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- Tesla has been accused of overstating its EVs' ranges, particularly in cold weather.
- EV car batteries drain much quicker in cold conditions, significantly affecting their performance.
- The main issue is caused by drivers heating their cabins, a battery expert previously told Insider.
Tesla is facing backlash following a report that says it created a secret team to suppress customer complaints about the range of its electric vehicles.
Reuters reported that the EV maker had created a "diversion team" last summer, which was tasked with canceling as many range-related appointments as possible.
The report says that Tesla received thousands of complaints from customers who were unhappy with their EVs' ranges, highlighting one complaint that said the car was particularly affected by cold weather — an accusation that the company has faced before.
Earlier this year, the automaker was hit with a fine of around $2 million by South Korean regulators after being accused of exaggerating the range of its cars in cold weather.
The Korea Fair Trade Commission said the battery performance of a typical Tesla dropped by around 50% in the cold.
But Tesla isn't the only EV maker to struggle with its range in cold weather.
A study by Recurrent that analyzed thousands of EVs' estimated and verified winter ranges suggested that battery performance in numerous models could drop anywhere between 3% and 32% in freezing conditions when compared to 70-degree weather.
Why EV batteries don't last as long in the cold
Venkat Srinivasan, a battery expert and the director of the Argonne Collaborative Center for Energy Storage Science, told Insider's Tim Levin that the main reason batteries drain more in the cold was drivers heating their cabins.
Whereas gas cars use the heat generated by their engines to warm passengers, electric cars rely solely on battery power. Cooler temperatures also slow the chemical and physical reactions that make batteries work, per Recurrent.
Anna Stefanopoulou, the director of the University of Michigan's Energy Institute, told Wired that batteries were "like humans" and preferred temperatures between 60 and 80 degrees Fahrenheit.
"You don't have as much power when you want to discharge," Stefanopoulou said. "The situation is even more limited when you want to charge."
Charging EV batteries in cold weather
Charging can also be an issue in cold conditions.
The Idaho National Laboratory reported that EV batteries can take up to three times as long to charge in cold temperatures.
Stefanopoulou told Wired that it was important to try and keep EVs charged to at least 20% in subzero temperatures, as the vehicles need to use that charge to warm the battery enough to power up.
In December, Tesla owner and radio presenter Domenick Nati told Insider he tried charging his car in a Tesla Supercharger in 19-degree weather.
But 15 hours later, he said his car only charged to 19 miles and he was forced to cancel his Christmas plans.
Some startups are seeking to make cold weather issues a thing of the past.
Greater Bay Technology, a Chinese firm, told Bloomberg that its new "phoenix" cell can charge from 0% to 80% in six minutes — regardless of the outside temperature.
There are a few ways that drivers of electric vehicles can prolong their cars' battery lives in cold weather. British automotive marketplace Autotrader suggests putting the car into eco-mode, which, where fitted, helps to direct power to where it's needed most and away from features like speakers.
It also suggests drivers keep their EVs under cover when parked to help keep them warmer. The warmer they are, the more likely they are to maintain their charge, it adds.