Yes, it can be done and it is quite effective using relatively small amounts of ATF low viscosity, or better yet ultra-low viscosity.Has anyone had any luck, good or otherwise, partly filling your geared hub motors with automatic trani fluid ( ATF)?
Interested to find out what the cooling results were, as well as what type and how much ATF was used, any leaking issues etc?
True, Statorade is useless for geared motors since it sticks to the magnets so pouring it into a geared hub motor and hoping for the best would not be a good idea.Statorade for DD. Neither is appropriate for gear drive hubs.
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.
In regards to geared hub motors, the idea is to close the air gaps with the stator core and the windings with the rotating stator shell and the motor housing. You really can't have the oil, not in contact with the gears.I seriously don't need oil with the gears rotating around in them. If kept below that level, the armature would never touch the oil. In a direct drive the coils that produce the heat are on the outside where rotating oil would not be such a drag.
Thank you for this very clear explanation !Yes, it can be done and it is quite effective using relatively small amounts of ATF low viscosity, or better yet ultra-low viscosity.
The first geared hub motor I tried oil cooling on I used no more than 100ml which kept it below the axle. It is important not to use too much not just for potential leaks but to keep friction drag in the motor low, so the less the better.
Adding small amounts I monitor no-load wattage as long as it does not go too high it is not a problem at all.
The motor which is nominal 500watts I was running at up to 1500watts and naturally it was getting hot quite fast, up to 100c and beyond with full throttle.
With the ATF spinning around and closing the air gap the highest it hit was 65c which is quite impressive.
I can monitor temps with an internal thermistor and cycle analyst so those numbers are a fact.
The trickiest part naturally is sealing the motor. A motor with a high waterproof rating would be ideal but using appropriate silicone o-rings for the axle to bearing and silicone gasket material in the rotor bolt holes (not too much) and some thread sealer, and around the motor housing cover, as well as the cable exit and entrance can work quite well if the surfaces are prepped properly.
Right, I understood long ago that Statorade is for DD motors NOT GH's. Besides sticking to the magnets it also has iron partials ( I think) which would not be good with the gear teeth. Someone dosn't understand that ATF and Statorade are two totally different animals, so naturally they are confused.True, Statorade is useless for geared motors since it sticks to the magnets so pouring it into a geared hub motor and hoping for the best would not be a good idea.
However, both types of motors geared and DD have been successfully cooled using ATF fluid. Mid-drive motors have decent air cooling the way they are built so a bit of oil may or may not be of much significance to cooling, but it certainly could be worth a try as an experiment
For anyone riding off road at relatively slow speeds and needing high torque...my recommendation is to go with a Mid-Drive motor like the Bafang BBSHD because you can utilize the bikes gearing as well as the motors gearing to keep the motor spinning at an efficient rpm and produce less waste heat.
Thank you for this very clear explanation !
I have a couple of questions:
Do you need a breather port for the air in the motor as it expands and contracts with the heat cool cycle?
How did you introduce the ATF into the motor?
Do you have a pic of the o rings for the bearings?
And finally, did you just smear the sealant on the outside of the motor cover or remove the cover?
Thanks
A properly sealed electric motor requires no vent only cooling, in this case, it is probably not a good thing at all, in the long run, to have a vent since it will lead to a bit of fluid leakage which no one wants.
But... If you can afford it you can test it with very good results, which is all you really want who really cares about a tiny amount of seepage.
Open a motor up and seal it as best you can from the inside out and get great results with minimal seepage using a small 1 or 2 mm vent hole near the axle, preferably with some absorbate material covering it.
Just make sure your vent is not on the rotor side, as it suggests a vent is basically a leak don't put it on the rotor side as some unfortunates have done.
I filled the motor I have experimented on with a drilled and tapped hole in the outer shell using a brake bleed kit, putting the hole there also makes it easier to drain, you could use one of the rotor bolt holes you left unplugged as well, not so easy to drain through though.
By the way, your motor probably has grease on the parts it will dissolve with the ATF sloshing around so you will want to change it after a while, that's if you did not bother to clean off with mineral spirits prior.
Instead of putting o-rings which most motor axles don't have channels for... and if you don't have the means to cut your own to put o-rings in, you can put silicon sealant on the axle to seal the air gap between. You don't want excessive material interfering with the bearing locknut fit and be sure not to interfere with its inner and outer bearing race rotation using too much sealant!
