Good! Someone finally oil cooled a hubbie!! HS3540

[John in CR]

On my other motor I run regen braking so I don't use a back brake caliper so no worries about clearance there.

Hmm. I use regen AND a disc brake. I find that my regen braking just does not cut it in case of an emergency brake. In such a case, I want both my front and rear hydraulic calipers to be fully engaged in providing the maximum braking without blocking.

kids this is good advice, :wink:

It depends on the rig. I run regen as the only rear brake on my SuperV, and at 5.5kw peak braking it test the limits of traction. The only time I miss a rear mechanical brake on that bike is at very low speeds where there is no regen braking. On my cargo bike I run throttle activated regen with a very gentle stopping force, so yes that bike requires a rear brake.

John

 

[Andje]

I feel like skidding my rear tire in an emergency does not compare to instant full regen of about 5000w. I doubt my calipers can absorb 5000w as efficiently as my motor.

 

[hjns]

I feel like skidding my rear tire in an emergency does not compare to instant full regen of about 5000w. I doubt my calipers can absorb 5000w as efficiently as my motor.

Agreed. However, in an emergency stop, I use both regen AND calipers. The regen will bring me back to 20kmh only. Also, adding the brake force of my hydraulics to the regen allows for an even better controlled stop. And yes, of the 6kW power, 5kW may be produced by the regen, and another 1kW by my calipers, which is very nice.

 

[The Stig]

Well it sounds like the NZ geeks are having some luck with this oil cooling thing
http://www.ev.geek.nz/viewtopic.php?f=32&t=162&sid=7c6fe6e8b7a1a2f8e8879728ce4247fd&start=150

Anyone tried this with a 9C or MAC?

 

[bmrcfreak]

BUMP!

Can you guys who have oil cooled your motors report back your long term results? Have any issues come up since you oil cooled your motors? I have a MAC motor I'm thinking about oil cooling, but I'm concerned about long term oil leaks or other issues developing...

 

[The Stig]

Nice Thread Dig,

This one has been getting more action: http://endless-sphere.com/forums/viewtopic.php?f=2&t=37972&start=550

 

[Bullfrog]

Hi parabellum, any updates on how this is working out with use ?


This oil cooling sounds like a good idea to me, so I had a crack at it too.
I also modified an MXUS DD hub as follows:

1) Added a temperature sensor in the windings near the top of the motor ( away from the oil pool )

2) used silicone gasket sealent to fix the covers and seal the axle slot.

3) Added a threaded filler hole in the side cover for the oil.

4) Filled the hub to various levels with mineral ATF (Dexron II) and measured the no-load current @ 36v

View attachment 74269

View attachment 74270




At 400ml fill, the oil level is just below the axle, where the filler hole is in the above photo, (you can just see the red coloured oil inside the hub).
With this much oil, the motor makes a satifying, just audible ,sort of sloshing noise when it is spun up.


No oil, no load current = 1.05 A
150 ml oil @ 18 degrees C = 2.0A
200 ml oil = 2.0A
250 ml oil = 2.1A
300 ml oil = 2.15A
400 ml oil = 2.15A

I will leave the oil level @ 400ml and install it on my bike to test the thermal effects.
The bike currently has an identical motor fitted, including a temp sensor (just no oil), so the comparison will be interesting.

Burtie
edit: corrected reference to Dexron II

FWIW, you don't need nearly that much oil in a Direct Drive motor. All you need to do is bridge the gap between the stator and the outer shell so heat can transfer across the gap more readily than with just air in the gap. I would run your no load experiments again and try starting with 50 ml, then 100 ml, then 150 ml...my guess is 100 ml would be plenty but I'd rather have a little more than needed than fall short and still have an air gap between the stator and the outer shell.

Statorade is the best cooling fluid (ask Grin Tech how much to use) but a low viscosity, synthetic, ATF like "

Super Tech DEXRON VI/MERCON LV Full Synthetic Automatic Transmission Fluid" ​

from Walmart would be a good choice. Synthetic will hold up to higher temps better and "Dexron VI/Mercon" requirements are fairly low viscosity.
BUT make sure you seal your motor because any leakage on your brake pads/rotor will immediately make your brake useless.