AAA Study: Extreme Heat And Extreme Cold Reduces Driving Range Of Electric Cars

According to a recent study from AAA, freezing temperatures can take the charge out of electric vehicles. Electric vehicle owners may experience a decrease in driving range, compounded by the use of the vehicle’s interior climate control. 

New research from AAA reveals that when the mercury dips to 20°F and the HVAC (Heat Ventilation Air conditon) system is used to heat the inside of the vehicle, the average driving range is decreased by 41 percent. This means for every 100 miles of combined urban/highway driving, the range at 20°F would be reduced to 59 miles. When colder temperatures hit, AAA urges electric vehicle owners to be aware of a reduction in range and the need to charge more often to minimize the chance of being stranded by a dead battery.

Cold weather, however, is not the only factor that can influence driving range. 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. Extreme temperatures certainly play a role in diminishing driving range, but the use of HVAC in these conditions – particularly the heat – has by far the greatest effect. 

Additionally, an electric vehicle with a compromised driving range will require charging more often, which increases the cost to operate the vehicle. For instance, AAA’s study found that 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. 

“The appeal of electric vehicles continues to grow since a greater variety of designs and options with increased range have come onto the market,” said Greg Brannon, AAA’s director of Automotive Engineering and Industry Relations. “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.”

AAA tested five electric vehicles, all with a minimum EPA estimated driving range of 100 miles, in partnership with the Automotive Club of Southern California’s Automotive Research Center. Real-world driving conditions were simulated using a dynamometer, essentially a treadmill for cars, in a closed testing cell where ambient temperature could be closely controlled. To determine the effects on driving range, scenarios for cold and hot weather conditions – both when using HVAC and not – were compared to those of driving with an outside temperature of 75°F.

“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 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.”

There are some precautions electric vehicle owners can take during colder and hotter times of year to help offset potential reductions in driving range. AAA recommends drivers:

• Plan ahead. When drivers are aware of the weather conditions before heading out, they can plan for more frequent stops for charging as well as identify the location of charging stations. Drivers can access these locations through AAA’s Mobile app or TripTik Planner.
• Make time to “pre-heat” or cool down the inside of the vehicle while still connected to the charger. This will reduce the demand on the vehicle’s battery to regulate cabin temperature at the onset of driving.
• If possible, park the vehicle in a garage to help stabilize cabin temperature.

While electric vehicle range performs best in areas with warm weather year-round such as Florida, Hawaii and California, drivers in other parts of the country shouldn’t be discouraged. Owning an electric vehicle in these regions just requires some additional planning.

Additional information on methodology can be found in the full report here.