Global race to increase the range of electric vehicles in cold weather

TOK, Alaska (AP) — Alaska’s rugged and frigid interior, where it can get as cold as minus 50 Fahrenheit (minus 46 Celsius), is not the place you’d expect to find an electric school bus.

But here is bus No. 50, with a cartoon horse decal on the side, quietly traversing some 40 miles of snow-covered and icy roads every day in Tok, transporting students to school not far from the Canadian border.

It works OK on the daily route. But cold temperatures rob electric vehicle batteries of range, so the No. 50 can’t go on long field trips, or to Anchorage or Fairbanks.

It’s a problem some electric car owners and transit officials are finding in cold climates around the world. At 20 degrees F (minus 7 C), electric vehicles don’t go as far as they do at the ideal 70 degrees. Part of that is that keeping passengers warm using traditional technology drains the battery.

So longer walks can be difficult in the coldest weather. Transit authorities like Chicago’s, which has pledged to convert its entire bus fleet to electricity by 2040, must take extraordinary steps to keep electric buses charged and running.

Some car manufacturers and drivers fear that lower battery range in the cold could limit the acceptance of electric cars, trucks and buses, at a time when emissions from transport must fall sharply to meet 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.

Furthermore, 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 the local schools.

When the temperature reaches zero, his cost to drive Tok’s electric bus doubles. Tok has among the highest electricity prices in the country.

In the coldest weather, 0 down to minus 10 F (minus 18-23 C), the electric bus costs about $1.15 per mile, compared to 40 cents per mile for a diesel bus, Blackard said. The cost of the electric bus drops to about 90 cents per mile when it’s hot, but he says the cost makes it useless and he wouldn’t buy another one.

Many owners of personal electric vehicles also find that long-distance journeys in winter can be difficult. Electric vehicles can lose anywhere from 10% to 36% of their range as cold spells arrive at least a couple of times each winter in many US states.

Mark Gendregske of Algiers, Michigan, said it starts to get serious when temperatures drop to the 10-20 F (minus 7 to minus 12 C) range. “I typically see more than 20% degradation in range as well as charging time,” he said while charging his Kia EV6 in a shopping center parking lot near Ypsilanti, Michigan. “I go from about 250 miles of range to about 200.”

Gendregske, an engineer for an auto parts maker, knew range would drop, so he said with planning, the Kia EV still gets him where he needs to go, even with a long commute.

However, some owners did not foresee such a large decrease in winter. Rushit Bhimani, who lives in a northern suburb of Detroit, said he sees about 30% lower range in the Tesla Model Y when the weather turns cold, from what is supposed to be 330 miles per charge to as low as 230. “They should clear it up,” he said as he charges just south of Ann Arbor on a trip to Chicago.

About three-quarters of this EV range loss is due to keeping passengers warm, but speed and even highway driving are factors. Some drivers go to great lengths to avoid using a lot of heat, so they can travel longer, wear gloves or sit on heated seats to save energy.

And to be sure, petrol engines can also lose around 15% of their range in the cold.

The loss of range has not slowed down the use of electric cars in Norway, where almost 80% of new vehicle sales were electric last year.

Recent tests by the Norwegian Automobile Association have found that the models vary greatly. The relatively affordable Maxus Euniq6 came closest to its advertised range and was named the winner. It finished only about 10% short of its advertised range of 354 km (220 mi). The Tesla S was about 16% percent below the announced range. Bottom: Toyota’s BZ4X, which topped out at just 323 kilometers (200 miles), nearly 36% short of its advertised range.

Nils Soedal, from the Swedish Automobile Association, calls the problem “unproblematic” as long as drivers take it into account when planning a trip. “The big issue is really getting enough charging stations along the road,” and better information about whether they’re working properly, he said.

Temperatures ranged from just below freezing to minus 2.2 F (0 to minus 19 C) during the test, over mountains and along snow-covered roads. The cars were driven until they ran out of juice and stopped.

Recurrent, a US company that measures battery life in used electric cars, said it has run studies monitoring 7,000 vehicles remotely and reached findings similar to the Norwegian test.

CEO Scott Case said many electric cars use resistance heating for the interior. Those who do better use heat pumps.

Heat pumps draw heat from the outside air even in cold temperatures, and have been around for decades but have only recently been developed for cars, Case said. “It’s definitely what needs to be in all these cars,” he said.

Inside batteries, lithium ions flow through a liquid electrolyte and produce 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 charging.

Neil Dasgupta, associate professor of mechanical and materials science at the University of Michigan, compares this to spreading cold butter on toast. “It just becomes more resistant at low temperatures,” Dasgupta said.

General Motors is among those working on solutions. By 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 cars from the Detroit area to Michigan’s chilly Upper Peninsula to test the effect of cold weather on battery range.

Despite stopping to charge twice along the way, a GMC Hummer pickup, with about 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 testing facility. After finding a charging station out of order at a grocery store, engineers went to a nearby hotel to get enough juice to complete the trip.

Also at universities, researchers are working on chemical changes that could make the loss of cold weather a thing of the past.

Dasgupta of the University of Michigan says they are developing new battery designs that allow ions to flow faster or enable rapid charging in the cold. There are also battery chemistries such as solid state that do not use liquid electrolytes.

He expects improvements to make their way from labs to vehicles within the next two to five years.

“There really is a global race to increase the performance of these batteries,” he said.

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David Keyton contributed from Stockholm, Sweden. Krisher reported from Chicago and Sault Ste. Marie, Michigan.

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