For nearly a week, freezing temperatures from Chicago to North Texas have made life difficult for electric vehicle owners as range is limited and they have to wait hours at charging stations.
In Oak Brook, Illinois, near Chicago, television reporters on Monday found Teslas running out of juice while waiting in long lines for power outlets at a Supercharger station. The temperature reached a low of minus 9 Fahrenheit (-23 degrees Celsius).
Outside Ann Arbor, Michigan, Teslas were plugged into six of eight charging stations on Wednesday as the wind howled with a temperature of minus 14 degrees Celsius. At least one driver was almost out of juice.
It is well known that electric vehicles lose some of their range in cold weather, especially in subzero temperatures like those experienced in the middle of the country this week. Studies have shown that the loss of range is between 10% and 36%.
Even in extreme cold, electric vehicles do not charge as quickly. Some Tesla owners near Chicago told reporters that their cars were not charging at all.
Experts acknowledge that cold weather can be difficult for electric vehicles, but say that with some planning and a little adjustment, owners should be able to travel as normal.
WHAT IS THE PROBLEM?
In electric vehicle batteries, lithium ions flow through a liquid electrolyte to generate electricity. However, when it is cold, they migrate more slowly through the electrolyte and do not release as much energy. This reduces the range and can drain the battery more quickly.
The same thing happens in reverse. Because electrons move slower, the battery cannot absorb as much current from a charging plug. This slows down the loading process.
The problem is that as temperatures drop, batteries need to be warm enough for the electrons to move. And at fast charging stations like Tesla's they have to be even warmer.
“Pretty much anything that is a chemical substance slows down when the temperature is low,” said Neil Dasgupta, an associate professor of mechanical engineering and materials science at the University of Michigan. “It’s just something nature gave us and we have to deal with it.”
At a Supercharger station in Pittsfield Township, Michigan, south of Ann Arbor, the battery in Ankita Bansal's Tesla only had 7% of its charge left. She plugged it in, but the car didn't need any power. Instead, the display showed that the battery was heating up. After it reaches the right temperature, it would take an hour and 50 minutes to fully charge, the display said.
“I still have a long way to go,” said Bansal, a graduate student at the University of Michigan who wanted to achieve full charging because she doesn’t have a charging station at home.
HOW IT WORKS
Bruce Westlake, president of the Eastern Michigan Electric Vehicle Association, said most electric vehicles are programmed to warm up the battery when the driver tells the vehicle's navigation system that a trip to the charging station is impending.
Many of those who believe their cars aren't charging are new to electric vehicles and don't know how to “precondition” their batteries, said Westlake, who owns two Teslas.
“They’re just learning,” he said. “And Tesla is not very good at explaining some things.” A message was left seeking comment from Tesla.
In freezing temperatures, it can take half an hour for the battery to warm up and be ready to charge, Westlake said. Preconditioning the battery does cost some range, although it's usually only a few miles, he said.
Bansal, who has only had her Tesla for a week, didn't know how to precondition the car before charging, but now she does.
A few stalls away, Kim Burney's Tesla Model 3 was charging just a little slower than normal temperatures. She had driven further than she thought on a trip to her dentist in Ann Arbor on Wednesday morning and wanted to get close to a full charge for the rest of the day.
So she told the car she was going to the charging station, and when she arrived and plugged it in, it was ready.
Like Westlake, Burney said electric vehicle drivers need to plan ahead, especially in cold weather. The car, she said, will tell you where charging stations are and how much range you have left. “The more you drive it, the more confident you will be in knowing how far you can go and how much you need to charge to do it,” she said.
Burney said she loses about 15 to 20% of her battery range in cold weather, but things get dramatically worse during cold snaps like this week.
THE FUTURE OF THE STORE
In the short term, automakers will likely find better ways to extend battery life and warm them up for charging, Dasgupta said. And there are new battery chemistries in development that are more resilient in cold weather.
In the short term, Dasgupta said that as more mainstream consumers buy electric vehicles and as more automakers enter the market, they will develop models that use existing lithium-ion chemistry and are tailored to colder climates. In some cases, overall range may have to be sacrificed somewhat to achieve better cold-weather performance, he said.
Millions are being invested in new battery technologies that work better in cold temperatures and are making their way from military, aerospace and underwater applications to electric vehicles, Dasgupta said.
“In a cold climate you can drive an electric vehicle,” he said. “Be optimistic and excited about the future because it only gets better from here.”