LOS ANGELES — AAA found that hot temperatures reduced electric vehicle driving range by an average of 8.5% and cold temperatures cut range by 39%, according to new tests conducted at its Automotive Research Center in Los Angeles. The organization previously ran a similar series of temperature tests in 2019 using a different lineup of vehicles.

In the 2019 tests, high-temperature conditions reduced electric vehicle range by 17%, while cold temperatures reduced range by a percentage similar to the latest results. AAA cautioned that differences in vehicle lineups complicate direct comparisons between the two rounds of testing.

"The electric vehicles actually didn't change all that much from back in 2019," said Greg Brannon, director of automotive engineering at AAA. He said range loss in extreme temperatures can be managed by drivers. "It can be overcome. But you have to plan for it." Brannon said.

Electric vehicle batteries are most efficient when ambient temperatures are around 65 to 75 degrees Fahrenheit, and a battery's efficiency decreases when temperatures are much colder or hotter than that range. AAA conducts the temperature tests at its own expense as part of research for auto club members.

The Automotive Research Center is located inside the historic headquarters of the Automobile Club of Southern California. Its test chamber can be set to temperatures as low as 20 degrees Fahrenheit or as high as 95 degrees Fahrenheit. Inside the chamber, a chassis dynamometer with two 4-foot-diameter steel rollers simulates driving conditions for a single vehicle, and vehicles are tied down with heavy, bright-pink chains to prevent them from moving off the rollers. A test ends when a vehicle's battery is drained to the point that it can no longer maintain highway speeds on the dynamometer.

The Environmental Protection Agency estimates that gasoline-powered vehicle fuel economy drops by 10% to 30% in cold weather. Ed Kim, chief analyst with the research group AutoPacific, was not involved in AAA's research. "Internal combustion engine vehicles also lose range in extreme cold weather. This isn't a problem that's exclusive to EVs. This happens to basically any kind of vehicle when it gets really cold." Kim said.

Electric vehicle adoption rates in the United States are higher in warm or mild states than in the chilly Midwest, and state policies and charger availability influence adoption rates. Drivers can mitigate predictable range loss by selecting a vehicle suited to their climate and through forward planning.