Oil cooling a motor with transformer oil/dielectric fluid - the next frontier?
- Thread starter neptronix
- Start date
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,871
john61ct said:
Justin used ferrofluid to complete a thermal bridge to case its principles are completely different its a very small amount held in magnetic suspension.
Just to add justin shows also thats theres a detrimental effect by overdosing a motor so its clear to me this idea is as bad as pissing in a tornado.
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,871
Heres a good analogy,
how far and fast do you think you could run with 30c air all around you.
How far and fast do you think you could run with 30c water all around you.
I know when im in water my movement is slowed drastically i can feel the drag all around me and my heat dissapation barely improves i still fell hot and will get tired.
But if you jump in the artic you will soon know about it when your heart stops thats conductive cooling for you, best bet is get water suppky in and out with the centre spider turned into a cooling plate the flow is reverse meaning the hest has to travel inwards not naturally best but its better than filling it up and hoping for the best lol.
Temperature differential is key.
how far and fast do you think you could run with 30c air all around you.
How far and fast do you think you could run with 30c water all around you.
I know when im in water my movement is slowed drastically i can feel the drag all around me and my heat dissapation barely improves i still fell hot and will get tired.
But if you jump in the artic you will soon know about it when your heart stops thats conductive cooling for you, best bet is get water suppky in and out with the centre spider turned into a cooling plate the flow is reverse meaning the hest has to travel inwards not naturally best but its better than filling it up and hoping for the best lol.
Temperature differential is key.
sleepy_tired
100 W
- Joined
- Jul 2, 2019
- Messages
- 185
That is exactly what is being discussed here.
It all cases vehicle motors, except boats, are ultimately air cooled. If they use liquid cooling, water or oil or whatever, then the goal is to use the coolant to move the heat from the motor to a external heatsink to where it can be shed into the atmosphere.
In the case of hub motors, which are are 'outrunner motors'... that external heatsink is the external shell. Hub motors have their internal copper windings physically separated from the external shell. The default liquid is air. So hubs need to transfer heat to the air inside the shell and then from the shell into atmosphere.
Ferrofluid is 100% legit "oil cooling". Due to the magnetic properties of the fluid it stays put. Which is why you don't need a lot of it. It forms a physical bridge, made of oil, from the hot copper windings to the external shell because the magnets are glued to the shell.
Grease works in a similar way. It stays put so you don't need a lot of it. The actual lubrication in the grease is oil, just the same as any other oil. It's just held in a matrix, like lithium soap in the case of lithium grease, that makes it 'sticky', but shears away under any sort of pressure leaving just oil to do the actual lubrication. This is why grease works so well with bearings. Packed bearings may 'feel' sluggish, but when they are under pressure they are actually oil lubricated.
However in geared hubs ferrofluid doesn't work. Because there is no strong lines of magnetic force between the motor and the external shell.
So if you want to cool a geared hub motor you need to have enough oil to physically displace the air in the motor and form a physical bridgel. Otherwise it works in exactly the same way as ferrofluid.
Yes this will lead to noticeable friction losses, but the benefits can easily outweigh the downsides power-wise.
However we know from ferrofluid and people using ATF in the past that it can 100% work.
That being said...
I don't see the point to having oil cooling setup for mid-drives on a ebike. Because you can use a inrunner motor. With a inrunner motor the copper windings are heatsink'd directly into the external shell. If you need additional cooling you can add fins or wrap the motor in copper tubing or something like that and use some metallic epoxy to physically join things. You can also vent the copper windings directly to atmosphere. Dust and crap won't hurt those motors because the bearings are sealed. Same reason car alternators can last for hundreds of thousands of miles.
Ianhill said:
Yes, exactly. Put your hand on a geared hub motor without ATF, and 80C in the windings, then do the same with ATF. With the ATF, the case gets hot, letting the motor dump some heat to the surroundings.
You should read the thread where Justin tests oil in a dual reduction geared hub motor, if you havent.
A-DamW
100 W
I wonder what kind of motor cooling fluid is used in the Tesla and other ev's?
sleepy_tired
100 W
- Joined
- Jul 2, 2019
- Messages
- 185
Engine coolant. Ethylene glycol and water mixture. Normal stuff, but the better quality stuff.
The coolant doesn't come into contact with any electronics. It all flows through plastic/metal motor housing.
https://www.valvoline.com/our-products/heavy-duty/zerex-g-48
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,871
HrKlev said:
Ill be honest with you i only seen the dd ferrofluid results and the geared hub ive had a grand total of none avoiding them like the plague due to heat restraints but id love to see a test of 3 motors one stock for a yard stick then a well vented air cooled motor vs the fluid and see which one is chooching last feed them till they die faced off in a load scenario i got my money on the air that wins no need to explain the air stays at 30c been sucked in the motor but the fluid warms and keeps the heat in contact so actual acts as a blanket in the end but i guess thats just a theory that 800w motor could answer.
sleepy_tired
100 W
- Joined
- Jul 2, 2019
- Messages
- 185
If your goal is to have a reliable transportation with electric bicycles then DD hub motor with ferrofluid is best option. Add thermal monitoring and it's effectively bullet proof. Everything else is buggy and over-complicated in comparison.