As a more advanced option which you probably accomplished with proper sealing anyway if you don't want any leakage whatsoever from an enclosed space like a motor you really need to create a vacuum-sealed environment, it is actually easier to accomplish with the same materials plus a vacuum pump to ensure all is sealed!
Hope that helps a bit I can't write a step by step guide since there are so many motor configurations and it really is a wide-open topic with many unique solutions, only people that have failed at it will disagree
You are using the ATF in place of the motor grease?
Yes ATF is excellent for this purpose and why it is used in Transmissions the low viscosity can travel easily in the many narrow passages while still providing excellent lubrication. Don't use CVT fluid it is thicker and made for continuously variable transmissions.if I understand correctly ;
You are using the ATF in place of the motor grease?
You drilled a drain hole w/ plug on the very bottom of the motor,( between the spoke attach points)?
My only concern is with sealing the bearings, do you know of any pic or link that would clarify just exactly where this sealant should be placed?
Thanks
Very very useful information !Yes ATF is excellent for this purpose and why it is used in Transmissions the low viscosity can travel easily in the many narrow passages while still providing excellent lubrication. Don't use CVT fluid it is thicker and made for continuously variable transmissions.
The initial downside when you add the ATF and it sloshes around for a while it will combine with the grease and raise the viscosity which defeats the purpose of using ATF, it won't hurt anything but it will increase internal resistance which you don't want.
So let it do its thing and then after a bit drain it and refill with fresh ATF, you may have to do that more than once so it is probably better to clean it up, to begin with using an appropriate degreaser.
Don't use that stuff on the windings whatever you use, it is unlikely they are contaminated with grease anyway.
I still recommend a drain and refill regardless of how well it is cleaned up just to get rid of any contaminants or bits of debris.
One thing I have noticed having opened up quite a few motors is they actually use very little grease those gears are very tuff, especially the blue composite ones.
And yes I drilled and tapped an M5 .8 thread common on bikes, right next to the motor housing ring gear, there is a bit more room there and the shell metal is good for a couple of threads which is all you need, again motors vary and you will likely have to grind down a button head screw a bit unless you make a thicker fiber gasket, seal with blue Loctite.
As for the gasket material for the bearings just rub some oil-resistant gasket maker or sealer on the inner bearing surface and a bit on the axle, if the tolerances are tight which they should be you won't need much, remember to let is set for the recommended amount of time before putting the oil in.
And clean any that happens to get on threads.
This is a work in progress for me there is no manual and so just remember there is a certain amount of trial and error to all this you will have to keep an eye on things and make adjustments to how you go about it.
And as I said previously you will more than likely get a bit of seepage from any vent hole you drill, I have never had oil dripping or shooting out though.
As others have done though I just used some gasket material over the hole just to be on the safe side.
I mentioned creating a vacuum, handheld ones with gauges are common, if your motor can hold one it probably will not need a vent at all (hint). And it means you did an excellent job of sealing the motor.
To wrap it up (and probably where I should have started) unless you are like me, an enthusiast with no problem experimenting and have temp sensors installed and programmable controllers with detailed displays, etc. just to push your motor to the limits it may very well not even be necassary for you or anyone to even bother with this since many bikes and kits are most likely designed to work within a specific range and for specific weights and uses.
Electric motors can take a lot of heat we are talking over 100c to 120c and even more depending on the quality and build of the motor where your windings will likely start to burn and If you get to the 130c range you will start to have real problems with the gears, and the magnets can lose their magnetism.
When you are hitting or getting close to those numbers yeah you need cooling if you want the motor to last.
If you go for it let us know how it goes!
I will update things down the road maybe with pics and possible video, again though there are many different motors and configurations, there is no manual no kit just ingenuity and skill.Very very useful information !
I will save this link for future use. I had modded my controller for more amp and was concerned about overheating the motor, but all is well.
Love to learn how to oil cool these motors though.
Thanks
Updates will be great.I will update things down the road maybe with pics and possible video, again though there are many different motors and configurations, there is no manual no kit just ingenuity and skill.
You never mentioned the motor you had a concern with.
Anyway, I did my first motor complete including drying time in less than 3 hours, If I can do it successfully with a halfass job anyone can
Please....you make some very incorrect statements.Statorade for DD. Neither is appropriate for gear drive hubs.
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 actually looked at that kit last year.Updates will be great.
I actually don't know what brand of GH I have, as the seller will not say. I got it from Calibike, the 52v 1500w kit.