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It’s common knowledge that electric vehicles lose range when temperatures plummet. But if you’re wondering whether EVs are also slower to charge in cold weather, look no further than the parched fine print of a recent Toyota press release: “For the bZ4X AWD model, charging may slow down more than other models in weather conditions below 32 degrees Fahrenheit [zero degrees Celsius] and may not be possible when the temperature drops to around -4 degrees Fahrenheit [-20 degrees Celsius] and below.”

Not all auto makers are as forthcoming as Toyota. Subaru’s new all-electric Solterra shares a platform with the bZ4X, but the auto maker is tight-lipped about its cold-weather performance. “While the Subaru Solterra is expected to launch later this year, we are unable to provide more information at this time,” wrote Sebastien Lajoie, a spokesman for Subaru Canada.

Asked about the new Nissan Ariya’s cold-weather charging limitations, a company spokeswoman provided a similar response: “We are not able to comment on this since Nissan does not publish such data,” Rachel Jaskula wrote.

Hyundai acknowledged the issue in the Ioniq 5. “The Ioniq 5 charging rate does slow down, as do all EVs in cold conditions. However, we implement battery heating in Ioniq 5 in the Canadian market, so we can still charge the vehicle even below -4F,” said Jennifer McCarthy, national manager of public relations at Hyundai Canada.

Offering clarification of Toyota’s disclaimer, Philippe Crowe with Toyota Canada said that if the battery itself is kept warmer than minus 20 degrees Celsius – such as with the use of an AC charger, or not leaving the vehicle outdoors for long periods of time without a charge – that will help, and the owner will still be able to charge quickly with DC fast charging.

But for some EV drivers, that may be less than ideal.

“If you’re charging below zero, the charging process will be very, very lengthy,” said Moataz Mohamed, an assistant professor of civil engineering at McMaster University in Hamilton.

“Below zero degrees Celsius, you can’t just plug in an EV and have power immediately in your battery. There are multiple stages to charging a lithium-ion battery. … In the first phase, you’re actually transferring that electricity into heat to heat the battery and then the battery will start accepting or storing energy,” he said. That energy used to heat the battery pack results in a loss of range and longer charging times.

A cold battery could mean double the charge time, said Lawrence Ziehr, project manager of General Motors’ Ultium Energy Recovery Systems in Clarkson, Mich. To combat this issue, which affects Chevrolet’s Bolt, the car maker now uses a system to precondition or warm the battery on some models, which allows charging times to remain just as fast.

The new Ultium Battery platform is in its latest EVs, including the GMC Hummer and Cadillac Lyriq. The Bolt won’t have it, but all other models will. The company took lessons from the Bolt, Ziehr said. “We need to do this better.”

Preheating the battery can be done on many EVs – some cars use a connected services app, which lets you warm up the battery and cabin before stepping into your vehicle, all through your cellphone.

Not only does cold weather increase charging times; it also reduces range. If your car is parked outside for days in minus 20 degrees Celsius weather, “you can see half of your [range] capacity start to drop,” Ziehr said. But it’s not gone for good. “The energy is still there, but you just can’t get it out of the battery because of the temperature.” He said as the battery warms, drivers will see ranges start to increase.

According to a recent study from Recurrent, a Seattle-based battery analysis company, all EVs lose some range in cold weather. Of the 13 EVs studied, the range dropped by an average of 10 per cent to more than 30 per cent. That’s largely because the chemical reactions that the lithium-ion batteries rely on happen more slowly and the climate control is much less efficient in an EV than in a traditional internal combustion engine, said Liz Najman, climate scientist and communications manager at Recurrent.

“When you’re driving a conventional gasoline car, the engine produces a lot of heat waste. Touch the hood of a car and you can feel it’s really hot. Basically, the car keeps all of that energy and that extra heat flows into the cabin so you get heating for free,” Najman said.

“In an electric vehicle, the electric motors are very efficient. They don’t have a lot of heat waste, and so the battery has to generate a lot of heat, and that draws from the same source that you are getting your range from.”

Based on Recurrent’s research, the most efficient EV in cold weather was the Tesla Model Y Long Range AWD SUV, which reached 98 per cent of its original estimated range in minus one to minus six degrees Celsius. The Model Y uses a new, more energy-efficient heat pump system to regulate temperatures without drawing from the high-voltage battery.

The least efficient EV was the Ford Mustang Mach-E Premium AWD model, which achieved 65 per cent of its range in minus one to minus six degrees C. While the Mach-E has an app to warm the battery, it doesn’t have a heat pump, so energy is taken from the battery to create heat, which reduces range.

The Chevrolet Bolt, which also doesn’t have a heat pump, achieved 66 per cent of its original range, as estimated by the U.S. Environmental Protection Agency.

Based on Mohamed’s studies, heavy-duty EVs lose between 16 and 22 per cent of range based on climate control settings, road conditions and the internal temperature of the battery. “This is the Achilles' heel for electric vehicles,” he said. In cold temperatures, he advises using a plug-in block heater when parked or a smart charger, so if you need your car at a specific time, the system will optimize the amount of energy used to make sure it’s ready.

For manufacturers he recommends ditching fuel-consumption-equivalent data and replacing it with a multi-tiered system designed to accurately reflect range in an EV.

“We shouldn’t use the same approach for EVs because it’s not about highway or urban. It’s the opposite. If you drive in stop-and-go traffic, you are gaining a lot of power from the regenerative braking system,” said Mohamed. Instead, car makers should provide three key figures for EVs: summer performance data with air conditioning, winter performance data with heating, and full performance data with no air conditioning or heating. Then drivers will be able to make an informed decision about whether the EV fits their lifestyle.

In cold weather, Recurrent’s Najman recommends using seat warmers and steering wheel warmers instead of climate controls through air vents, charging immediately after a trip when the battery is warm, and ensuring that whatever vehicle you buy has a heat pump to generate heat with less draw on the battery.

On the bright side, she said, the range loss and slower charging times in cold weather are temporary and won’t harm the battery. “Your range should return as soon as the weather thaws out.”

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