Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

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Ianhill   100 MW

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 19 2021 7:10am

I think motors of the future will keep the distance between copper and cooling loop to a minimum, the key in iron based motors will be to increase the contact area of the copper to water loop and lower the thermal resistance between the two.

One way of doing this fairly easy is in an inrunner motor, encapsulate the windings with a thermal potting then surround the stator with a water jacket.

Why do we see that as weak and keep pushing the envelope ?, Inrunners are decent but not the best utlization of space within a motor outrunners have a higher power denstiy even with thier lower rpm ranges, that tends to make them easier to gear down.

For example a skateboard outrunner can power a ebike at legal speeds and slightly beyond all in the size of your hand and not even watercooled.

Id like to see us all chip in together come up with a design we can all build, have the design in g code files or whatever the kids use these days and tske thst to you local metal shop and he can give you the bare components bsck for assembly, where i come unstuck is the laminations now there is a ferromagnetic 3d printing filament so we are edging closer and closer to this possibility soon.

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neptronix   100 GW

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 19 2021 1:09pm

A liquid cooled motor would be very expensive to design, produce prototypes for, figure out how to manufacture, find suppliers for, etc.. why do that when $5 worth of opticool could get you awfully close with an existing motor design?
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
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Ianhill   100 MW

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 19 2021 5:22pm

neptronix wrote:
Apr 19 2021 1:09pm
A liquid cooled motor would be very expensive to design, produce prototypes for, figure out how to manufacture, find suppliers for, etc.. why do that when $5 worth of opticool could get you awfully close with an existing motor design?
You would have to run a waste oil design like the early board track ICE bikes the ball bearings just wont hold oil like a crank unless you can fit a seal most motors i can think of would just leak like a teen on lager.

There is a design that springs to mind and i know i harp on about the dualtron hub motors but the shaft has a seal both sides on the shaft that may retain coolant plus being a hub motor the rpm even in a 100mph scooter wouldnt pass 2000rpm hoverboard motors are even better as they got the same seal on the shaft but only run one due to a mono type shaft or whatever it be called and they are the cheap way to test this theory.

What concerns me is the added mass if the fluid inside the motor and cavitation creating air bubbles and lowering the cooling capacity drastically if this negligible on a low enough rpm motor that runs high current you may just get a favourable outcome i wish you luck with the venture and try not to spray oil everywhere like a cathrine wheel lol.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by TDB » Apr 19 2021 11:09pm

neptronix wrote:
Apr 19 2021 1:09pm
A liquid cooled motor would be very expensive to design, produce prototypes for, figure out how to manufacture, find suppliers for, etc.. why do that when $5 worth of opticool could get you awfully close with an existing motor design?
Do you have shares in Opticool? :)

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by markz » Apr 19 2021 11:17pm

Ianhill wrote:
Apr 19 2021 7:10am
Inrunners
This was interesting when I came across it in the video
Geared Inrunner - https://youtu.be/c96n0Ma2rLY?t=818

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by john61ct » Apr 20 2021 12:53am


TDB wrote:Do you have shares in Opticool? :)
He's not claiming it would work, just cheerleading for people to try testing it


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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by JES » Apr 20 2021 1:05am

markz wrote:
Apr 19 2021 11:17pm
Ianhill wrote:
Apr 19 2021 7:10am
Inrunners
This was interesting when I came across it in the video
Geared Inrunner - https://youtu.be/c96n0Ma2rLY?t=818
A very interesting video. Wondering why a person couldn't fashion an air filter to cover the air flow ports in geared hubs , to keep the grit and grime out of the internals.?

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by TDB » Apr 20 2021 1:54am

john61ct wrote:
Apr 20 2021 12:53am
TDB wrote:Do you have shares in Opticool? :)
He's not claiming it would work, just cheerleading for people to try testing it
He could try testing it himself.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by markz » Apr 20 2021 2:36am

Yeah I dont know about venting a geared motor as all the dirt, grime and solids could chew up the gears. But it doesnt seem to be a problem with direct drive motors. People have tried lots of different methods from mini 12v fans glued inside the motor, to the metal holes having scoops to scoop more air into the motor, to atf, to custom ferro fluid, and who knows what else. If a motor is over heating, look into buying a beefier, heavier motor. Somewhere in those video's, at the end in the question period someone asks why not make an ultra large diameter motor, speaker stated there are no benefits.
JES wrote:
Apr 20 2021 1:05am
A very interesting video. Wondering why a person couldn't fashion an air filter to cover the air flow ports in geared hubs , to keep the grit and grime out of the internals.?

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 20 2021 7:25am

markz wrote:
Apr 19 2021 11:17pm
Ianhill wrote:
Apr 19 2021 7:10am
Inrunners
This was interesting when I came across it in the video
Geared Inrunner - https://youtu.be/c96n0Ma2rLY?t=818
That is an interesting find first of its type ive seen and thats becasue theres a strong reason.

