Oil cooling your hub- NOT snake oil!

[TylerDurden]

- will wires drenched in oil ever be solderable again? or do they just need to be thoroughly cleaned in alohol and then soldering flux?
- suggesting on prepping metal surfaces already exposed to oil for jbweld/sealant? i'm not sure alcohol will be enough. i'm wondering if i have to grind the metal - the atf almost seems to penetrate metal surfaces...

I would wipe as much off as possible, then use brake-parts cleaner.

[fechter]

What's going on with the heat shring tubing? It looks like the ATF is attacking the plastic.
Perhaps a different variety of heat shrink is needed (Teflon?).
Soldering wire contaminated with oil is difficult. The oil wicks into the strands and is very hard to get out. I think with the right solvent, you should be able to clean it enough. Alcohol might not be the best stuff though. Something like brake cleaner or acetone might work better.

[hjns]

my questions:
- are there better ways to protect the wiring than shrinktube? after a week of usuage, it's starting to fall apart (note that this is midsurgery for a suspected hall issue):
or should it be completely covered in a deeper layer of jbweld?
- will wires drenched in oil ever be solderable again? or do they just need to be thoroughly cleaned in alohol and then soldering flux?
- suggesting on prepping metal surfaces already exposed to oil for jbweld/sealant? i'm not sure alcohol will be enough. i'm wondering if i have to grind the metal - the atf almost seems to penetrate metal surfaces...

I think that there is more expensive heatshrink available. The cheap stuff usually is graded up to 80oC, which is obviously not enough. Try something rated up to 200oC like this (brochure).

For removing oil, try a little bit of degreaser, like this one. Very expensive at digikey, though.

[GCinDC]

at the local hardware store, i almost got a general car motor cleaner/degreaser, but then they were able to find the brake cleaner and i went with that, and a couple sets of disposable gloves.


i'm so glad! the brake cleaner is AWESOME! i guess i was getting frustrated trying to clean oil with rubbing alcohol..

i'd started to worry i'd never be able to dry the stator out. i have no idea how it works, but it works!

after lots of paper towels:

after removing the silicone and a couple sprays of brake cleaner:


i can't wait to use the stuff on my oily brakes.

thanks, guys!

[amberwolf]

Regular household ammonia seems to do ok on taking oils off of surfaces, but it takes time and some scrubbing with certain things. Or "washing" with it, spray, let run, spray, let run, spray, let run, wiping if desired instead of letting it run off. Haven't tried it on cleaning out the ATF in the old 36V Fusin yet, but it seems to have done ok taking it off my rim and tire after the first leaks.

[GCinDC]

Any thought on how quickly the motor returns to ambient when oiled?

ambient was ~22C.

motor got up to 100C on the way home, but cooled down to 82C before i set up the camera and timer. i've edited it here to show the temp per minute. 27 degrees over 27 minutes, cools faster at first and slower at the end.


anecdotally, the motor cools down nice and quick when it's cooler out. on hot days, it doesn't cool down as fast.
it cools down nicely when the motors spinning and drawing < 1.5kw though i'll need to demonstrate this somehow.
it heats up very quickly (up to and over 100c) when bogged down in sand or up steep hill drawing 4kw.

i'd be happy to run more tests if you want. just let me know.

my questions are:
- an oil cooled motor is not necessarily a more efficient or powerful one, is it? it's just overheats less, right?
- how would it respond if i threw say, 2x the current at it?

here's a pic of how i sealed the wire slot, btw:

and added jbweld over the hall wires before fastening them down:

more pics in my build thread.

[parabellum]

- an oil cooled motor is not necessarily a more efficient or powerful one, is it? it's just overheats less, right?

Cooler motor is more efficient, cooper resistance grows with temperature.

[fechter]

Twice the current would have about 4x more heating. A cooler motor will be more efficient but the drag from the oil will add losses, so it might be nearly even.

[GCinDC]

two weeks hard riding and commuting. no leaks.

i'm thinking i could use some more oil in there. i still hit 100C after 3 miles of hard commuting, much less on trails and stuff. i don't expect more oil will change that but 100cc's really doesn't seem like that much in an hs3540, as i think a lot does get wicked into the windings. certainly doesn't feel like 1/4 full...

[electr0n]

GC does your commuting involve much hills? Are you accelerating hard from stops? What are your average and peak watts during your commutes? I want to bump up my HS to 24s and 65 amps when my batteries arrive. Not sure if I'm going to overheat.

[Sancho's Horse]

Sorry to be wading in without a working prototype, but I immediately knew I wanted oil cooling. I plan on using a hub motor in a mid drive set-up through a nuvinci cvt, and I will be hauling some weight on occasion. I am still working through some dimensional issues and calculating power (and cost) needs prior to placing a motor order, but I thought I might put my intentions out there.

