Good! Someone finally oil cooled a hubbie!! HS3540

[parabellum]

Therefore, my question is why one would cover the windings with the special epoxy?

Maybe erosion? Remember, "water cuts trough rocks" give it time. It also holds windings and those funny sticks between tooth slots in place, I personally also like that varnish smell.

[dfar]

After about 1 month of riding the hub motor with ATF fluid I have been forced to open up the hub motor to repair the axle (nothing to do with the ATF fluid except that It maybe allowed me the widow to push this motor hard enough to fatigue the axle enough to break).

anyway when I opened it up there was still a lot ATF oil left inside, less than what I put in, but enough to cool the motor effectively but keep it from excessively dripping from the motor after use. I did not measure how much "optimal" oil was left (I still could I guess it's still in the container) but it looks to be a maximum 100ml. also it was noted that after the motor was dissembled ATF fluid was slowly draining (over the course of 2 days) out of the motor. I would assume this would be oil trapped between the stamped stator plates. if filling the motor up for the first time this would also have to be taken into consideration. This definitely helps the heat transfer.

I know you all want to know what the motor looked like so I'll get on with it. It was exactly as I had first purchased it, no rust, no degradation of the wire coatings in the wire or in the silicone phase/halls, the factory epoxy on the halls were unaffected.

so, so far so good. once I get my new axle I'll continue to test.

[hjns]

Cool, dfar! Thanks for the update. Pics look smooth, or should I say oily...

[parabellum]

anyway when I opened it up there was still a lot ATF oil left inside, less than what I put in

Where is most of your oil coming out? I am riding over 1 months (not everyday) and have a feeling I only lost few droops. Am I underestimating oil loses?
P.S. My MXUS has hole trough axle center not groove like yours. Thanks for your review and hope you fix it soon!

[John in CR]

I just ran across a warning about Neo magnets here http://www.mceproducts.com/knowledge-base/article/article-dtl.asp?id=2

"Do NOT use Neodymium Iron Boron magnets under the following conditions:

* In an acidic, alkaline, or organic solvent (unless you are going to hermetically seal the magnet inside a can)
* In water or oil (unless hermetically sealed, or you are prepared to accept a limited life)
* In an electrically conductive liquid, such as electrolyte containing water
* In a hydrogen-containing atmosphere, especially at elevated temperatures. Hydrogenation, a process where the Hydrogen molecule will react with the NdFeB, will occur, causing the magnet to rapidly deteriorate
* Environments containing corrosive gasses, such as Cl, NH3, Nox, etc.
* In the path of radioactive rays "

On all the motors I've opened, the nickle plating on the magnets is always scraped up or worse, so there's no way I'd consider them hermetically sealed.

[bigmoose]

John, have you considered all the magnets that are part of motorcycle alternators and have been bathed in engine oil, in fact hot engine oil,for their entire lifetime?

I sure hope you will stick with air cooling. This will give the rest of us time to surpass the performance of your monster motors!

John, I went and read your link in detail. The issue was with BONDED Iron Neo magnets that are held together with an organic binder I believe. Note how the headings and sub headings are indexed in the article you cited. This is not a problem with sintered Iron Neo magnets.

As we have all seen condensation will rust sintered Iron Neo magnets in a fortnight. Oil makes them look new for years. Join the revolution John...

[dfar]

anyway when I opened it up there was still a lot ATF oil left inside, less than what I put in

Where is most of your oil coming out? I am riding over 1 months (not everyday) and have a feeling I only lost few droops. Am I underestimating oil loses?
P.S. My MXUS has hole trough axle center not groove like yours. Thanks for your review and hope you fix it soon!

Well I lost more oil when I first filled it up (possibly With too much oil added) and by the end of a couple weeks of riding the amount that leaked was significantly less. The oil would leak out between the axle and bearing and then drip onto the rear freewheel which would then drip onto the tire which would then be thrown up towards my seat/back. When enough oil had been "naturally" drained out of the motor only enough oil to keep the chain/freewheel nicely lubricated would be evident, not even enough to cause drips and the max temps the motor could reach were still high 60's degree Celsius.

[John in CR]

I sure hope you will stick with air cooling. This will give the rest of us time to surpass the performance of your monster motors!

Bigmoose, I was just following a link in the technical section. I have no experience with motorcycle alternators, do they use neo mags? Also, no the indexing doesn't indicate the warning is just for bonded magnets, since it's the final part of the article and has a typeface equal to both the scintered and bonded sections. If you tell me it applies only to bonded, then I'll take your word for it, and send a note to MCE to correct their article.

