AAA shows consumers how temperature extremes hurt EV performance

It is well known in scientific and automotive circles that extreme temperatures combined with the use of heating and air conditioning systems can cause lithium ion batteries used in electric vehicles to discharge faster. On Thursday, the AAA issued a report quantifying that degradation to help average consumers better understand the attributes of electric vehicles.

Electric vehicle driving range decreased by 41 percent when the mercury dips to 20°F and the heating system inside is on, according to new AAA research. That means for a 100-mile route, an electric-powered vehicle could go only 59 miles. Lower range translates into more frequent charging and higher operating cost for users.

The findings raise questions about whether automakers can make EVs appealing to consumers in cold-weather states. More than 1 million plug-in electric vehicles have been sold in the United States, but they still only represent fewer than 1 percent of total sales.

"As long as drivers understand that there are limitations when operating electric vehicles in more extreme climates, they are less likely to be caught off guard by an unexpected drop in driving range," said Greg Brannon, AAA's director of automotive engineering and industry relations, in a statement.

AAA's research also found that when outside temperatures heat up to 95°F and air-conditioning is used inside the vehicle, driving range decreases by 17 percent.

The use of heat when it's 20°F outside adds almost $25 more for every 1,000 miles when compared to the cost of combined urban and highway driving at 75°F, according to the study of five EVs on a dynamometer.

Loss of range at low temperatures is due to the reduced mobility of electrons in the battery, the use of thermal management systems in many cars to keep the battery warmed and the fact that an EV has to generate electricity for heating rather than relying on waste heat from an internal combustion engine.

Experts recommend owners "pre-heat" or cool down the inside of the vehicle while still connected to the charger and park in a garage when possible to reduce demand on the vehicle's battery.

"The research clearly shows that electric vehicles thrive in more moderate climates, except the reality is most Americans live in an area where temperature fluctuates," said Megan McKernan, manager of the Automotive Club of Southern California's Automotive Research Center. "Automakers are continually making advances to improve range, but with this information, drivers will be more aware of the impacts varying weather conditions can have on their electric vehicles."