Alaska’s harsh and frigid interior, where it can get as cold as minus 50 Fahrenheit (minus 46 degrees Celsius), isn’t where you’d expect an electric school bus to be.
But here’s the #50 bus with a cartoon horse sticker on the side that quietly traverses about 40 miles of snowy and icy roads every day in Tok, taking students to school not far from the Canadian border.
On the day route it works perfectly. But cold temperatures rob electric vehicle batteries of range, preventing No. 50 from taking longer field trips or to Anchorage or Fairbanks.
It’s a problem found by some electric passenger vehicle owners and traffic officials in cold climates around the world. At 20 degrees F (minus 7 C), EVs just don’t go as far as they do at the ideal 70 degrees. Part of this is that keeping passengers warm with conventional technology drains the battery.
As a result, longer rides in the coldest weather can be difficult. Transportation authorities like Chicago, which have committed to electrifying their entire bus fleet by 2040, must take extraordinary steps to keep electric buses charged and on schedule.
Some automakers and drivers worry that reduced battery range in the cold could limit the uptake of electric cars, trucks and buses at a time when emissions from transport must be sharply cut to counteract climate change. There is hope. Scientists are racing to perfect new battery chemistries that don’t lose as much energy in cold weather as today’s lithium-ion systems.
In addition, cars equipped with efficient heat pumps do not lose as much range in the cold.
“Having batteries in cold weather is a problem, and we have a pretty cold climate, one of the coldest in North America,” said Stretch Blackard, owner of Tok Transportation, which contracts with local schools.
When the temperature drops to zero, his cost of running Tok’s Electrobus doubles. Tok has one of the highest electricity prices in the country.
In the coldest weather, 0 to minus 10 F (minus 18-23 C), the electric bus costs about $1.15 per mile, versus 40 cents per mile for a diesel bus, Blackard said. The cost of the electric bus drops to about 90 cents a mile when it’s warm, but he says the cost makes it useless and he wouldn’t buy another one.
Many private electric vehicle owners are also finding that long-distance travel can be difficult in winter. EVs can lose anywhere from 10% to 36% of their range as many US states experience at least a few cold snaps each winter.
Mark Gendregske, of Alger, Michigan, said things start to get serious when temperatures drop to the 10 to 20F (minus 7 to minus 12C) range. “I typically see more than a 20% decrease in range and charge time,” he said while charging his Kia EV6 in a mall parking lot near Ypsilanti, Michigan. “I’m going from about 250 miles of range to about 200.”
Gendregske, an engineer for an auto parts maker, knew range would drop, so he said that with planning, the Kia EV will still get him where he needs to go, even on a long drive.
However, some owners did not expect such a large drop in winter. Rushit Bhimani, who lives in a northern Detroit suburb, said he sees about 30% less range in his Tesla Model Y when the weather turns cold, from a reported 330 miles per charge to just 230. “They should clarify this one.” , he said while rushing south from Ann Arbor on a trip to Chicago.
About three-quarters of that EV range loss is due to keeping occupants warm, but speed and even highway driving are factors. Some drivers try very hard not to use a lot of heat so they can keep driving, wear gloves or sit in heated seats to conserve energy.
And of course, petrol engines can also lose around 15% of their range in the cold.
The loss of range hasn’t slowed EV adoption in Norway, where nearly 80% of new car sales last year were electric.
Recent testing by the Norwegian Automobile Association revealed that the models really do vary. The relatively inexpensive Maxus Euniq6 came closest to the advertised range and was crowned the winner. It ended up only about 10% short of its advertised range of 354 km (220 miles). The Tesla S was about 16 percent short of its advertised range. Bottom: Toyota’s BZ4X, which was almost 36% short of the advertised range at just 323 kilometers (200 miles).
Nils Soedal from the Automobile Association calls the issue “unproblematic” as long as drivers take it into account when planning their trip. “The big problem really is getting enough charging stations along the road,” and better information on whether they’re working properly, he said.
Temperatures ranged from just zero to minus 2.2 F (0 to minus 19 C) over mountains and along snow-covered roads during testing. The cars were driven until they ran out of juice and stopped.
Recurrent, a US company that measures battery life in used electric vehicles, said it conducted studies remotely monitoring 7,000 vehicles and got results similar to the Norwegian test.
CEO Scott Case said many electric vehicles use resistance heating for the cabin. Those that do better use heat pumps.
Heat pumps extract heat from outside air even in cold temperatures and have been around for decades, but they were only recently developed for cars, Case said. “It definitely has to be in all these cars,” he said.
In batteries, lithium ions flow through a liquid electrolyte, generating electricity. But they migrate more slowly through the electrolyte when it gets cold and don’t release as much energy. The same thing happens in reverse, slowing down the loading process.
Neil Dasgupta, associate professor of mechanical engineering and materials science at the University of Michigan, likens it to spreading cold butter on toast. “It just becomes more resilient at low temperatures,” Dasgupta said.
General Motors is working on solutions, among other things. Through testing, engineers can make battery and thermal management changes in existing cars and learn for future models, said Lawrence Ziehr, GM’s electric vehicle energy recovery project manager.
Last week, GM sent a squadron of electric vehicles from the Detroit area to Michigan’s cool upper peninsula to test the cold weather’s effects on battery range.
Though he stopped twice for recharges along the way, a GMC Hummer pickup with a range of around 329 miles 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. After discovering a broken charging station at a grocery store, engineers went to a nearby hotel to get enough juice to complete the trip.
Scientists at universities are also working on chemical changes that could make cold losses a thing of the past.
The University of Michigan’s Dasgupta says they are developing new battery designs that allow ions to flow faster, or allow for quick charging in the cold. There are also battery chemistries such as solid state batteries that do not use liquid electrolytes.
He expects improvements to make their way out of the lab and into vehicles over the next two to five years.
“There really is a global race to improve the performance of these batteries,” he said.
David Keyton contributed from Stockholm, Sweden. Krisher reported from Chicago and Sault Ste. Marie, Michigan.
The Associated Press’s climate and environmental reporting is supported by several private foundations. Learn more about AP’s climate initiative here. The AP is solely responsible for all content.