OTish: Electric car motor cooling

Stihl290 · Feb 10, 2017

So there is this video on the BMW i3 motor. I was kinda surprise there wasn't some type of active internal cooling system. It appears to be fully enclosed with no cooling fan or some type of heat exchanger system. I'm not sure if or how warm the motor would get but ideally wouldn't it be better to keep it cool for longevity of the motor? It has a claimed range of 80-114 miles, per charge I assume. So if you were driving on a highway in a hot climate going 60 miles non-stop to where ever at 60 mph, that's 1 hour of continuous use. I would assume the motor would get warm at the least.

BMW i3 Electric Motor Production - YouTube

Ziggy2 · Feb 10, 2017

The case is water cooled. The energy density is high enough on all of the BEV motors that they would shortly self destruct from over temp if they did not have a water cooled heat sink of some sort.

Usually the manufacturers cool the outer motor case.

GregSY · Feb 10, 2017

Other than the use of a lot of fancy robots (probably to satisfy the German need to be...German) I don't see a lot of special techniques in that 'motor build'. There's not much that separates that motor from a billion other low voltage electric motors.

adama · Feb 11, 2017

You need to remember too that compared to a IC engine a electric motor dissipates but a fraction of the heat, most are in the 80-90% efficency range (unlike a IC 25-35% range), add there overall size, connections to other parts and they need some but surprisingly little additional cooling.

Most of the heat build up in most common motors will be during acceleration, there really not working that hard at cruise.

JST · Feb 11, 2017

Rather disappointing video, 90% of the interesting stuff left out. Not even "secrets", just stuff like whatever they did with the messy coils that were wound and then more-or-less dropped in a pile at the beginning. Obviously they were stuck into the stators, but......

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OTish: Electric car motor cooling

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