Hi,
very long time lurker(since the beginning on endless), new member here.
I will post some photos here of how I am modifying my APS 6374 motors for a mountainboard.
The first problem is, that the ntc sensor is too far away from the windings, so it may be too late when temperature on the sensor reaches the set limit.
The second problem is, that windings get loose with time and this increases noise, but when you use normal epoxide, you are worsening cooling capabilities. So when we use thermally conductive silicone or epoxide, it should help with that.
Silicone I used is too thick to flow everywhere, so the results are not exactly as I imagined. I will try to mix epoxide with some powdered aluminium oxide to make it thermally conductive and use it on the rest.
Open the motors…
Add new NTC sensor near the winding.
And pour the silicone.
Remove mold.
Clean up with scalpel.
To be continued…
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but aluminum oxide is not electrically conductive? I don’t really know anything about it.
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Adding this to my watch list, thanks for sharing 
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It’s not when it is dispensed as powder in electrically non-conductive solution, because circuit is not closed.
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Oh gaaaawd.
Silicone should definitely keep the windings from loosening. I wouldn’t think for a moment it would help the magnets from being cracked like epoxy does tho. (though in stators this is rare, at least in my experience)
Also, unless you’re ~250lb on 2WD trying to push ~40mph+ up a hill, fully encased in tradition epoxies isn’t the slightest issue with regards to heat. May not even be at that point, but I won’t attempt to say what I don’t have proven raw data for.
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While that may be true, keeping electronics as cool as possible is not a bad idea. Something that seems to often be forgotten on this forum.
Just because your ESC/motor can take 80C doesn’t mean that it likes it.
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What specific material did u use to pot the windings? In my experience it was detrimental to getting heat out and I’d used some expensive stycast stuff. Vacuuming it is important and with think stuff was told u can slam it in by repeatedly releasing the vacuum. Or else u get hot air pockets.
They make aluminum filled stuff.
The one motor I know of that had an internal short was in a potted motor. I don’t know exactly what happened but the expansion rates of the material vs the wire could’ve been the problem.
The best stuff ive been wanting to try potting with, but enough for a motor cost like 100$ is indium metal. Got some n then changed my mind: too expensive experiment.
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Calling them electronics is a stretch tho. A bit more true if using sensors… but it’s literally laminated magnet, metal, and copper, that is coated in an enamel that can take such heat boiling lye is needed to strip it.
Does heat make more Ed n Eddie’s come out @hummieee?
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Silicone rubber with thermal conductivity 2W/m-k.
There was some research with similar stuff.
Conclusion
The results of testing both at KTH and at LORD Corporation clearly show the benefits of potting with thermally conductive materials. Motors potted with CoolTherm SC-320 encapsulant offer more horsepower and torque at a given temperature and should provide lower copper losses and higher reliability at the same torque (Figure 3). The tests demonstrated an improvement in copper losses of about 10% and a 30 °C difference at the highest applied load and torque. Alternatively, at the same highest temperature, there was a 16% improvement in torque with the potted motor.
source: Improving Automotive Motor Power Density with Thermally Conductive Materials
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All heat increases resistance and loss of efficiency and snowballing of heat.
Wire is rated to 20,000hours at some temp. What temp wire they use is likely unknown and if u go beyond the rated temp can be much less time. Time till shorting. Which can be dangerous
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O. How much was it? And then it’s flexible n safer
Depending on the magnets type, for some 80°C may be too much
Either way - in esk8 - you’re balancing a trade off of “how long until my motors break from esk8 shit” - something we know happens, a lot - vs “how much reduction of life is brought from excess heat/other unknown causes by complete battle hardening” - I think we know which of those is the better choice…
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I’m a fan but I think it can still be detrimental if not vacuumed in and if it’s not transfer I g the heat and instead acting as another layer. Transferring to the motor case or something
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My method uses a pretty decent amount of pressure that has it seep pretty deep into the windings. Definitely not like a vacuum process, but still some.
Wonder how it will go. Hope u post temp results. I believe it will still got hotter. But at least more secure.
The wires on top look hella fragile.
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Did u get the lord stuff or what? I think they have the most conducive resin
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Tranferring to motor case was the plan, but silicone was too thick to flow down here.
I will test it, but first have to finish my new build
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Just some polish basic stuff, cost like 10 usd for 100ml
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