“Batteries are like humans,” says Anna Stefanopoulou, director of the University of Michigan’s Energy Institute. They prefer the same sort of temperature range that people do. Anything below 40 or above 115 degrees Fahrenheit and they’re not going to deliver their peak performance. They like to be around 60 to 80 degrees. As the temperature drops, the electrolyte fluid inside the battery cells becomes more sluggish. “You don’t have as much power when you want to discharge,” says Stefanopoulou. “The situation is even more limited when you want to charge.”
Researchers like Stefanopoulou are working on smart solutions to maximize the cold weather coping capacity of cars. If the navigation system is programmed to head to a fast charger, the computer can make sure the battery is nice and warm by the time it arrives there. And in a recent paper, Stefanopoulou suggests a battery could discharge some of its precious energy when it’s cold, to keep itself warm. That sounds counterintuitive when range is already limited, but driving on a cold battery, with high resistance, when current demands to the motors are also high, is more wasteful.