Definitive Tests on the Heating and Cooling of Hub Motors

[macribs]

CD do you dare inject 5 ml of FF in that leaf? Wonder if the fans would work with FF to lower the max temp as you are showing similar max temp w/wo them fans running.
If FF could be used in conjunction with your fans/vented side covers that should really give you the best of both worlds? Lower max temp, yet rapid cooling ie in a red light WOT-stop-WOT situation or steep hill climbs without the need to stop for cooling.

 

[Cowardlyduck]

CD do you dare inject 5 ml of FF in that leaf? Wonder if the fans would work with FF to lower the max temp as you are showing similar max temp w/wo them fans running. <br abp="681">If FF could be used in conjunction with your fans/vented side covers that should really give you the best of both worlds? Lower max temp, yet rapid cooling ie in a red light WOT-stop-WOT situation or steep hill climbs without the need to stop for cooling.

Yikes! That ain't happening...not unless someone else wants to throw me the money to cover a destroyed hub.
I agree, it would be the best of both worlds and probably provide fantastic cooling....for a while, but as Justin and others pointed out, the FF would soon become full of grit and turn to a sort of paste.
For sure in a drag racing, or racing setup, combining fan cooling and FF would be awesome, but not for anything you expect to last.

Cheers

 

[macribs]

Hm yeah you are right, FF would be cruel and unusual punishment for your leaf.
And your numbers shows how fast it cools down the motor, impressive from those tiny blowers. Did you alter the number of fans? Seems to remember a pic of your hub with only half the number of fans? Or could be my brain is acting up

I remember there was talk earlier in the thread about using some artificial membrane that work in a similar way a Gore Tex and other breathable's.
Wonder if there is some industrial strength membrane that could let the heat out while blocking for debris, sand and grits that would pollute the FF?


Gonne Googling

 

[macribs]

Where would be the best place to drill the side cover for injection of Ferrofluid? Left side close to bearing or closer to the windings?

What kind of flat black paint to get? I see some got some red paint (rust protect??) to shield the internals, then krylon ultra flat black on the side covers. Others has gone for flat black over all of the internals. Krylon ultra flat black was mentioned earlier - but is krylon tested and compared to other flat black paint regarding what drops the temperature the most ?

I used Sprayon emal rust protection on every of my hub motor and never experienced any problem with them.

Will any flat black do, or is there some that might work better then other? Remember I will be using ferrofluid also.

Docbass's mxus with rust protection:

As you can see also the magnets are painted:

Covardlyduck's flat black side covers:

Paint the inside of your covers flat black. It will make a huge difference in a sealed motor. The worst thing you could do is have shiny aluminum covers in a sealed motor. The difference is larger than you imagine as the thermal radiation bounces back and forth. You can see a 20+ C drop doing this simple mod on a sealed motor.

Don't paint the magnets. You don't want them absorbing heat. Shiny nickel plating is good here.

Don't paint the winding. Pot them in a material with high thermal conductivity to prevent hot spots such as SC-32

So don't do like docbass? Use SC 32 on winding? I live by the sea with salty humid air, and plenty of salt drizzled over the roads in the winter. So I really need to protect the motor from the harsh environment, what to choose?

 

[madin88]

Where would be the best place to drill the side cover for injection of Ferrofluid? Left side close to bearing or closer to the windings?

as most motors do not come sealed, i would open it and apply it directly on the magnets. than truly seal it up.

Justin, i know it may be a bit to early to ask, but could you notice a difference between the synthetic and ester based Statorade, or what variant would you recommend?

 

[Joe90]

Justin is doing a lot of work for the love of it.

I would like him to continu doing soo.

Justin you should have a donation button somewhere ?

I would like to make a small donation to say THANKS !

 

[MrDude_1]

Justin is doing a lot of work for the love of it.

I would like him to continu doing soo.

Justin you should have a donation button somewhere ?

I would like to make a small donation to say THANKS !

he has a nice shop. ( http://ebikes.ca/ ) Buy your stuff from there (and dont be a pain in the ass customer) and he'll appreciate it. I buy stuff from there, but I am still working on the "not being a pain in the ass" part.

 

[John in CR]

Justin,

What's the most time or mileage you've run FF in a motor? My only concern about running FF is the life of it. I don't want to have to tear a motor down a year from now to clean up FF that's gummed up. I know your tests can run pretty long, but have any added up to a week or more of continuous use? If not, can you hook up your highest rpm hubbie, add FF and let it run at WOT continuously for a week or 2. If you don't see a change over that kind of time frame it sure would put my mind at ease about trying it in one of my more expensive hubbies.

 

[MrDude_1]

Justin,

What's the most time or mileage you've run FF in a motor? My only concern about running FF is the life of it. I don't want to have to tear a motor down a year from now to clean up FF that's gummed up. I know your tests can run pretty long, but have any added up to a week or more of continuous use? If not, can you hook up your highest rpm hubbie, add FF and let it run at WOT continuously for a week or 2. If you don't see a change over that kind of time frame it sure would put my mind at ease about trying it in one of my more expensive hubbies.

I have a side question...
if you get FF on permanent magnets, how DO you get it off? will it dissolve in brake cleaner or acetone? what washes it off or breaks it down?

 

[macribs]

Justin,

What's the most time or mileage you've run FF in a motor? My only concern about running FF is the life of it. I don't want to have to tear a motor down a year from now to clean up FF that's gummed up. I know your tests can run pretty long, but have any added up to a week or more of continuous use? If not, can you hook up your highest rpm hubbie, add FF and let it run at WOT continuously for a week or 2. If you don't see a change over that kind of time frame it sure would put my mind at ease about trying it in one of my more expensive hubbies.

