How Teslas and most EVs keep your car cool probably won’t slow you down
If you drive an underpowered car with an automatic slush box, you know how much more pep your beater has with your A/C off. Even if we don’t fully understand the magic of air conditioning, we know there’s an accessory belt running the A/C compressor powered by the engine.
Turning on the A/C produces a parasitic draw robbing your 75 wheel horsepower Honda Civic of precious off-the-line speed. In an automatic, your shifts become even slushier.
This mechanical phenomenon inspired one of my favorite memes.
Using AC in your Tesla will not make you slower since Tesla’s AC system and AC compressor is powered by its own integrated 400-volt electric motor. Since the AC compressor’s motor is independent of the main drive motors, the AC system does not cause a parasitic draw to the drive wheels.
Below is a diagram provided by Munro and Associates. Illustrated are two main cooling (and heating) functions of the cooling system, providing chilled coolant to keep batteries cool if called upon and to condition cabin air.
Actively cooling air is an AC compressor combined with a 400 volt electric motor into one compact unit.
Here’s what a used one looks like.
Air is cooled just like a traditional car. An AC compressor compresses refrigerant in a cooling system into a higher temperature gas before its routed to a condenser.
A pair of condensers, each equipped with its own fan, turns hot gaseous refrigerant into a cooler liquid state. That refrigerant is pumped through the in-cabin evaporator coil where heat is drawn out, cooling the in-cabin air. That warmer liquid refrigerant is then routed into the compressor where the entire cycle begins again.
The AC compressor is also responsible for cooling a glycol loop to keep the electric motors running the drive wheels and larger main traction high-voltage battery cool (or warm depending on outside conditions.)
As mentioned, since the AC compressor’s integrated electric motor draws power from the main tractive battery, only overall range takes a hit.
The main driver motors can still draw as much power it needs from the battery during a hard acceleration launch despite the AC running.
So, when Jay Leno quipped he broke the production 1/4 mile record in a Tesla Model S Plaid with the AC running, knowing how the AC system works, it’s not that surprising.