If people can find a similar solution for geared hub motors then that will be fantastic advancement.
I am sure you can find some cooling testing during the development of 'statorade' and dozens of other people's experiments if you search the forums.
If people can find a similar solution for geared hub motors then that will be fantastic advancement.
I am sure you can find some cooling testing during the development of 'statorade' and dozens of other people's experiments if you search the forums.
sleepy_tired said:
Problem scenarios for that:
Getting the bike up a set of stairs is now much more of a fitness challenge.
Changing an 18lb wheel and having to knock it out of the dropouts on the side of the road and manhandle the wheel is a pain in the ass.
Big negative impact to rear suspension from the extra unsprung weight.
Don't get me wrong, i love DDs. But they aren't the end all solution for everyone.
My first electric bike was a DIY friction drive that was easily detachable.
At the time, I lived in a second-story apartment, and I had no room for the bike, which was locked up outside.
Roughly 1,000W and 20-MPH...
At the time, I lived in a second-story apartment, and I had no room for the bike, which was locked up outside.
Roughly 1,000W and 20-MPH...
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,871
Id rather not have rear suspension with a hub motor it becomes like a delayed bucking bronco if the swingarm is of the longer variety.
I had an a2b metro and thats got a comically large back swing arm that likes to crack its such a lever, add a mxus 3k in there and i felt like a horse jockey over any rythem sections, but on the flat never have i riden such a relaxing ride very calming and swallowed a curb up like its not there just dont ask the suspension to do it again in short succession.
Nice hardtail with a 1000w or so hub is more than enough of a communter ride for most to make a simple as can be diy build, tyre choice is key to success like mentioned fixing a flat is no joke and some tyres are paper thin i got agressive downhill tyres that will be a no go for the road get like 3 punchers a week with them they shit on tarmac but excellent in the bog, horses for courses you got to learn a bit as you go to realise what suits your riding best, plus your strength and house access dictates the final ride how much you need to life and to where etc.
Thats the only reason ive not built a road bike i got little access but to leave it chained to fence for all to strip what they want so i keep my rides under 50kg so i can man handle it about if i need to but obviously i dont live in a new york high rise apartment or id be stuck to 36v foldable commuters and trying to push that to its safe limits.
I had an a2b metro and thats got a comically large back swing arm that likes to crack its such a lever, add a mxus 3k in there and i felt like a horse jockey over any rythem sections, but on the flat never have i riden such a relaxing ride very calming and swallowed a curb up like its not there just dont ask the suspension to do it again in short succession.
Nice hardtail with a 1000w or so hub is more than enough of a communter ride for most to make a simple as can be diy build, tyre choice is key to success like mentioned fixing a flat is no joke and some tyres are paper thin i got agressive downhill tyres that will be a no go for the road get like 3 punchers a week with them they shit on tarmac but excellent in the bog, horses for courses you got to learn a bit as you go to realise what suits your riding best, plus your strength and house access dictates the final ride how much you need to life and to where etc.
Thats the only reason ive not built a road bike i got little access but to leave it chained to fence for all to strip what they want so i keep my rides under 50kg so i can man handle it about if i need to but obviously i dont live in a new york high rise apartment or id be stuck to 36v foldable commuters and trying to push that to its safe limits.
Ianhill said:
I lol'd at 'rhythym sections'.
I had an a2b metro for a minute and know exactly what you're talking about.
Before i found the leafmotor 1.5kw, i ran a BBS02 in a Turner O2 ( very light, expensive downhill bike, great suspension travel ). The offroad action was fantastic - a straight up joy. The bike glided along broken pavement on the street, too.
Then i put on a 16lbs leafmotor and the suspension became 'just adequate' for my broken roads. It performed like it had a low quality, short travel spring suspension, and no amount of tuning the shocks helped much. And offroad riding quickly became something i didn't want to do.
This problem is made even worse for me due to the requirement for a heavy motorcycle tire in the rear so that i can avoid constant flat tires out here in goathead hell. Any bike i build has +3lbs of unsprung mass before we even start talking about the motor.
This leads us to circle back to exploring mid drives and AWD geared motor setups if we need/want good suspension performance. Then exploring exotic cooling solutions like opticool and some other products mentioned ( as long as they have certifiably good materials compatibility. ) so that we can crank up the power density of a tiny motor and get away with it.
The big reason transformer oils are not used in electric motors is viscosity plus some are pretty toxic.
FWIW, I used distilled water in my MAC motor to keep it cool with a little Motul MoCool as a corrosion inhibitor.
I also tried low viscosity ATF and it worked great until a little leaked on my brake rotor which made my rear brakes useless.
It is going to be tough to find something with a lower viscosity than water as well as the heat carrying capacity of water. The low viscosity ATF was very thin i.e. low viscosity. With both water and ATF being readily available and inexpensive as well.
If you can contain it, I'd use low viscosity ATF...it lubricates, cools, and you can buy it for a couple bucks at Walmart.
