Tesla Has A Temperature Problem

Originally published by Forbes on Mar 19, 2021

Tesla Model 3 compact sedan. (Photo by Sjoerd van der Wal/Getty Images)

For starters, let me just say I love my Tesla. It’s a white on white leather interior sports car turned suburban sedan. Driving it feels like being picked up by Richard Gere on Hollywood Boulevard — except that you’re making the car payments. To put it bluntly, the Tesla Model 3 makes our family BMW feel like a tin can Chevy Chase station wagon. And sure, it’s better for the planet.

So it’s rather unfortunate that our winter weekend road trip turned out to be such a disaster.

We drove from New York to Vermont, where the state slogan should be “Because you can drive here.” It’s an easy, breezy 184 mile drive via the Taconic State Parkway. It’s so easy, in fact, we didn’t think to check if our destination had a supercharger because we just assumed there would be one reasonably close by. Mistake #1. And we start off with a “full tank”—i.e. 100% charge with a 322 mile range, so we think we’re golden. Mistake #2.

One hundred miles into the journey, we should be at about 222 miles, but it reads 160. Where’s the missing 62 miles? I don’t know, but I’ve got a baby in the backseat who doesn’t fully appreciate the complex nuance of battery technology, or the fact that we need to charge up but there isn’t a supercharger within 40 miles of our destination. Which, by the way, is Vermont, not North Dakota.

So we took a detour to the nearest Supercharge station in Lee, Massachusetts. Meanwhile, the temperature has dropped to minus 2 Farenheit. When it’s this cold, a snow icon appears next to your battery icon on your touchscreen display, as if you weren’t already aware of the creeping frostbite in your fingers. After a 20 minute charge session, we arrived in Manchester with 150 miles left. Seems safe, right? Wrong. Parked outside overnight in what is now negative 8 Fahrenheit, the battery lost 30 miles. Because the cold saps the battery.

In industry parlance, they call this “low temperature performance.”

A Multibillion Dollar Problem

Why does cold weather damage performance this badly in a Tesla, the world’s electric-car leader with a market cap of more than $673 billion (more than all U.S. automakers combined)? And how can this happen in the United States, which federally funds some of the best early-stage battery research in the world? Really, how can this happen to a modern, microprocessor controlled, lithium-ion battery at all? Especially given that the entire auto industry is amid its biggest transformation in a century, investing billions in bids to overtake Tesla (NASDAQ: TSLA)?

It all comes down to the basic function of a regular old every day battery, something we cell phone addicts take for granted.

“Ions are traveling inside of the battery between the positive and negative electrodes through a liquid electrolyte. As it gets colder, the liquid becomes thicker, now closer to freezing solid. So the ions move more slowly, which causes more resistance. The more the resistance goes up, the faster you lose power,” says Greg Less, Ph.D. He’s the technical director at the UM Battery Lab in Ann Arbor, Michigan. The automotive industry uses his facility to build batteries to scale and test new ideas for inclusion in electric vehicles.

Modern batteries have been optimized for the least amount of resistance possible, but that obviously doesn’t help us in a polar vortex. In a car battery, you don’t want to constrict the flow of ions in any way, which means you don’t want to be driving in freezing cold weather. 

“You have to keep the battery warm, but the battery itself is where heat comes from. You’re draining the battery to operate a heater,” adds Less. “You can definitely engineer around temperature problems, but can you do that and still have the same mileage prediction you had when you left the garage? The answer is no.”

Think about it like regular gas mileage. Say your car sticker says you get 25 miles per gallon, but in reality, you’re getting maybe 10. Maybe you accelerate fast or let the car idle. If you follow the rules of getting the best gas mileage, the best you can get is 25 miles to the gallon, but nobody wants to hear that. It's the same with electric vehicles. They’re going to tell you what your ‘maximum range” is fully charged (322 miles in the case of my 2020 Model 3), without calculating environmental conditions. 

