Global race to extend electric vehicle range in cold weather

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

But here’s the No. 50 bus, with a cartoon horse decal on its side, that quietly traverses about 40 miles of snowy and icy roads each day in Tok, taking students to school not far from the Canadian border.

On the daily route it works fine. But cold temperatures rob electric vehicle batteries of travel range, so No. 50 can’t take longer excursions, whether to Anchorage or Fairbanks.

It’s a problem faced by some electric passenger car owners and transportation officials worldwide in cold climates. At 20 degrees F (minus 7 C), electric vehicles just don’t go as far as they would at the ideal 70 degrees. Part of that is that keeping passengers warm with traditional technology drains the battery.

So longer trips can be difficult in the coldest weather. Transportation authorities like Chicago’s, which have pledged to convert their 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 reduced battery range in the cold could limit the adoption of electric cars, trucks and buses, at a time when transport emissions need to drop sharply to tackle climate change. There is hope. Scientists are racing to perfect new battery chemistries that don’t lose as much energy in cold weather as current lithium-ion systems.

Also, 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 has contracts with the local schools.

When the temperature reaches zero, his cost to run 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 electric bus drops to about 90 cents a mile when it’s hot, but he says the cost makes it unworkable and he wouldn’t buy another one.

Many personal electric vehicle owners also find that long-distance travel in the winter can be difficult. EVs can lose between 10% and 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 things start to get serious when temperatures drop to 10-20 F (minus 7 to minus 12 C). “I usually see more than 20% degradation in range and charge time,” he said as he charged his Kia EV6 in a shopping center 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 the range would drop, so he said the Kia EV, with planning, will still get him where he needs to go, even with a long trip.

However, some owners did not expect such a large decline in winter. Rushit Bhimani, who lives in a northern suburb of Detroit, said he sees about a 30% reduction in range in his Tesla Model Y as it gets colder, from what is believed to be 330 miles per charge to as low as 230. That,’ he said as he attacked just south of Ann Arbor on a trip to Chicago.

About three-quarters of this EV range loss is due to keeping occupants warm, but speed and even highway driving are factors. Some drivers go to great lengths not to use much heat so they can travel farther, wear gloves or sit in heated seats to save energy.

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

The loss of range has not slowed EV adoption in Norway, where nearly 80% of new vehicle sales last year were electric.

Recent tests by the Norwegian Automobile Federation have shown that the models differ greatly. The relatively affordable Maxus Euniq6 came closest in its advertised range and was declared the winner. It ended up being only about 10% short of the advertised range of 354 km (220 mi). The Tesla S was about 16% percent below the advertised range. Bottom: Toyota’s BZ4X, with a top speed of just 323 kilometers (200 mi), nearly 36% below its advertised range.

Nils Soedal, of the Automobile Federation, calls the problem “unproblematic” as long as drivers take it into account when planning a trip. “The big problem really is getting enough roadside charging stations,” 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 snowy roads. The cars were driven until they ran out of juice and stopped.

Recurrent, a US company that measures the lifespan of used electric cars, said it has conducted studies to remotely monitor 7,000 vehicles and has reached findings similar to the Norwegian test.

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

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

In 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 thing happens in reverse, slowing down the charging.

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

General Motors is one of those working on solutions. Testing allows engineers to make changes to battery and thermal management 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 impact of cold weather on battery range.

Despite stopping twice along the way to charge, a GMC Hummer pickup, with a range of approximately 529 miles per charge, made the 515-mile journey to Sault Ste. Marie with only about 35 miles to go, barely enough to make it to GM’s testing facility. After finding a faulty charging station at a grocery store, engineers headed to a nearby hotel to get enough energy to complete the journey.

Scientists at universities are also working on changes in chemistry that could make loss due to cold 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 charge quickly 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 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. Mary, Michigan.

___

The Associated Press’ climate and environmental coverage is supported by several private foundations. Read more about AP’s climate initiative here. The AP is solely responsible for all content.