Although I ran the distilled water/MoCool mixture for about six months without any issues but water may not work in all motors.
FWIW, I used distilled water in my MAC motor to keep it cool with a little Motul MoCool as a corrosion inhibitor.
I also tried low viscosity ATF and it worked great until a little leaked on my brake rotor which made my rear brakes useless.
It is going to be tough to find something with a lower viscosity than water as well as the heat carrying capacity of water. The low viscosity ATF was very thin i.e. low viscosity. With both water and ATF being readily available and inexpensive as well.
If you can contain it, I'd use low viscosity ATF...it lubricates, cools, and you can buy it for a couple bucks at Walmart.
Although I ran the distilled water/MoCool mixture for about six months without any issues but water may not work in all motors.
mcfizzlestag
10 mW
- Joined
- Apr 23, 2018
- Messages
- 29
I was going to give this a try, but i was only able to find some old polychlorinated biphenyl based transformer oil that was hidden in the back of a seacan. The newer stuff we use in our 69kv-12kv transformers was sealed away in unopened containers :/ They last changed the oil when i was on vacation
DaLanMan
10 kW
I know it is gonna sound weird but...
My mum in law worked for SoCal Edison, she has volunteered to call the yard and see if there is anything they would recommend that won't be you driving around town on cancer goo...
Yeah, mum in law climbed poles and stuff, she is cool.
My mum in law worked for SoCal Edison, she has volunteered to call the yard and see if there is anything they would recommend that won't be you driving around town on cancer goo...
Yeah, mum in law climbed poles and stuff, she is cool.
Sweeet...standing by for info.
DaLanMan
10 kW
I wouldn't be surprised I would venture a guess that Edison has probably dealt with more cooling fluids than any other company besides potentially the manufacturer. It only stuck in my mind because of the detailed info that my mum in law had about the stuff in the first place, In my BioChemist brain it was labeled as "cooling oils, most often very carcinogenic" and that is about where i stopped really even thinking about it.
So, printed out the info sheet from earlier in the thread and will deliver it to the mum in law so she can natter with her buds in SoCal about the topic. The good news is, these are all retired folk who are fairly bored, so there will be an answer.. it will probably be a wall of text at some level
More when I have it.
So, printed out the info sheet from earlier in the thread and will deliver it to the mum in law so she can natter with her buds in SoCal about the topic. The good news is, these are all retired folk who are fairly bored, so there will be an answer.. it will probably be a wall of text at some level
More when I have it.
I'm sure they have a great choice for their specific application.. which is similar to a motor, but not exactly.
What we need is a fluid with a very high materials compatibility, one that doesn't eat petroleum-based plastics, nylon gears, circuit boards, circuit board traces, electronic components, etc.
It's not hard to find a good fluid to cool a transformer. it's extremely hard to find fluids compatible with a super wide range of materials though.
I'm all ears if you come up with a suggestion that has a provable super wide range of materials compatibility.
What we need is a fluid with a very high materials compatibility, one that doesn't eat petroleum-based plastics, nylon gears, circuit boards, circuit board traces, electronic components, etc.
It's not hard to find a good fluid to cool a transformer. it's extremely hard to find fluids compatible with a super wide range of materials though.
I'm all ears if you come up with a suggestion that has a provable super wide range of materials compatibility.
And with the right viscosity and other fluid properties.
Doesn't exist unless there's some exotic ATF i don't know about.
DaLanMan
10 kW
I still think standard food grade mineral oil is the better solution. I used to do test systems (where we literally had a CPU and no chiller design) by plunking the whole thing in a fishtank of the stuff. It worked fine, one of the guys got nutty one afternoon and we built him a clear lexan case, off he went 5g of oil in a tub, computer in a fishtank, it ran for some years like that.
In the lapridary world we cut rocks, at home, with ginormous saws (I have seen a 48" bad boy) and yep, flood it with Mineral oil. there is even a company that makes a de-funkifier additive (extends the time til it goes off) and a cleaner (well, mebbe not useful on an ebike, but rocks spew a lot of stuff when ya lop em up.
I will ask, i am fair certain one of the nutty jockos had some idea about cooling something with the stuff, these are the guys that ran a warming system for a hot tub off a big mains transformer that "happened" to be in their back yard back in the day.
It's endemic, put moderately intelligent individuals, mind you like 90% college edumacated together with things that can go boom, and there ya have it, the transformation of money into noise and smoke
In the lapridary world we cut rocks, at home, with ginormous saws (I have seen a 48" bad boy) and yep, flood it with Mineral oil. there is even a company that makes a de-funkifier additive (extends the time til it goes off) and a cleaner (well, mebbe not useful on an ebike, but rocks spew a lot of stuff when ya lop em up.
I will ask, i am fair certain one of the nutty jockos had some idea about cooling something with the stuff, these are the guys that ran a warming system for a hot tub off a big mains transformer that "happened" to be in their back yard back in the day.
It's endemic, put moderately intelligent individuals, mind you like 90% college edumacated together with things that can go boom, and there ya have it, the transformation of money into noise and smoke