I am going to install 1/4 inch 90* brass fittings at the periphery of the side cover, just shy of the spoke flange ring, and use aluminum tubing to connect fittings which lie directly across from each other on opposite sides of the motor...eh, hell...here is a picture:

The red is aluminum tubing

Oil cooling drawing.jpg (147.74 KiB) Viewed 307 times

My thoughts were that, if the fittings could be placed close enough to the periphery, perhaps some centrifugal circulation could take place bringing some of the oil out of the motor, into the greener thermal pastures of the aluminum tubing, maybe marginally decreasing some of the drag fechter mentioned, and have the added benefit of dumpng some of the cooler oil back across the motor while slowing and stopping. Who knows? If it works well, you could even start adding bends and fins to cool further.

It seems like some pretty readily available stuff, and fairly simple methods. What do you guys think? I am trying to decide if bucking the KISS rule is worth it.

If it turns out to be a complete failure, I could always call the holes... air vents

[fechter]

I don't think there would be any force to circulate the oil through the tubing. As the motor spins, centrifugal force on the oil would be balanced at both ends of the tubes. Heat transfer from the oil to the air throught the motor housing (aluminum) should be quite good. Adding fins to the outside of the housing would probably be more effective.

[GCinDC]

my hs3540 wire slot seal job lasted three weeks:

there were a couple 120C moments though rarely over 110, and some pretty hard hits, including yesterday, after which i noticed the rear brake losing grip...
can't wait to take it apart and see how it looks!

[ian.mich]

So what is the best oil to use? and on pretty much all hubs you have to replace the bearings correct? i'm using the pro 901 chinese hub kinda thing

[bigmoose]

Use a nice Automatic Transmission Fluid. Dextron III is a good choice. Anti oxidant, anti foam, thin, low viscosity. Don't over engineer this. We are not marketing STP or something that gives your engine eternal life...

[ian.mich]

Use a nice Automatic Transmission Fluid. Dextron III is a good choice. Anti oxidant, anti foam, thin, low viscosity. Don't over engineer this. We are not marketing STP or something that gives your engine eternal life...

Solid. Heard that name floating around. What about the bearings? should they go or stay
Thanks

[bigmoose]

Well I think you need to keep the bearings. I would use sealed 2 sides bearings and not shielded ones.

[Farfle]

Dual pie is aboit to get oil cooled, ill post up results between oil cooling and the johninCR style air cooling.

[ian.mich]

Well I think you need to keep the bearings. I would use sealed 2 sides bearings and not shielded ones.

well i meant would the bearings in the 901 need to be replaced, not removed completely lol. guess the answer is yes but ill have to have a look, i thing its safe to say they're shielded

[John in CR]

Dual pie is aboit to get oil cooled, ill post up results between oil cooling and the johninCR style air cooling.

I'd like to see these covers before you associate my name with it. interior blades? if so how oriented? Single side exhaust or dual side?...my approach evolves with each iteration and a 37°C motor at the top of a miles long climb will be hard to top.

How about a no-load speed, voltage, and current, sealed vs different amounts of oil fill ? ie very basic interesting and useful data still missing from this thread. The concept that only stator temp matters seems incomplete to me.

I look forward to your results. If there's climbing significant hills at speed involved for a significant average power it will be pretty lopsided, and not really even fair, since sealed with oil does have certain advantages over being open to the elements in wet and/or salty conditions. Mountains separate the men from the boys, just like in the TDF.

John

[ian.mich]

Are you sure that dexron iii would be good? wouldn't the oil eat through the shielding for the wires? i'm definately willing to shell out extra for a better oil

[GrayKard]

Well I think you need to keep the bearings.

Thanks, I needed a good laugh.

I'm considering oil cooling my next motor when I find the right one. I did an impulse buy off ebay recently of a hub motor but was pretty pissed off when I cracked it open and saw that the magnets are only 25mm wide in a 60mm wide magnet ring. Must be the low power version.

Gary

[ian.mich]

Well I think you need to keep the bearings.

Thanks, I needed a good laugh.

I'm considering oil cooling my next motor when I find the right one. I did an impulse buy off ebay recently of a hub motor but was pretty pissed off when I cracked it open and saw that the magnets are only 25mm wide in a 60mm wide magnet ring. Must be the low power version.

Gary

Talk to leo on skype leo840522 and he'll set you up with a 1000w hub and proper controllers, just replace the wiring with 10g enameled, put in shielded bearings, and oil cool and you can run some serious power

[GCinDC]

seal on the drive side finally leaked, after 4 weeks?

i'll pop it open this weekend and take lots of pics.

[zombiess]

If it weren't for all the leaking issues I'd love to give this a try, but I absolutely hate things that leak! If a hub motor was specifically designed to be liquid tight and contained wire which was oil safe I'd love to do this to smooth out the peak heat transients. I think my stepped drill bit is going to see some action again soon. I've been watching this thread hoping someone comes up with a great how to on sealing a motor that lasts longer than a few weeks.