Ferrofluid, motor coolant? or another snake oil?

I found article https://www.google.ca/amp/s/electricbike-blog.com/2015/12/18/ferrofluids-join-the-ebike-motor-cooling-revolution/amp/

here says, ferrofluid (magnetic fluid) can use on hub motors for better cooling performance. Have anyone used it before?

why can’t we just use mineral spirit instead?

There’s a limitation to how much ferrofluid you can use. Do not even try using mineral spirit. You probably dissolve the glue holding the magnets to the rotor plus it’s a volatile solvent. You need to use nonconductive. noncombustible, inert substances such as mineral oil.

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Thanks I forgot the mineral spirit dessolve manythings.

Ferrofluid effectively works as a thermal wiper cause it stores itself between magnets space upon rotation. It adds a tiny bit of drag (non-noticeable on e-bike type hubs) but also raises the thermal “patch” between stator and rotor.

If you have waterproof hubs for your skateboard, you can try and use it (maybe 1ml, 1,5ml would be more than enough for a tiny can). Note also that on e-bike style hubs, heat is radiated toward the outside can of the motor. There’s also this mighty mod they do where they add alu fans around the can, so the can itself becomes active cooling while rotating.

On a skateboard your hub motor is stuck inside the PU wheel, the heat would go straight to it… either not being dissipated in the end or causing the PU to melt. See what I mean ?

Now maybe it can do wonders on Carvon-type direct drives, since the cans of Direct drive are exposed outside of the PU (and the wheel remains intact).


I don’t think pu melt that easy, if it works it will be great way to reduce thermal cut out on hub motor.

Motor needs to be sealed to use this.

Pu generally deteriorates at 170f

If your hub motor got to 170f wouldn’t you have bigger problems than your PU melting?

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no way, thats lower than boiling water

Yea. Not melting temp but deterioration. Often turns to white powder under stress or stretches If ur winding insulation, and magnet currie number, and bearing grease can go higher u can, but the copper wire resistance goes up w heat too so have less eff

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oh that makes sense.

Justin Lee from ebikes.ca made lots of tests using it with ebikes hub motors and also with some eskate hub motors





Thanks, it seems to improve 20~50% heat dissipation over “sealed”. FF seems to evaporate as the motor heats up tho

as alternative, also found sythetic engine oil along with ATF, does the same tric tho, it could be messy and needs about 50ml based ond 250w sized hub.

not so sure why one would use ATF over engine oil as it cools and rubricate better and does not burn well.

Is it because ATF is less viscos and have less drag? I’m not so good with cars😝

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