I'm still trying to find a good reason to give oil a go rather than simply follow the crowd, since if I did that I'd have a mountain of burned up motors. I do need rain, mud, and beach bikes, so oil is attractive for that over a sealed motor.

The heat still needs to get transferred to air, and if it's done at the covers you're probably looking at well under 1kw in max heat rejection according to my calculated estimations. If you want to pass what my motors are doing using oil, then you'll need a radiator and a pump. The main motors I've used are barely more than the H35 in terms of stator size. It's the turn count and wheel size that makes them outperform what the vast majority use.

BTW, I only have one monster motor, and I just got it back on the road today with a controller that I hope will feed it, but Hubmonster has never been warm much less hot. That was when it was sealed, and now that it's ventilated it probably never will, at least not with a controller I can afford.

The new high efficiency motors I'm testing can't be oil filled without modification to give up their series/parallel shifting capacity, but their smaller outside shell makes them a poor candidate anyway. Those little motors definitely aren't monsters, and though they outclass typical ebike hubbies by a pretty wide margin in terms of build quality, design, and performance, they're too different to directly compare. Once I get around to ventilating one, I'll call it the MiniMonster in your honor, and it will most assuredly laugh at the oil drippers.

If you want to talk about design changes to include proper oil cooling that will result in a sub 20lb hubmotor that is economical and more powerful than can be accomplished with air cooling then I'm all ears. Until then let's see an oil filled hubbie running continuous at greater than 200wh/mile performance levels, because we're already hitting that and still haven't found the limit with an air cooled motor that could be called an HS40 if Xlyte made it. Don't forget Zombiess bike ran at 88wh/mile to win for the ebikes last week.

John

[Farfle]

I need to go thrash it around and get a screenshot, but the air cooled doublepie with my inexperienced 200 pound self has exceeded 200wh/mile average on the socal racetrack, it did overheat but not to the point of destruction, The temp sensor did pass 190C (thank you 220C rated wire ). BUT about 1KW of the heat its making is iron losses due to a construction error, so when I get in two more pies ill have to do another test.

[John in CR]

I need to go thrash it around and get a screenshot, but the air cooled doublepie with my inexperienced 200 pound self has exceeded 200wh/mile average on the socal racetrack, it did overheat but not to the point of destruction, The temp sensor did pass 190C (thank you 220C rated wire ). BUT about 1KW of the heat its making is iron losses due to a construction error, so when I get in two more pies ill have to do another test.

There you go BigMoose, another air cooled to try and surpass. To be fair I was talking about our 200mm stator 40mm wide motor.

Farfle, don't you have an extra pair of covers? I've got some ideas that should improve the air cooling fairly significantly over the current version. The fun you guys are having up there almost makes me want to move back stateside.

John

[whatever]

this is a bit off topic but.... if a hubmotor is getting hot and needs to be cooled, is it not better to rewind it to suit the power level being used? Would save alot of wasted energy

[Spicerack]

I need to go thrash it around and get a screenshot, but the air cooled doublepie with my inexperienced 200 pound self has exceeded 200wh/mile average on the socal racetrack, it did overheat but not to the point of destruction, The temp sensor did pass 190C (thank you 220C rated wire ). BUT about 1KW of the heat its making is iron losses due to a construction error, so when I get in two more pies ill have to do another test.

I know it's bit off topic...but... what was the construction error that led to the excess heat? Are the stator laminations shorted together or something?

[Miles]

this is a bit off topic but.... if a hubmotor is getting hot and needs to be cooled, is it not better to rewind it to suit the power level being used? Would save alot of wasted energy

Not sure what you mean? For a given torque output, copper losses will be the same, no matter how you wind it (assuming equal fill factor).

[Farfle]

I need to go thrash it around and get a screenshot, but the air cooled doublepie with my inexperienced 200 pound self has exceeded 200wh/mile average on the socal racetrack, it did overheat but not to the point of destruction, The temp sensor did pass 190C (thank you 220C rated wire ). BUT about 1KW of the heat its making is iron losses due to a construction error, so when I get in two more pies ill have to do another test.

I know it's bit off topic...but... what was the construction error that led to the excess heat? Are the stator laminations shorted together or something?

