Alaska’s rugged and frigid interior, where it can get as cold as minus 50 Fahrenheit, is not the place you’d expect to find an electric school bus.
But here is Bus No. 50, quietly traversing about 40 miles of snowy and icy roads each day in Tok, shuttling students to school not far from the Canadian border.
It works OK on the daily route. But cold temperatures rob electric vehicle batteries of traveling range, so No. 50 can’t go on longer field trips, or to Anchorage or Fairbanks.
It’s a problem that some owners of electric passenger vehicles and transit officials are finding in cold climates worldwide.
Some automakers and drivers fear lower battery range in the cold could limit acceptance of electric cars, trucks and buses, at a time when emissions from transportation must go down sharply to address climate change.
Many owners of personal electric vehicles also are finding that long-distance wintertime travel can be hard. EVs can lose as much as 36% of their range as cold spells come at least a few times each winter in many U.S. states.
Some owners, though, didn’t anticipate such a big decline in the winter. Rushit Bhimani, who lives in a northern suburb of Detroit, said he sees about 30% lower range in his Tesla Model Y when the weather gets cold, from what’s supposed to be 330 miles per charge to as low as 230.
Around three-quarters of this EV range loss is due to keeping occupants warm.
The range loss has not slowed EV adoption in Norway, where nearly 80% of new vehicle sales were electric last year.
Recent tests by the Norwegian Automobile Federation found models really vary. The relatively affordable Maxus Euniq6 came the closest to its advertised range and was named the winner. It finished only about 10% short of its advertised 220 mile range. The Tesla S was about 16% percent under its advertised range. At the bottom: Toyota’s BZ4X, which topped out at only 200 miles, nearly 36% below its advertised range.
Recurrent, a U.S. company that measures battery life in used EVs, said it has run studies monitoring 7,000 vehicles remotely, and reached findings similar to the Norwegian test.
CEO Scott Case said many EVs use resistance heating for the interior. The ones that do better are using heat pumps, which draw heat from the outside air in cold temperatures.
Inside batteries, lithium ions flow through a liquid electrolyte, producing electricity. But they travel more slowly through the electrolyte when it gets cold and don’t release as much energy. The same happens in reverse, slowing down charging.
General Motors is among those working on solutions.
Last week, GM sent a squadron of EVs from the Detroit area to Michigan’s chilly Upper Peninsula to test the impact of cold weather on battery range.
Despite stopping to charge twice on the way, a GMC Hummer pickup, with around 329 miles of range per charge, made the 315 mile trip to Sault Ste. Marie with only about 35 miles left, barely enough to reach GM’s test facility.
Neil Dasgupta, associate professor of mechanical and materials science engineering at the University of Michigan, says they’re developing new battery designs that allow ions to flow faster or enable fast charging in the cold. There also are battery chemistries such as solid state that don’t use liquid electrolytes.
He expects improvements to find their way from labs into vehicles in the next two to five years.