Oil cooling your hub- NOT snake oil!

[izeman]

so good things first: removing the cover was easier than i thought. the side cover was sealed to be leak proof. 3 arm gear puller, a little "plop" and the cover was removed. inside everything was shiny, and nothing was broken because of the oil. heat shrink looked like new, metal epoxy on the thermistor - like new. so no problem.
the problem though is the oil itself. i creeps through the tiniest holes. not fast, but slowly. these motors where just not designed to hold any fluid for a long time. as i hate car motors that leak oil, i hate ebike motors leaking oil even more. i thought it could be a fill one, forget forever thing, but that's not true. it did work REALLY great. i never reached temp above 110°C at the windings. perfect.
but the mess you have when you need to service the motor isn't worth it.
so i may think about air cooling. i hope it's not too late, as i have no idea how to remove all the oil from the stator to paint it with anti rust paint. i think i will have to bath it in solvent and do this several times. any ideas?

here are some pictures:

60A may have been to much for one of the 4mm goldies. it must have been very hot, melting the plastic arount it. it's black inside. those connectors are not very good. first time use they are a tight fit and become more and more lose every time you reconnect them

50ml of oil came out of the motor. as i put 120ml in, there must be some 50-70ml left inside, as only some drops leaked over time.

oil everywhere

looking like new

 

[izeman]

i forgot to mention: oil was even creeping between the bearing and the case!! so this is not a very tight fit at all.

 

[neptronix]

Run two 4mm bullets in parallel for each phase. That's what i do for my higher power motors and controllers.

4mm bullets are rated at 90a i think. I'm sure that's a peak figure and not a continuous one.

 

[teklektik]

...
so i may think about air cooling. i hope it's not too late, as i have no idea how to remove all the oil from the stator to paint it with anti rust paint. i think i will have to bath it in solvent and do this several times. any ideas?

I would clean it with either or both of:

• an aerosol Mass Air Flow sensor cleaner - (kind of like a wussy spray brake cleaner that is safe for plastics) - this will cut the oil but won't compromise any of the synthetic components (insulation, etc)
• washdowns with spray-on Simple Green Concentrate (dark green - auto stores, Home Depot, etc) - I use SGreen to de-grease engine parts (actually - just about everything)- cheap, remarkably effective, no nasty solvents, and biodegradable. Rinse well and let dry.

 

[amberwolf]

wouldn't just leaving hte oil on all the internals keep the water from rusting it?

 

[izeman]

wouldn't just leaving hte oil on all the internals keep the water from rusting it?

probably yes, for some time. but oil has the bad habit to adhere to dust, sand and other debris. so sooner or later you have some sticky mass in your motor i'm afraid. and the oil probably won't cover all of the stator for a long time. if you spray some mos2 film on your tools, or what ever you want to protect it someday will be gone as well if left in the rain it can happen within weeks.

 

[speedmd]

Warm water / hand Dish soap and follow with Alcohol to get the remaining traces of oil - grease films off. Standard procedure in prep for paint or adhesive application.

 

[izeman]

Warm water / hand Dish soap and follow with Alcohol to get the remaining traces of oil - grease films off. Standard procedure in prep for paint or adhesive application.

but this won't remove the oil inside the stator?!

 

[speedmd]

Detergent and warm water will take most of the oil away. Best first step unless you still have access to one of the vapor type de greaser. Depending on how deep the stuff is hidden it may need to soak for some time, so plan on taking off the bearings or repacking them ASAP.

No matter what you use the first step, it will most likely leave a mild oil film and oil will most likely creep out of the tiny slots crevices indefinitely with heat cycles. For the remaining film, the alcohol dip / mild bake dry, works good enough to allow most paint and glues to stick very well.

 

[amberwolf]

probably yes, for some time. but oil has the bad habit to adhere to dust, sand and other debris. so sooner or later you have some sticky mass in your motor i'm afraid.

Doh--of course! I guess I'm just stupid this week. :lol:

 

[The Stig]

probably yes, for some time. but oil has the bad habit to adhere to dust, sand and other debris. so sooner or later you have some sticky mass in your motor i'm afraid.

Doh--of course! I guess I'm just stupid this week. :lol:

Well I dunno... could be better than rust. Like if you're going close to salt water any time soon.



BTW people, when using brake cleaner should I be worried about getting it on the insulation around my phase wires? Like the black insulation, but also the insulation around the actual phase wires is exposed in one place...

 

[izeman]

BTW people, when using brake cleaner should I be worried about getting it on the insulation around my phase wires? Like the black insulation, but also the insulation around the actual phase wires is exposed in one place...

definately YES. of course as always it depends on the insulation and it depends on the brake cleaner some are more aggressive, and some cheap chinese heat shrink my dissolve.
btw: i found that some of the heat shrink i used some kind of started to dissolve i can't tell if it was because of heat or if i was because of the oil. the phase wire's ones where all intact, but the little tiny ones covering the hall contacts, almost fell apart. not that big deal as the wires are buried in metal epoxy which is isolating, but not nice.

 

[teklektik]

BTW people, when using brake cleaner should I be worried about getting it on the insulation around my phase wires?

...the reason for the suggestion to instead use MAF Cleaner and Simple Green detergent...