I have a side question...
if you get FF on permanent magnets, how DO you get it off? will it dissolve in brake cleaner or acetone? what washes it off or breaks it down?

I would not try to break it down, as the ferro particles would stick even if you dissolve the fluid part.
Just get yourself a much stronger magnet and the FF should transfer nice and easy.

 

[John in CR]

Justin,

What's the most time or mileage you've run FF in a motor? My only concern about running FF is the life of it. I don't want to have to tear a motor down a year from now to clean up FF that's gummed up. I know your tests can run pretty long, but have any added up to a week or more of continuous use? If not, can you hook up your highest rpm hubbie, add FF and let it run at WOT continuously for a week or 2. If you don't see a change over that kind of time frame it sure would put my mind at ease about trying it in one of my more expensive hubbies.

I have a side question...
if you get FF on permanent magnets, how DO you get it off? will it dissolve in brake cleaner or acetone? what washes it off or breaks it down?

I would not try to break it down, as the ferro particles would stick even if you might dissolve the fluid part.
Just get yourself a much stronger magnet and the FF should transfer nice and easy.

I can guarantee that's easier said than done. Hopefully it's not too much harder than getting iron dust and shavings out.

 

[speedmd]

Rubbing alcohol is commonly used to remove oil residue which should get to the FF base reasonably well. WD40 or kerosene should make it more liquid enough to mop up in a rag also in a pinch. Like the strong magnet idea also for the magnetic residue.

 

[Kodin]

Stronger magnet works, but keep in mind these are strong magnets anyway; watch your fingers and wear safety goggles when you do it in case the magents crash together; I've seen magnets "stick" hard enough to shatter and send shards flying. I'd start with a cotton rag, and one that you don't mind being permanently stained at that. (Don't use your girlfriend's towel).

 

[John in CR]

Apparently you guys haven't had to remove iron dust from a hubbie. FF will be even more difficult, because it's smaller magnetic particles suspended in a liquid.

 

[Offroader]

When is the FF fluid going to be available for purchase from Justin?

 

[Mammalian04]

When is the FF fluid going to be available for purchase from Justin?

Been selling for a few weeks.

http://www.ebikes.ca/shop/experimental/statorade.html

Someone mentioned in this thread which of the 2 suspension fluids is better but it don't recall which one.

 

[fechter]

Someone mentioned in this thread which of the 2 suspension fluids is better but it don't recall which one.

I don't think we know the long term results yet. I'd go for the ester-based stuff.

 

[Offroader]

Thanks Mammalian04. I didn't think it was for sale because nobody has mentioned yet that they have used it.

 

[Kodin]

I bought a tube of the synthetic, but I'm still in the process of re-engineering my motor before I even mount my motor to a frame. ...which I also have to finish building.

 

[themadhatter106]

I've added ferrous fluid and drilled my motor with only four holes on each side plate. The cooling is a huge improvement. I'd wager a guess that the more air cooling holes you have the faster junk will get in the hub and gum up the ferrofluid. Also depends a lot on where you ride and the season.

Where I bought it it's so cheap I wouldn't mind replacing it periodically: http://www.ebay.com/itm/111723385403

Assuming the ferrofluid does gum up eventually, why couldn't you just add a few ml of some type of light oil? I don't paint my stators but instead spray CorrosionX and I've never had a spec of rust even with all weather winter riding. Maybe spray a little oil in the hub occasionally as a maintenance task to keep the FF working well.


Also, if your running drilled side covers maybe it would be worth it to add more than 5 ml of ferrofluid. Larger amounts of fluid will be able to take more grime before it gums up.

 

[travellin]

Ryan Biffard (Director of Powertrain Engineering at Zero Motorcycles) mentions Justin and Statorade during the Q&A session of this ZeroCast presentation:

http://livestream.com/accounts/14139273/events/4534534

The whole thing is interesting but skip to 34:18 for the comments.

 

[sendler2112]

Ferrofluid is probbably a lot less useful for an inrunner motor where it would be further transfering the heat from the windings which are already on the outside, to the magnets on the inside with nowhere else to go. And flinging off the inrunning magnets at high rpm to fly around in the motor and stick again, creating drag.

 

[spinningmagnets]

Yeah, the RPMs on a geared hubmotor are too high (plus the rotor is isolated from the aluminum sideplates) and the inrunners (like the Zero motor) don't need FF to transfer heat to the outside. FF is perfect for an outrunner under 500 RPMs, like the DD hubmotors.

 

[Kodin]

Madhatter, you lose efficiency with more fluid; The ~5ml amount is to bring the fluid to a light contact. As you add more fluid you add more fluid friction, which lowers your efficiency. The whole point of this is you put "just enough" to make contact, but not so much that you add more drag.

 

[justin_le]

Where would be the best place to drill the side cover for injection of Ferrofluid? Left side close to bearing or closer to the windings?

It really makes no difference since the FF will find its way to the magnet gap pretty effectively. For the most discrete fill location, I think that drilling out one of the screw holes for the disk brake so that it goes all the way through is probably the most ideal. Then the port naturally stays covered when the disk is screwed on.

What kind of flat black paint to get? I see some got some red paint (rust protect??) to shield the internals, then krylon ultra flat black on the side covers. Others has gone for flat black over all of the internals. Krylon ultra flat black was mentioned earlier - but is krylon tested and compared to other flat black paint regarding what drops the temperature the most ?

As I've shown previously, the effect of black paint is measurable but pretty small (much much less than vent holes or FF) in terms of its contribution to motor cooling. So the effect of one brand of black vs another is going to be basically indistinguishable. I would be more attentive about making sure of it's compatibility with oils than worrying about its optical characteristics.