Energy usage of the AC in very hot cliemate

[David99]

I did some tests today measuring the power & energy of the AC in very high temperatures. It was 106 / 41 today in Northridge, CA. It used a little over 1 kW to keep the car cool. Here is a short video about it. I also did some testing driving. While I didn't include that in the video, the energy usage of the AC is the same driving compared to being parked.

For 2 hours of driving, you would lose aprox 8-10 miles of range. Let's say you drive 70 mph average, that's 140 miles total. 10 miles is aprox 7%. That is pretty efficient IMHO. What matters is the temperature split (outside vs inside). If you adjust you inside temperature down, you are going to use more. Another thing to consider is when you park the car and then get in, the AC uses a lot more initially to cool the cabin down. Sure you can start the AC from the app before you get in, but it still needs the same amount of extra energy. Anyways, just thought it might be interesting to some.

Edit: Mod, can you please correct the typo in the subject!

 

[Snowstorm]

I believe the AC can use a max of 3kw, but that is on full tilt. During stead state, 1kw sounds about right. The temp delta in summer even in a hot place is less than winter in a cold place. 40C to 25C is a diff of 15C, in winter it can be -15C to plus 18C, a difference of over 30C. There is solar heat gain so it isn’t quite that extreme.

Plus, resistive heater is only 100% at best. AC is heat pump so it can be 2-300% efficient.

 

[David99]

I believe the AC can use a max of 3kw, but that is on full tilt. During stead state, 1kw sounds about right. The temp delta in summer even in a hot place is less than winter in a cold place. 40C to 25C is a diff of 15C, in winter it can be -15C to plus 18C, a difference of over 30C. There is solar heat gain so it isn’t quite that extreme.

Plus, resistive heater is only 100% at best. AC is heat pump so it can be 2-300% efficient.

I have to check it again, but I think I have seen the AC at close to 5 kW. It was in 113 F desert driving and the car told me it needs to use part of the AC to cool systems down.

But you are absolutely right about the larger temperature difference in winter cause a higher energy consumption. If you compare efficiency based on ambient temperature it is almost the same in hot or cold.

 

[BigNick]

Pretty sure part of those kW for AC is being used for battery cooling also, if you feel warm enough to run the AC your battery probably wants some cooling also.

 

[David99]

Pretty sure part of those kW for AC is being used for battery cooling also, if you feel warm enough to run the AC your battery probably wants some cooling also.

The battery likes it toasty. The car won't start using the AC to cool the battery unless the battery temperature is well above 50 C / 122 F. At the time I did the test the car was not actively cooling the battery.
The only exception is when charging at a Supercharger. Then the car will start using the AC at a lower temperature to compensate for the massive heat buildup inside the battery.

 

[Lasttoy]

I called Tesla about my battery cooling. He said, "battery temp is near 70f" the fans are cooling at the super charger because of the high voltage heat. He said temp should be between 65 to 75 all year .