By TOM KRISHER and MARK THIESSEN
TOK, Alaska (AP) – Alaska’s rugged, icy interior, where it can get as cold as 50 Fahrenheit (minus 46 degrees Celsius), isn’t where you’d expect to find an electric school bus.
But here is bus #50, with a cartoon horse decal on the side, silently traversing some 40 miles of snowy and icy roads every day in Tok, taking students to school not far from the Canadian border.
It works fine on the daily route. But cold temperatures rob EV batteries of range, so the No. 50 can’t take longer field trips, or to Anchorage or Fairbanks.
It’s a problem that some electric passenger vehicle owners and transit workers are encountering in cold climates around the world. At 20 degrees F (minus 7 C), electric vehicles just don’t go as far as the ideal 70 degrees. Part of that is that keeping passengers warm using traditional technology drains the battery.
So longer trips can be difficult in colder weather. Transit authorities like Chicago, which has pledged to convert its entire bus fleet to electricity by 2040, must take extraordinary measures to keep electric buses charged and on schedule.
Some automakers and drivers fear that the shorter battery life in the cold could limit acceptance of electric cars, trucks and buses at a time when transport emissions must drop sharply to cope with climate change. There is hope. Scientists are racing to perfect new battery chemistries that don’t lose as much energy in cold climates as current lithium-ion systems.
Also, cars equipped with efficient heat pumps don’t lose as much range in the cold.
“It’s a problem to have batteries in cold weather, 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, your cost to operate Tok’s electric bus 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 trolley bus drops to about 90 cents a mile when it’s hot, but he says the costs make it impractical and he wouldn’t buy another one.
Many personal electric vehicle owners are also finding that long-distance winter travel can be difficult. EVs can lose anywhere from 10% to 36% of their range as cold spells occur at least a few times each winter in many US states.
Mark Gendregske of Alger, Michigan said it starts to get serious when temperatures drop into the 10-20 F range (minus 7 to minus 12 C). “Typically, I see more than 20% degradation in range as well as charging time,” he said as he recharged his Kia EV6 in the parking lot of a shopping center near Ypsilanti, Michigan. “I go from about 250 miles of range to about 200.”
Gendregske, an engineer at an auto parts manufacturer, knew the range would decrease, so he said with planning, the Kia EV still gets you where you need to go, even with a long commute.
Some homeowners, however, did not anticipate such a large winter decline. Rushit Bhimani, who lives in a suburb north of Detroit, said he sees about 30% less range on his Tesla Model Y when the weather turns cold, from what should be 330 miles per charge to just 230. that one,” he said as he made his way 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 go out of their way to not use too much heat so they can travel further, wearing gloves or sitting in heated seats to save energy.
And, of course, gasoline engines can also lose about 15% of their range in the cold.
The loss of range has not dampened EV adoption in Norway, where nearly 80% of new vehicle sales were electric last year.
Recent tests by the Norwegian Automobile Federation found that models really do vary. The relatively affordable Maxus Euniq6 came closest to its advertised range and was named the winner. It finished only about 10% short of the advertised range of 354 km (220 miles). The Tesla S was about 16% below the advertised range. At the bottom: Toyota’s BZ4X, which only reached 323 kilometers (200 miles), almost 36% below the advertised range.
Nils Soedal of the Automobile Federation calls the issue “not problematic” as long as drivers take it into account when planning a trip. “The big issue is actually having enough charging stations along the road” and better information about whether they are working properly, he said.
(AP Video/Mike Householder/Mark Thiessen)
Temperatures ranged from zero to minus 2.2 F (0 to minus 19 C) during testing, over mountains and along snow-covered roads. Cars were driven until they ran out of juice and stopped.
Recurrent, an American company that measures battery life in used electric vehicles, said it had conducted studies monitoring 7,000 vehicles remotely and reached similar conclusions as the Norwegian test.
CEO Scott Case said that many EVs use resistance heating for the interior. The ones that do best are using heat pumps.
Heat pumps extract heat from outside air even at low temperatures and have been around for decades, but have only recently been developed for automobiles, Case said. “That’s definitely what needs to be on all these cars,” he said.
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 the load.
Neil Dasgupta, an associate professor of mechanical engineering and materials science at the University of Michigan, likens it to spreading cold butter on toast. “It becomes more resistant at low temperatures,” said Dasgupta.
General Motors is among those working on solutions. By testing, engineers can make changes to battery and heat management in existing cars and learn for future models, said Lawrence Ziehr, project manager for energy recovery in GM electric vehicles.
Last week, GM sent a squadron of Detroit-area EVs into Michigan’s frigid Upper Peninsula to test the impact of cold weather on battery range.
Despite stopping to charge twice along the way, a GMC Hummer pickup truck, with about 329 miles of range per charge, made the 315-mile trip to Sault Ste. Marie with only about 35 miles left, just enough to get to GM’s test facility. After finding a faulty charging station at a grocery store, engineers went to a nearby hotel to get enough juice to finish their trip.
At universities, too, scientists are working on chemical changes that could make cold-weather loss a thing of the past.
Dasgupta at the University of Michigan says he’s developing new battery designs that allow ions to flow faster or charge faster in the cold. There are also battery chemistries such as solid state that do not use liquid electrolytes.
He expects the improvements to make their way from labs to vehicles over the next two to five years.
“There really is a global race to increase the performance of these batteries,” he said.
David Keyton contributed from Stockholm, Sweden. Krisher reported from Chicago and Sault Ste. Mary, Michigan.
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