For the record, Tesla released a software update slated for April 12, 2021, with this note: “Minor Cold Weather Improvements and Bug Fixes.” It offers no details about what the improvements will be, which strikes freezing New Yorkers as very Palo Alto. What we know for sure is that the words “weather,” “temperature” and “freezing” do not appear anywhere on the MODEL 3 Long Range AWD car sticker. Rather, the tiny print on the bottom right corner of the sticker reads: 

“Actual results will vary for many reasons, including driving conditions and how you drive and maintain your vehicle.” Gee, was that written by a corporate lawyer? It might as well say: We bear no responsibility for anything that happens, ever — especially not mucking up your weekend road trip to Vermont. (Tesla did not respond to requests for comment).

By day three, with no time to snowshoe, see a moose, or make maple pancakes, I had to drive a nerve wracking 40 miles with a supposed 96 miles of charge on the car, only to arrive at the Supercharger with just 20 miles to spare. That roundtrip took three hours. After a year quarantining, do you want to give up your precious Saturday to charge a battery? I think not. Needless to say, I’ve completely sworn off maple candy, flannel pajamas, and winter weekends in electric vehicles unless and until the self-proclaimed “Technoking of Tesla” improves his batteries and there are as many Superchargers as there are gas stations in this electric land of plenty. 

My reaction is precisely what EV car companies, and anyone who believes in our electric-powered future, want to avoid. “How do we convey this to people, and not scare them away from EVs?” asks Less. “Tempering expectations also tempers excitement about transitioning to electric transportation. It’s a fine line to walk.”

Some Good News

Extreme temperatures have never been good for batteries. It’s why we don’t leave our cell phones baking in the sun. But we’re also talking about car safety. 

“Users do have to take precautions when the weather is extremely cold. But do not consider this technology as a static tech. Lots of scientists are trying to resolve this, and it will improve,” says battery expert Shirley Meng, Professor of NanoEngineering and Materials Science at the University of California San Diego.

Meng is a stakeholder in South 8 Technologies, which has developed a “Liquefied Gas Electrolyte” chemistry for rechargeable and primary lithium batteries. The company claims the altered properties of this electrolyte enable a wider operating temperature range of -80 to +60 °C. However, creating a material solution and producing it on a mass scale are two very different challenges. “Our timeline to deliver commercial batteries is next year (2022), though I cannot give a promise when it will be widely used,” adds Meng. 

Lucid Air by Lucid Motors. Courtesy Lucid Motors.

Enter Lucid Motors

It’s a race to the commercial finish line, as almost every electric auto company today claims to invest in battery chemistry research and development. An of-the-moment example is electric vehicle firm Lucid Motors, which last month announced its plans to go public at a $11.75 billion valuation, via a special purpose acquisition company called a SPAC. It's the largest SPAC transaction involving an EV company.

Lucid is partnering with a Korean company called LG Chem, which is testing new anode chemistries and architectures that might support faster charging and better temperature performance. “There’s a lot of research going on in a higher silicone content in the anode, and all that stuff is absolutely relevant. We’ve also just kicked off our own battery research group in house, and we’re really going to push for these architectural improvements,’ says Lucid CEO Peter Rawlinson, who is a former Tesla engineering executive.

He’ll now have to compete with Tesla’s “Tabless” cell, which debuted in September last year. The tabless design means electrons have less distance to flow within the cell— flowing axially rather than circumferentially — thereby reducing the direct current resistance (DCR). At the time, Tesla claimed these new cells will give the company’s batteries five times more energy capacity, and enable a 16 percent range increase for its vehicles... We’re still waiting. The Tabless cell has not yet been implemented in any new models, but Tesla said it intends to incorporate them into the new Model Y in 2021.

“We need to advance the batteries, and we need to work on efficiency. Those two things are equally important,” adds Rawlinson. “If Tesla can advance the Tabless design, and reduce the internal resistance of the cell, I think that will be a real benefit to mankind.”