[cyberax]

Cooling systems for regular ICE cars need to dissipate around 1/3 of the nominal engine power. So if you have a modest 150hp car (112kW), the cooling system needs to be able to dissipate around 40kW of power. In reality it's even more, because you need to have some safety margin.

The cooling system in an EV are much, much smaller. You're looking at maybe about 20kW for a Tesla Model 3 with 450hp motors, and this includes heat rejection from the air conditioner.

(on the other hand, the air conditioner on EVs is a _critical_ component, because the main battery can't tolerate being heated to more than +90C like regular ICE engines)

[nradov]

Most of the waste heat created by an ICE is dumped out the exhaust, not the radiator.

[cyberax]

Yup. The "1/3-rd of mechanical power" is an empirical rule.

However, it seems reasonable once you think about it.

The mechanical power of a car is about 25-30% of the total heat generated. So a 150hp car actually generates about 450hp of heat energy. Most of that power is indeed lost in exhaust. The 1/3 of 150hp is 50hp, around 10% of the total.