I can not for the life of me really understand why they did that its not as efficent as a geared outrunner design so any of the cooling advantage with a direct connection to case is offset by having to overdrive the motor of same size compared to the outrunner design, it has a less favorable thermal path but more power dense design.

Grins new thru axle hub is a real nice design for low to meduim power rides its universal and pushes the bike frame to its capable limits anymore power than that and it becomes uncalled for on everyday roads specially if run as a pair on 72v thats more than capable of keeping up with all traffic but freeway/motorway and to me and the law pushbikes dont belong there.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by john61ct » Apr 20 2021 10:56am


Ianhill wrote:Grins new thru axle hub is a real nice design
This what you mean?
https://www.ebikes.ca/product-info/all- ... motor.html



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neptronix   100 GW

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 20 2021 11:28am

john61ct wrote:
Apr 20 2021 12:53am
TDB wrote:Do you have shares in Opticool? :)
He's not claiming it would work, just cheerleading for people to try testing it
No, i just have a particular interest in high energy density and efficiency motors. And see that people have been using ATF on this forum for a decade.. a fluid that is not compatible with all the materials inside our motors.
TDB wrote:
Apr 20 2021 1:54am
He could try testing it himself.
I would have already done it if i had a working ebike to test it with.
Ianhill wrote:
Apr 19 2021 5:22pm
What concerns me is the added mass if the fluid inside the motor and cavitation creating air bubbles and lowering the cooling capacity drastically if this negligible on a low enough rpm motor that runs high current you may just get a favourable outcome i wish you luck with the venture and try not to spray oil everywhere like a cathrine wheel lol.
Theoretical air bubbles lowering the capacity probably isn't too big of a deal when you're using a fluid with some of the best heat transfer characteristics.

It would be interesting to find a solution to the seal problem. Thermal expansion and contraction in hub motors is something that makes sealing them extremely difficult though. On a mid drive motor, where the shell is stationary, the sky is the limit though. You could seal the motor and add a crankcase breather filter like so to handle the expansion and contraction:

Image
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 20 2021 11:34am

Grin's thru axle motor has an extremely low mass of metal ( hence the exceptionally low weight ) and would benefit from some kind of oil fill and heatsinks extremely well. I haven't tried one since they do not have a rear motor version. The one notable efficiency booster in the motor is the N40 magnets.

What i would really like to see is a direct drive hub motor with 0.27mm laminations. It's possible that Grin could bring us this. I could not convince leafmotor to even remotely consider it.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 20 2021 12:10pm

john61ct wrote:
Apr 20 2021 10:56am
Ianhill wrote:Grins new thru axle hub is a real nice design
This what you mean?
https://www.ebikes.ca/product-info/all- ... motor.html
That be the one, only design i see this not working with is an upside down stantion forks but a 200mm travel ebike is deserves a centred mass and non pedal chain drive to be capable of serious jumping about.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by JES » Apr 20 2021 1:17pm

markz wrote:
Apr 20 2021 2:36am
Yeah I dont know about venting a geared motor as all the dirt, grime and solids could chew up the gears. But it doesnt seem to be a problem with direct drive motors.
A very interesting video. Wondering why a person couldn't fashion an air filter to cover the air flow ports in geared hubs , to keep the grit and grime out of the internals.?
[/quote]

That's the reason for the air filter. Air filters work for ICE which have even more high tolerance moving parts.
Simply porting a GHM on both sides, cover with a high grade auto air filter material (could even spray some oil on it to improve it's filtering capacity), and the spin of the casing would cause a transfer of air and heat out of the casing. seems like a simple solution.

If one wanted more air heat transfer, one could attach a trailing edge, small scoop on one side of the casings, inducing a positive air flow across the internals of the casings.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 20 2021 2:11pm

Justin proved that oil cooling is far superior to air cooling long ago. Air cooling only works well when you have oil cooling also.

The big challenge with geared hub motors is transferring heat to the case. They have exceptionally poor thermal transfer from the windings and magnets to the case as a rule. So air cooling them will help them less than a DD hub.

Filters for air cooling would slow the rate of entry and exit of air. Small amounts of gear grease may fling to them and block them, rendering them ineffective. if they got wet, you've got a problem there too.

We know that an oil fill has huge positive effects on geared motors but have not identified an oil that is compatible with the electrical components inside one of these motors. That's why ATF in the short term is great, but in the long term, seems to be a fail.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 20 2021 2:56pm

I see it as it must be a sealed system the outside contaminants will slowly make any fluid conductive.

I thought about it on a nasa level in my mind and the hamster wheel turned 30 seconds later a piece of paper popped out my pocket with the words dust is your conductive and possibly abrasive enemy.

