Electric car summer idling: Better or worse than winter?

Research

May 26, 2023

Last year our team responded to an unfortunate opinion article about electric cars getting trapped in blizzards. In the testing and analysis, Andrew Leonard found that his Tesla could easily idle with cabin heat as well as its combustion engine counterparts.

Andrew found that he could blast the heat in his car on High for 12 hours or keep room-temperature conditions for up to 50 hours. We can likely close the book on winter idling concerns.

What about EV idling in summer heat?

It’s important to start with a quick physics lesson before explaining the answer to that question. Electric car efficiency decreases in cold conditions because of two reasons:

Chemical and physical reactions in the battery occur slower in cold temperatures so the car’s battery management system (BMS) uses some power to keep itself warm.
Electric cars also have to make their own heat because they don’t produce “waste heat” like gasoline engines.

Both of those reasons cause range to decrease in (very) cold conditions. Side note: If you want to see more about EVs during the winter, we did a cold weather study that compared more than a dozen popular models.

In warmer conditions, batteries are more in their happy place, at least to a certain point – nothing likes baking in extreme heat. Since warm weather does not create the same friction in batteries as cold weather and your electric car’s A/C is generally more efficient than its heater, that means an EV can idle even longer in the warmer months.

Idling test in summer conditions

Our team put this to the test with 4 electric cars in different warm-weather conditions. Each vehicle set its interior (cabin) temperature to 70F to 72F, parked the vehicle outside in the sun, and let it idle for one hour.

Vehicle

2018 Tesla Model 3 LR (75kWh)
2019 Tesla Model 3 SR (50kWh)
2020 Tesla Model 3 (50kWh)
2022 Rivian R1T (135kWh)

Interior Temp.

Weather

80F Sunny
80F Sunny
68F Sunny
77F Sunny

% Battery Used

Several interesting things jump out from this test.

All of these electric vehicles could idle for more than a day in warm conditions with their cabin at a crisp 72F.
The Tesla Model 3 Standard Range uses a larger percent of its energy each hour because of the smaller pack, which falls on the lower end of ranges for EVs sold in 2023.
A longer range EV could potentially idle with A/C for 4 days.

Obviously, this is a small sample size, but the early results are promising. We are planning additional analysis here with hundreds of vehicles so we will update this post when we have more data.