Testing by AAA has found that how far an electric vehicle can travel on one charge varies widely depending on the weather. Frigid temperatures can reduce that distance by 57%.
The research is important to the Automobile Club of Southern California because it maintains mobile recharging trucks for people who misjudge how far they can go in their electric car.
"EV drivers need to carefully monitor range in hot and cold weather," said Steve Mazor, the engineer who manages the Southern California club's Automotive Research Center.
The center conducted tests on a 2013 Nissan Leaf, a 2012 Mitsubishi iMiEV and the electric version of a 2014 Ford Focus.
The cars were tested for city driving to mimic stop-and-go traffic and to better compare with Environmental Protection Agency ratings listed on the window sticker, AAA said.
The average EV battery range in AAA's test was 105 miles at 75 degrees but dropped 57% to just 43 miles at 20 degrees. Heat also sliced the cars' ranges but by not as much: The cars averaged 69 miles per full charge at 95 degrees, 33% less than in 75-degree weather.
The research center tested the cars following the same EPA drive cycles that provide the data for the mileage window stickers on new cars. The vehicles were charged up and then driven on a machine with rollers called a dynamometer in a climate-controlled room until the battery was exhausted.