I admire your will for more but i cant see how anything over statorade doses can benefit best you could find is an alternative and im sure i come across someone killing rc motors in oil and the improvement was noy there the kv had dropped massively from drag.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 20 2021 3:29pm

Excluding the special properties of ferrofluid, opticool is better at conducting heat as a fluid, and more of it can effectively be used per volume of motor. It also does not rely on transferring heat to magnets, which are sensitive to heat, therefore i suspect it's better at transferring heat overall, and should work in the geared and mid drive motors that statorade doesn't work well in:
Will this work in geared hub motors or mid-drive motor systems?
No, not really. Geared hub motors do not have their rotor shell exposed to ambient air, so increasing the heat conductivity from the motor stator to the rotor does not help get the heat to ambient air outside. Similarly, most mid-drive motors (like the Bafang BBSXX) are inrunners, where the magnets and rotor are on the inside and the heat generating stator, and conducting heat to them would serve no purpose. The benefits of Statorade are really only present for outrunner motors (magnets on the outside) where the rotor is exposed to air flow.
I am insistent on the trying the idea because all available data except for lubricity factors supports it's use in nearly any type of motor.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 20 2021 6:08pm

Id give you a hoverboard motor if you was in same country as me but what testing methods will you use to verify improvements.

Id say you need a vesc 6 and above a hoverboard and a dyno.

The dyno is easy enough for a simple size motor like this on a test a lever of a measured weight with a controlled weight can load the wheel through a skateboard wheel, like pulling down on a chop saw with more and more effort making the motor work harder and see whats going on through the vesc plus a thermal camera setup thats about as basic as i can come up with test a few motors to destruction without oil and with etc.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 20 2021 6:33pm

Easy to test for me.

I have an eZee in a 20" wheel that nobody wants, nor do i. I also have a thermal camera. I also live next to some insane prolonged hills. The eZee is not hard to get hot on them, lol.

No hoverboard needed. I'd like to sacrifice the motor in the name of science sometime soon, because i know this should tell me something about how this fluid would perform in a mid drive.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by HrKlev » Apr 21 2021 4:55am

If I can get tune the printed nylon gears for my g370 to work decently, I would have no problem with testing this. Getting any kind of transformer in my country in a smaller amount than 200 liter is difficult, though. Is there anywhere I can buy this in small amount online?
Hubdrive as middrive, with torque sensing EMTB build: viewtopic.php?f=6&t=107622

6x6 conversion: viewtopic.php?f=34&t=109567

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by TDB » Apr 21 2021 5:21pm

HrKlev wrote:
Apr 21 2021 4:55am
If I can get tune the printed nylon gears for my g370 to work decently, I would have no problem with testing this. Getting any kind of transformer in my country in a smaller amount than 200 liter is difficult, though. Is there anywhere I can buy this in small amount online?
It might be useful to put your location in your profile if you are going to ask questions like this.

I suggest not using transformer oil, paraffin (aka mineral oil), isoparaffin, opticool, spindle oil or silicone oil in a geared motor unless they are engineered for lubrication of bearings. You seem attuned to disassembling and working inside these motors. Try coating the stator and electrical bits before putting anything else in there. eg. ER2225 epoxy, MG4228, EL601.
Last edited by TDB on Apr 21 2021 8:22pm, edited 1 time in total.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by neptronix » Apr 21 2021 6:23pm

Yes actually, i wouldn't bother trying standard transformer oil. The problem is that it often has impurities which will eat into various types of materials inside a motor eventually. I don't know about paraffin based oils, but i do know that the isoparaffin/hydrotreated paraffin oil that's in opticool is a newer product of the petroleum industry, and is generally free of the petroleum-based impurities that eat at all sorts of materials over time.

You may not be able to find opticool in your country, but there are probably some other companies selling similar products based on hydrotreated/hydrocracked paraffin or isoparaffin oils that could work equally well.
I looked at a few but they weren't transparent about their ingredients, so i cannot be sure if there is something else like opticool or not.

The makers of opticool have targeted the electronics/computing industry mostly, and they have competitors in the electronics/computing market. So you may look for other suppliers that way.

Shell and Mobil at least do sell these heavily treated isoparaffins, so theoretically you could mix up something resembling opticool.. but maybe not a good job for a chemistry newbie.. :lol:
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?

Post by Ianhill » Apr 21 2021 7:16pm

Ive seen a raspi cooled submerged in a transparent liquid in a sandwich box i imagine that was opticool ?

Solid state pc cooling is something thats picked up interest the liquid is a much better interface than air.

One flaw i saw in the demo was the large gaps between any cooling stack and the circuit board making the liquid work overtime limiting its advantage.

In my eyes the best solution for solid state liquid cooling a pcb is to have a large heatsink the size of the board and the board stood off it with the thinnest layer of liquid that can get away with sepreating the too 1 or 2mm at most with a large enough alloy mass and surface area no fans required and closers this mass to the hest source the better and liquid being the best middle guy.

Thing is arm board is easy enough to cool with a decent heatpipe pc cooler and nothing else.

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