[FabHK]

Electric engines are already very efficient (particularly compared to internal combustion). If you go from 90% to 95% efficiency, you don't save much in terms of battery.

ETA: Internal combustion engines half a century ago had an efficiency of 20%, now they're at 40%. That cuts the fuel you need to carry in half. Electric engines are near 100%, and as I said, going from 90% to 95% efficiency cuts required battery by a bit more than 5%, so peanuts.

[ajuc]

Going from 90% to 95% efficiency you're halving the thermal loses, thus reducing the need for cooling by half. It's a big deal.

Same with going from 99% to 99.5% efficiency. It still reduces the cooling needed by half.

[FabHK]

I was responding to

> I think the cited weight loss comes from energy efficiency gains leading to less battery capacity needed.

So, no, the efficiency gains of electrical engines do not lead to significantly less battery capacity needed.

[testdelacc1]

> reducing the need for cooling by half

But the motor is not the only thing that needs to be cooled. It’s mainly the battery, which has a narrow operating range. The power electronics that convert AC to DC also need to be cooled.

So you’re halving the cooling needs of the motor, which is nice but small compared to the other two. And even then, total cooling doesn’t impact range that much compared to warming the battery in cold climates.

I think you’ve overstated your case.

[ssl-3]

Half is half.

If we halve waste-heat generation for a practical widget enough times, then we won't need liquid cooling for that widget at all. If the trend continues and gets good enough, then maybe we can get all the way to a complete passive-cooling snoozefest.

That's pretty boring, but boring is good. The systems we use every day without a thought because they boringly Just Work are, perhaps, our greatest successes.