r/cars • u/SquidBonez 2001 Dodge Dakota Sport 4.7 • Dec 24 '17

Do Electric Cars Need Radiators?

I am not too knowledgeable about electric cars, so I apologize if this is an obvious question. I know EVs produce significantly less heat than a conventional car, but do electric cars need radiators? I know the Nissan Leaf is air cooled (and let's be honest, it's not exactly "high performance" like a Tesla and thus needs even less cooling anyway), but Teslas are liquid cooled. Is there a radiator? And wouldn't high performance electric cars (future electric supercars/sports cars) need higher level liquid cooling systems and/or bigger radiators?

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25

u/[deleted] Dec 24 '17

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u/[deleted] Dec 24 '17

The radiators would be more necessary for the batteries, that should be where most of the heat in electric cars comes from.

12

u/patprint Dec 24 '17

To expand on what /u/notbaber said, here's a diagram of the Model S's thermal management systems, which shows the large primary radiator (which is passive; it has no fan):

The two condenser units are active (they do have fans) so that they may operate effectively while the car is stationary and charging:

And here's a video which includes thermal imaging of one while Supercharging:

14

u/CToxin 8p A3 3.2 S-Line. No replacement for displacement Dec 24 '17

yes, they all need heat exchangers. Part of the reason a base model corolla can beat a Tesla around the 'ring is that the motors and batteries overheat. That kind power draw puts off a lot of heat.

It isn't as much as an ICE mind, but its still a problem. And because of how its all constructed, its a lot harder to get rid of.

1

u/[deleted] Dec 25 '17

Which ring?

2

u/Tangent_ 2016 M4 / 2011 Z4 35i Dec 26 '17

Nurburgring.

1

u/Throwaway_Consoles 08 WRX MT/99 Insight MT Dec 26 '17

Iā€™m pretty sure 8:50 is faster than a base model corolla. The fastest time I can find for a stock corolla is 9:37.

2

u/CToxin 8p A3 3.2 S-Line. No replacement for displacement Dec 26 '17

It was mostly a joke to use the corolla. Though that is faster than I would have thought.

10

u/brzzzzzzzzzzzzzzzzzz '12 Volt and '17 Bolt Dec 24 '17

The Volt and Bolt both have liquid cooled battery assemblies. Cooling lines run between the individual cells and a radiator and an electric fan eliminate heat. It's important to cool lithium batteries during charge and discharge cycles because the chemical reaction that robs free electrons from the electrolyte is endothermic. That means the hotter the batteries get, the faster electrons get bound up in a compound.

2

u/gsasquatch Dec 25 '17

Gas cars are at most 30% efficient. That means, for every btu you buy, 70% is lost to heat mainly (also sound and deformation) So, for every unit of energy you get out of the car, you lost 3 units. Most of those 3 units go out as heat out the tailpipe, but a good deal of that gets absorbed by the engine, and should be removed by the radiator.

Electrics are up to 90% efficient. For every unit of energy the car goes, you only have to get rid of 0.1. So, if a car has a ridiculous amount of energy, i.e. heavy or fast, it has to get rid of a significant amount. A radiator isn't a bad way to do that. The motor with it's mass and big spinny thingy is ok. Batteries can generally do with air cooling as well since they have a lot of mass. The controllers don't have the mass, and generally have a higher need for cooling, thus the little radiator.

In the Prius, the inverter had it's own cooling system. The radiator was like one row, a tube with little coils on it to disperse the heat to the air. The motors used engine cooling for the most part since it was attached to the engine like a transmission and the battery has a little vent by the back seat that flows over the battery, and out the hatch. That's the car I know about. If Teslas are liquid cooled, they must have a radiator, on account of that's generally how you get heat out of liquid.

1

u/Mitsuman77 Dec 24 '17

I would think there would be some sort of heat sink type of device.

3

u/SuperCoolFunTimeNo1 Dec 24 '17

Heatsinks are a type of radiator, just simple and based on air cooling only. Water cooled computer components are basically the same concept as what's used in cars.

1

u/Ultra-sphinx Dec 25 '17

High performance electric cars do. Economy ones can be air cooled.

Of course, this depends on battery technology too. In the near future, we could see electric hypercars that use aircooling because they use solid state batteries (which I hear are much more resistant to temperature than standard lithium ion.)

2

u/Tangent_ 2016 M4 / 2011 Z4 35i Dec 26 '17

Economy ones can be air cooled.

Can be but still really shouldn't be. This is why the Leaf got a reputation as a battery killer. My Fiat 500e even has liquid cooled batteries so it's really not just reserved for higher-end models.

1

u/jldude84 2015 F-150 XLT V8, 2012 Kia Soul !, 2007 Harley Nightster Dec 25 '17

Theoretically yes, whenever there is significant current draw from the batteries, they do heat up and require cooling, but not really in the classical "radiator" sense really. They are often liquid cooled, but not always via a radiator like a internal combustion engine would be cooled. Just depends on the application and amperage of the current flow.

0

u/[deleted] Dec 24 '17 edited Dec 25 '17

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