Lithium-ion batteries face cold-weather challenge

It’s been the winter of Chicago’s discontent. Amid bone-chilling cold in January, electric vehicles got a taste of winter reality.

Charging cars became next to impossible. One Tesla driver who had been waiting in line was at a Chicago area station for five hours told CBS News that “a charge that should take 45 minutes is taking two hours.”

It turns out that the lithium-ion batteries that charge EVs are susceptible to very cold weather.

Though Tesla got the blame, it turned out to be just about any EV. That’s because lithium-ion batteries are the current standard of the EV industry. Chevy Bolt drivers also reported issues. Car & Driver magazine lists 20 EVs models for sale in 2024, including versions of Ford F150, Chevy Blazer and Hummer, all of which use the batteries.

Lithium-ion batteries are actually used in everything from smartphones to EVs. For electric vehicle opponents, the Chicago problem was a chance to seize on another perceived vulnerability of EVs and especially Tesla, which leads EV sales in the U.S., selling 55% of all those sold last year.

The battery issue has become another bump in the road for a government push to have EVs or hybrids take over roads in the coming years. Demand has dropped off a bit and plans have had to be adjusted. That’s led President Joe Biden’s administration to slow the plan to have 50% of cars on the road be electric by 2030.

“Tesla has been politicized and a lot of what the consumers of news get is not always true or perhaps is slanted to discourage people from considering an EV,” said local Tesla owner Dennis Spanogle. “That is unfortunate.”

He added that Tesla does a good job of battery maintenance as well as the other EV makers.

Tesla has practical guidelines for dealing with the type of freeze experienced in Chicago and elsewhere: Keep the car plugged in and maintain a charge of at least 20%, for example.

But the problem may be the battery itself, experts say.

Wesley Chang, a mechanical engineering professor at Philadelphia’s Drexel University said lithium-ion batteries aren’t perfect. His research is centered around making batteries operate more efficiently in the cold.

Writing in The Conversation, an independent news organization, Chang details the inner workings of lithium-ion batteries by using descriptions that non-technical people can understand.

Essentially, they work like this: First off, lithium is the lightest metal, Chang said, and that means it can store a huge amount of charge per weight and that’s why lithium-ion batteries are used, not just in EVs, but also for portable electronics.

The ion part of lithium-ion batteries is the key to how they work. Ions are atoms that have either a negative or positive charge. That is how electricity is stored in batteries. When you plug in your car, the electricity you’re using is what wakes up those ions. The ions are driven from the battery’s positive electrode to its negative electrode. The stored ions in the negative electrode move back to the positive electrode. That movement is what powers the motor.

So why does cold affect them? Well, there’s cold and there’s bitter cold, the latter a Chicago staple. That bitter cold can slow the inner workings of batteries.

Jim DesJardins, executive director of the Renewable Energy Industries Association of New Mexico, says he’s no expert on the inner workings of lithium-ion technology, but he does know Chicago winters.

“I’ve had an EV for 5½ years,” he said. “And I’ve lived in Chicago before. I can speak to the weather.”

In January during the battery charging fiasco, Chicago experienced subzero temperatures.

“It can feel really cold at that time of the year,” DesJardins said. “A lot of vehicles are going to have trouble in that kind of temperature.”

That’s EV or not EV. Spanogle agrees.

“Internal combustion engine cars and trucks use block heaters (for their batteries) in extremely cold weather,” he said.

Engineeer Abbas Akhil, an expert in battery technology and microgrids and a former New Mexico state representative and Sandia engineer, said even here in the Southwest, winter temperatures can be challenging to EV batteries and could be a drawback if drivers do not follow proper procedures.

“It’s understanding the limitations and understanding what the features of the car are,” said Akhil, who is also a board member of Tesla Owners Club of New Mexico. “These batteries, when they are abused, they’ll fail.”

Akhil pointed to one important term drivers need to understand: Battery conditioning, which he says refers to warming the battery during cold conditions. That prewarming is critical for proper functioning, even in conditions that are not super cold. And Tesla’s software is dedicated to keeping good data on battery usage.

“There’s a preconditioning option built into the battery, which basically is just a heater for the battery ... and it brings the battery to the optimal temperature for that particular condition on that day. What the car does is it says, ‘Alright if you want to drive, I’m going to take away some of the charge to warm up the battery first.’”

In other words, it’s a good idea on cold days to check on the battery’s need for preconditioning before setting out on a journey.

That can confuse drivers who charge their battery only to find out the range has suddenly dropped once they hit the road.

In that scenario, if drivers “persist in running the heater or driving faster in very cold weather, that mileage will keep going down very rapidly,” Akhil said.

Compared to some other EVs, he said, Tesla’s software-monitoring of all things in the vehicle is advanced.

“The battery senses a lot of things: How fast you’re driving, how you’re draining the battery, what current it is pulling, all that, that tells the software to say, all right, you’re 17 miles away from the supercharger, so start warming the battery.”

On very cold days, if your car is parked in the garage and it’s minus 15 degrees outside, then people should know to precondition the battery. Conversely, if the battery is already warm, the preconditioning will not start, Akhil said.

“It’s just an energy balance basically. Whatever the car does, it always tries to protect the battery.”

Chang says he and his team are investigating new types of batteries. He mentions sodium-ion batteries as a possibility or solid-state batteries, which aren’t flammable, but he admits they don’t work as well as lithium-ion batteries.

Improvements, innovations and more efficiency, however, are mostly focused on the production process and how tightly the quality can be controlled, Akhil said. Even small defects during the manufacturing process can cause the battery to short out and lead to a fire, he said.

“With 6,000 cells in a Tesla battery, slightly larger than an AA cell, the process to consistently guarantee quality is difficult,” Akhil said.