Electric vehicles have come along way. Yes, they are quick, powerful and incredibly environmentally friendly.
But how practical are they, really, given limits on far how they can go on a single charge, especially in Minnesota’s bitter cold winters?
Star Tribune reader Michael Orange, an environmental consultant, posed that question to Curious Minnesota, our community-driven reporting project fueled by great questions from inquisitive readers. His question was selected by readers who voted for it to be answered by us.
The short answer is that cold temperatures do degrade electric vehicles’ performance. Electric vehicles perform at their peak in temperatures between 50 and 80 degrees, when the lithium-ion battery’s power can focus on propelling the vehicle down the road and not be diverted using energy to heat or cool the cabin.
The vehicles perform just as well as their gas-powered counterparts when it comes to traversing through snow and ice, but the cold drains batteries and impacts how far motorists can drive before they need to recharge, said William Northrop, an associate professor of mechanical engineering at the University of Minnesota.
In winter, cold engine oil and idling can drag down fuel economy of even gas-powered vehicles by as much as 20% on short trips, according to the U.S. Department of Energy. But engines also produce extra heat that can be used to heat a cab without diminishing gas mileage. In electric vehicles, there is no extra engine heat, so the battery must heat the cabin, further diminishing the distance motorists can drive.
A recent study by AAA found that electric vehicle owners can expect their driving range to decline by 41% when the mercury dips to 20 degrees. That means for every 100 miles of driving in optimal conditions, the range would drop to 59 miles.
The study also showed some decrease in range when temperatures reach 95 degrees or higher, but the drop is not as severe as in the cold.
Northrop, who drives an electric Volkswagen Golf, said those numbers were kind to Minnesota. He said his range drops by nearly 60% on the coldest of days.
“You just have to think about where you are going to charge,” he said. “If you drove and didn’t turn on the heater, your range would be a lot higher.”
Some 1.2 million plug-in electric vehicles, including those from Nissan, Tesla and Chevrolet, have been sold in the United States, with sales particularly strong in areas such as Los Angeles, San Diego or San Francisco.
But for electric vehicles to be broadly adopted, they must be able to have a consistent range and a charging capability in a variety of conditions, said Anna Stefanopoulou, director of the University of Michigan’s Energy Institute.
Current batteries have other limitations in the cold, too, “namely the reduced ability in accepting charge during [regeneration] braking or even during charging,” she said.
A recent study, she said, showed that when an electric vehicle battery was charged at 77 degrees, the battery got to 80% capacity in 30 minutes, but at 32° F, it was only charged to 44% after the same amount of time.
Low mileage range has been one of the biggest knocks against electric vehicles, although newer models now can get more than 300 miles on a fully-charged battery.
For most drivers, that is plenty. The average driver puts on only 29 miles a day, according to the National Household Travel Survey from the Bureau of Labor Statistics. That’s well within the capabilities of current batteries. And technological advances will make it easier to keep a battery from going dead, Northrop said.
Vehicles like Teslas, and the new Jaguar I-Pace electric, now let owners charge their vehicles from a far with an app.
The number of places to charge is growing, too. Many employers offer charging stations and some parking ramps in Minneapolis have places to plug in. In the future, Northrop said drivers might even be able to park on a pad or drive over a sensor to get the juice they need.
John Smart, with the Idaho National Laboratory, a battery testing center, said manufacturers are addressing the range problem by developing solid state batteries without liquid inside that can hold and store energy, and are less sensitive to cold and heat. Some new generation models are coming with electric heated seats and packs to keep batteries warm for optimal performance.
Northrop said developers also are looking for ways to speed up the charging process, another hurdle for more widespread acceptance.
“Advances are coming so fast. You will see a lot of advances in the coming years,” he said. “In 20 years we won’t be talking about range.”
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