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Comment by Tostino | Hacker News Reader

The first step to dealing with heat at high kw, is to not generate the heat you have to dissipate in the first place. Which means chasing smaller and smaller efficiency gains, because that reduces heat generated.

The more of the energy going into moving the vehicle, the less heat the motor has to handle.

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Sure, but at 50kw/kg at 99% efficiency is still 500w/kg, which is cray cray. Like ‘glowing red hot shortly’ type of crazy with just passive cooling.

And there is no way this is 99% efficient.

So my question still applies. Even 98% is 1kw/kg, or 1kj/sec. or around 3C rise per second assuming the mass is 100% nice clean copper (it isn’t). Everything else will be worse.

Not even counting increasing losses with temperature, it will be a molten puddle pretty quick at that rate without some major active cooling.

I was waiting to see in the comments EXACTLY this question: There is no way to dump this heat. 1000hp? Yeah, maybe for a few seconds, even with oil coolant pumping through there. Then how to dump the heat from the oil. And further thinking, if they ever get this to be a hub motor, how in the world are they going to pump coolant through 2-4 hub motors and then to a radiator that can dump that rate of heat rise, especially since oil is a lousy coolant (relatively speaking).

Those could be answered by large radiators or the like - when outside the ‘has to be dense’ path. The issue the motor has is exactly that it needs to be dense - and has a lot of power going through it.

Liquid cooling at least for now should work - as long as it stays below the flash point of the liquid I guess.

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