 

[crossbreak]

you could test your brake cleaner at the star point where insulation is not necessary.

BTW I use 5.5mm bullets with success (12s Lipo, 85amps, 24Fets), but plugged them not very often. After my first XT60 melted together and I had to cut the wire I got more careful. I use only 2/3rd of the rated current for my all of my plugs.

 

[izeman]

yesterday i replaced the bearings of my hs3540, and decided to try the motor w/o oil for a test ride. 60A@80V and a steep hill. at the end it was at about 85°C. rode some more, and switched to 2500w max and 1500w with pas only. temp was at 105°C max, and slowly climbing.
with oil it was 70°C and not going over 90°C. but i will test with oil tomorrow when the whole motor has cooled down again.
i hope it will not leak anymore

 

[GCinDC]

i hope it will not leak anymore

it will definitely leak again unless you seal it to death. IIRC, you didn't use any sealant at all the first time, right? use brake cleaner on the stator only to get it dry, and don't let it touch the windings. sealt the wire hole, around the bearing - it will still work - and then of course around the side covers. test ride it for a while before installing new brake pads - oh yeah, clean those with brake cleaner too - it's what its for!

if it leaks again, get out your drill.

 

[izeman]

i hope it will not leak anymore

it will definitely leak again unless you seal it to death. IIRC, you didn't use any sealant at all the first time, right? use brake cleaner on the stator only to get it dry, and don't let it touch the windings. sealt the wire hole, around the bearing - it will still work - and then of course around the side covers. test ride it for a while before installing new brake pads - oh yeah, clean those with brake cleaner too - it's what its for!

if it leaks again, get out your drill.

of course i sealed it lol! it's all in my thread. sealed the cables with heat resistant silicone, sealed the covers, sealed the cable slot. but i didn't swap the bearings. when the first drop of oil appeared on the disc side it was grey/black. like it washed out the grease from the bearings. so i installed double sealed skf bearings, and went through all the sealing again. and of course it used break cleaner to remove grease, oil and old silicone before i did the sealing again. but as you said: if it's gonna leak now i will drill some holes.

 

[Electric Junk]

what would be better to use in a gear hub motor, air tool oil or ATF?

 

[izeman]

oh man. i hate it! took me hours to seal the hub. bought high heat silicone, brake cleaner etc ...
now with 75ml in the hub it started to leak. was fine with 45ml. but maybe it would have leaked after some time again. i have only done 40km since i sealed it.
i guess i will have to switch to air cooling. i HATE oil coming out of an electric motor!

 

[GCinDC]

oh man. i hate it! took me hours to seal the hub. bought high heat silicone, brake cleaner etc ...
now with 75ml in the hub it started to leak. was fine with 45ml. but maybe it would have leaked after some time again. i have only done 40km since i sealed it.
i guess i will have to switch to air cooling. i HATE oil coming out of an electric motor!

Leaking out of the bearing again? Sorry to hear that.

 

[izeman]

yep. bearing, cable slot, ... whatever. i can't see where it comes from. could be it's slipping "around" the bearing. the seat is not 100% tight. i had to use some loctite to fix the bearing.
however. another new set of brake pads is f*cked up after 20km only.
if i only knew what would be the best cooling hole pattern for (forced) air cooling. maybe i'll make a visit at my old university and ask some of the guys at the institute of fluid mechanics if they have some ideas.
once you smell the power of 4kw+ you will not be happy with 2kw. won't image what i would do with a bigger controller than my small little (but heavily modded lyen 12fet)

 

[speedmd]

Hi Izeman

Ask if any at the U. have a heat flow program for solid works or other modeling program. Time we model a common motor. Many "Mold flow" programs will also do a heat flow analysis as it is critical to a plastic part setting up time in a mold which is directly related to part quality, cycle time / cost.

We can then play with a host of venting scenarios in a fraction of the time and cost.

 

[bowlofsalad]

I was posting in someones thread http://endless-sphere.com/forums/viewtopic.php?f=31&t=51853 about water cooling and other cooling techniques for electric motors. I have spent some time pondering the options available when it dawned upon me that what may be an excellent addition to oil cooling is gluing (thermal glue), soldering, brazing or otherwise attaching a pair (for balance) of heatsinks to the side 'top' of a motor.

Has this been tried? Did it work?

Originally I was thinking of attaching a pair of fan blades or something similar to the side of the motor just to increase the air flow over the surface, this is probably something commonly done when people drill holes in their motor cover, but I imagine it might work or help to cool even with a smooth surface.

 

[Sancho's Horse]

It works.

 

[The Stig]

I was posting in someones thread http://endless-sphere.com/forums/viewtopic.php?f=31&t=51853 about water cooling and other cooling techniques for electric motors. I have spent some time pondering the options available when it dawned upon me that what may be an excellent addition to oil cooling is gluing (thermal glue), soldering, brazing or otherwise attaching a pair (for balance) of heatsinks to the side 'top' of a motor.

Has this been tried? Did it work?

Originally I was thinking of attaching a pair of fan blades or something similar to the side of the motor just to increase the air flow over the surface, this is probably something commonly done when people drill holes in their motor cover, but I imagine it might work or help to cool even with a smooth surface.

What kind of salad are you?