes pushing 35kph before needing the motor.

 

[parabellum]

Ok. ATF loosened glue under magnets in MXUS 500W and the whole ring of magnets was spinning inside on hill climbing and so. About 1 1/2 year after oil filling. Used cheap abro steel epoxy to get running again.

 

[The Stig]

lol good one Parabellum

Deepfraught did you get any oil-free numbers to compare to?


Since I went with oil cooling as an experiment with my Ezee motor I've learned a couple tricks. 1) With sealing the wire hole in the axle, and 2) A new type of breather for hubs. I will add them to the "noobs guide to hub motor oil cooling" at some point


Note to self: other things to add to noobs guide: Misc materials, like cardboard to cover the floor, oil pan etc

 

[John in CR]

Anyone with an oil cooled hubbie break through 100mph yet? How about haul a 400lb load up a couple of miles of 20% continuous grade hitting over 50mph on straights long enough to permit it? Air cooling FTFW and no worries about your magnets coming off either. LOL!

 

[deepfraught]

Deepfraught did you get any oil-free numbers to compare to?

Yep half asleep when posting, I updated this morning with clearer explanation of numbers.
Basically I'm seeing the same numbers as Matt after his oil cooling, I've never seen the high numbers he first posted.
I gathered there was a problem with the motor and it was "half baked" and the oil cooling was a way of dealing with that?

 

[parabellum]

Anyone with an oil cooled hubbie break through 100mph yet? How about haul a 400lb load up a couple of miles of 20% continuous grade hitting over 50mph on straights long enough to permit it? Air cooling FTFW and no worries about your magnets coming off either. LOL!

I have few neodim magnets sittind on the fridge, there is no coating left because of oxidation in 1 year and often I cross rivers and watter filled holes where hub and sometimes wheel is fully sumerged. Finaly, how should I ride on the beach sand with holes in the hub? :lol:

 

[The Stig]

Parabellum FTW ... Ok so hes not techinically hating... What a show off! :| I'm interested in oil cooling for low speed off road riding

Deepfraught not sure where to look for the clear comparison but to answer your question no my motor didn't get baked, I'm doing it for the reasons above.

 

[deepfraught]

Roger Stig, I guess instead of choosing a heavy stator direct drive to heatsink, the (correct) oil for a geared hub can do the equivalent trick.
I would also want a 12T MAC and spare gears as someone suggested.

 

[The Stig]

12T MAC check, I've got some other tricks up my sleeve too so hopefully I can get this machine built soon to show em off.

 

[sardini]

I am using plain water... after the stator hits 90 degc.

i am testing this for 3 months now and the motor looks like new. Trails are not a problem anymore...
just remember to clean and paint the motor with insulation varnish.

 

[itchynackers]

I've been oil cooling since 2012 (Pikes race). In the 2 years of use, I haven't seen any magnet loosening etc.. The key to this whole issue is finding a suitable vent. You cannot/should not completely seal the motor. The air/oil inside WILL expand (like freezing water breaking a rock). The oil WILL come out somewhere. If you have sealed the rest of the motor properly, then it will come out the axle slot along the wires, and even inside the insulation of the wires. The key is to control the leakage. I've been looking for an automatic 2-way vent for a while now. It should begin to vent (gas) at maybe 1psi. I was kind of hoping Justin would do the hard work for me and find a suitable vent.

Adam

 

[The Stig]

My idea, in a nutshell, is to force the motor to breathe through the drive-side bearing. It would require upgrading bearing on the brake-side to a bearing with better seals.(or alternatively downgrading the drive-side bearing, or weakening it's seals slightly)
This is without having done any research yet, and having first sealed the wire hole and all other parts of the motor... The drive side bearing is shaded from water by my 7speed freewheel cluster, at least on my bike it is. Any oil that seeps out would go straight onto the freewheel cluster, onto the cogs and on to chain... And cause the pedal drive system to be more efficient maybe you woudn't even need to lube it anymore. Just top up the motor oil every 6 months or so.

 

[Marc S.]

My idea, in a nutshell, is to force the motor to breathe through the drive-side bearing. It would require upgrading bearing on the brake-side to a bearing with better seals.(or alternatively downgrading the drive-side bearing, or weakening it's seals slightly)
This is without having done any research yet, and having first sealed the wire hole and all other parts of the motor... The drive side bearing is shaded from water by my 7speed freewheel cluster, at least on my bike it is. Any oil that seeps out would go straight onto the freewheel cluster, onto the cogs and on to chain... And cause the pedal drive system to be more efficient maybe you woudn't even need to lube it anymore. Just top up the motor oil every 6 months or so.

That was basically how the initial oil filling in my Bafang BPM2 worked. I can tell you it was quite a mess!

When I repaired the BPM2 (shot clutch after 4,000km) last year I installed new ball bearings and took off the inside facing seal of the bearings in the side covers.
Instead of the initial 80-90ml ATF filling (filled to about an inch under the axle), I use about 60-65ml ATF now and have a well lubricated, very well free-wheeling, but CLEAN hub motor that runs relatively cool as well.
The motor breathes happyly through the axle hole/motor wire without any additional sealing of the motor. Only the motor wire is shortened to about 5cm (2") to prevent oil from wickening out.

Currently (got a new Infineon 12FET controller last week) I use the BPM2 with 20s/10Ah LiPo battery and 25A controller for 65km/h (40mph) top speed in my trike. Till last week I used a 15s battery and 35A controller for trouble free 5,000km (after the repair) on my 40km daily commute.

 

[The Stig]

Yeah I can't be sure the sealing of my motor wire is perfect, I used liquid electrical tape. And yeah whether breathing through the drive-side bearing or the wire hole the oil level needs to be well below the axle, but also the hole where the wire enters the axle on the interior of the motor needs to be facing down. The difference between our breather methods is, on my motor the wire hole is on the break-side so if a get an oily mess there I'm in trouble because it can get on the breaks. Whereas if it gets on my chain drive system it may actually help me! If someone is going through the trouble to open their motor, the break-bearing upgrade could be seen as just a diligent step in adding some more insurance that your break-side bearing won't leak onto your break rotor.

 

[h0tr0d]

What do you guys think about this?
http://rnmsolutions.wordpress.com/2014/02/26/oil-cooling-of-electric-motors-and-controllers-with-nanofluids/

Looks like a good solution for hubmotors