Yup, when the glue cured the two stators had rotated a very small amount relative to one another, so I couldn't fit the wire into the slot , so I took a skinny abrasive disk to the slot to open it up a small amount. which shorted all the iron together on the edges of the stator teeth.

[whatever]

Miles a hub motor is going to get hot if its overvolted, run within specs should be negligible heat.
Instead of cooling rewind for the amp/volts that are intended for it. Number of turns and thickness of wire are the main two variables, effect on torque I have no idea, but there should be some formulas out there to find out.

[hjns]

this is a bit off topic but.... if a hubmotor is getting hot and needs to be cooled, is it not better to rewind it to suit the power level being used? Would save alot of wasted energy

Not sure what you mean? For a given torque output, copper losses will be the same, no matter how you wind it (assuming equal fill factor).

Miles a hub motor is going to get hot if its overvolted, run within specs should be negligible heat.
Instead of cooling rewind for the amp/volts that are intended for it. Number of turns and thickness of wire are the main two variables, effect on torque I have no idea, but there should be some formulas out there to find out.

I think this is all completely true for motors that are being run within specs. If a motor is getting hot within specs, either the specs are wrong, or something else is wrong. And rewinding it would probably improve the specs, preventing the motor from getting hot.

However, feeding a HS motor >1kW can be considered out of specs. I think that there is a limit to the amount of rewinding that can be done due to the physical spatial limitations to fill the stator with more copper, regardless of amount of turns or size of copper wires. Therefore, cooling starts to become most important when you try to tease out the highest performance with a given stator and a given winding, where the variables are more "soft", e.g., battery voltage, battery current and phase current.

[Miles]

Miles a hub motor is going to get hot if its overvolted, run within specs should be negligible heat.
Instead of cooling rewind for the amp/volts that are intended for it. Number of turns and thickness of wire are the main two variables, effect on torque I have no idea, but there should be some formulas out there to find out.

Methinks you need to read up a bit more on motor theory......

Good resources to start with:
http://books.google.co.uk/books?id=gbID ... es&f=false

http://books.google.co.uk/books?id=lKs7 ... hi&f=false

[thepronghorn]

Miles a hub motor is going to get hot if its overvolted, run within specs should be negligible heat.
Instead of cooling rewind for the amp/volts that are intended for it. Number of turns and thickness of wire are the main two variables, effect on torque I have no idea, but there should be some formulas out there to find out.

Really? Really really? Miles knows exactly what he's talking about. He knows how hubmotors get hot, why they get hot, and how to prevent it. What we're talking about here is not running within specs, but running far beyond specs and still having the motor survive. The motors have already mostly maximized copper fill, so the only options for more power involve higher rpm/smaller wheels or better cooling.

[whatever]

As mentioned I have no idea how torque relates to rewinding a hub motor, my suggestion is not based on any thorough understanding of hub motor windings, you can take it more like a question if you like.
For example: lets say you take a x5304 ( older style) which I assume is wound for 48v 20-25amps to run within spec.
Then you overvolt and overamp it to get more speed and power ( torque ), would it not be possible ?? ( this is a question !)
to rewind it such that you could run it on say 100v and 60amps such that it wont overheat?????
Is this possible???

[Miles]

No, I'm afraid you can't gain anything by rewinding with a different turn count.

Terms like overvolt and overamp are a bit confusing and best avoided.

[whatever]

for noobs like me, found very nice site on hubmotor rewinds etc
http://www.avdweb.nl/solar-bike/hub-mot ... -variables

here is a very interesting idea for high effeciency at low rpm only winding each second stator
http://www.aerodesign.de/peter/2001/LRK ... o_eng.html

[parabellum]

here is a very interesting idea for high effeciency at low rpm only winding each second stator

Compromising a lot of things. Not very good for high power application and not usable in all motor designs.

[dfar]

posted the "plug/vent" system I'm using so far, working very well in combination with the ATF sealant and 100ml ATF fluid... no leaks yet!

viewtopic.php?f=2&t=37972&start=135#p572219

[hjns]

Hi dfar,

That is a huge plug. Doesn't it interfere with rotation of the motor?

[dfar]

Hi dfar,

That is a huge plug. Doesn't it interfere with rotation of the motor?

No it does not. It is placed on the disc brake side and drilled low enough that it misses the break caliper and wiring.

Good point though, one has to be certain that they have enough clearance with the brake calipers they are using. On my other motor I run regen braking so I don't use a back brake caliper so no worries about clearance there.