On a chemical level, heat is like heart disease or a slow-growing form of cancer to an electric car battery
Take it ironically or even slightly poetically: electric cars, which are an ideal means of combating climate change, cannot withstand extremely high temperatures. This is a paradox that occurs at a time when many American states are being burned by heat waves that are becoming more frequent and more intense, writes Bloomberg.
High temperatures are not the kryptonite of battery-powered vehicles. An electric car in a hot climate will work harder to keep the battery and its passengers from heating up, but it won’t have a problem functioning. On a chemical level, however, heat is like heart disease or a slow-growing form of cancer to an electric car battery.
The reason is that when the temperature rises, the ions in the car battery accelerate. Once this happens, they often have trouble attaching to the anode or cathode. Pressure and speed can also create small cracks that slow down chemical reactions and lead to shorter battery life.
To some extent this happens with every fast charge cycle. Using Tesla’s supercharger will move the ions faster than plugging into a wall outlet, and the heat generated by fast charging is one reason smartphone batteries aren’t faster. But on extremely hot days, the ions in an electric car’s battery move even when the car is parked or unplugged, and this can lead to an irreversible reduction in range.
“The worst-case scenario is a car sitting in an unrefrigerated garage in Phoenix all summer without being plugged into a charger,” says Scott Case, co-founder and CEO of Recurrent, a startup that produces battery health reports for customers and electric vehicle dealers. “That will fry the battery very quickly.” If the car is plugged into a charger, it will use the energy to cool its battery.
Very cold weather can also have adverse effects on a car battery. The colder it is, the slower the chemical processes happen and the battery lasts less time. But these effects are short-lived – in the spring, the battery in snowy Michigan or cold Maine will regain full functionality, while the heat can reduce the maximum mileage forever.
“You can train people, but you can’t tell them not to live in Phoenix,” Case says. “That’s a bit unfair.”
Electric cars are becoming more common, and meanwhile the temperatures are rising. Because of this, drivers around the world will need to familiarize themselves with the best ways to maintain battery life. In the US specifically, some of the highest rates of electric car penetration are in hot spots. California, Florida, Texas, Arizona and Georgia are home to 56 percent of battery-powered vehicles, according to the Department of Energy. Fortunately, care can neutralize much of the impact of heat changes.
“Wherever there’s shade in the hot Texas summer, I try to find it,” says Skyler Williams, an Austin entrepreneur who learned about battery chemistry and maintenance before buying a Rivian R1S last August. “It doesn’t matter if I’m in the store for 10 minutes or 2 hours. Better to be safe than sorry.”
Williams follows other helpful tips: he only uses fast-charging stations when necessary, always leaves his car plugged in if it’s in his garage, rarely leaves the battery below 80 percent, and uses Rivian’s app to open his car windows if he is away from his truck on a hot day. After almost a year, his car has not lost any mileage, which is a good guarantee of resale value.
Battery life is quickly becoming the next critical metric in the EV market, driving the drive to quantify it at a granular level. Stephanie Valdez Streeti, director of strategic planning at Cox Automotive Inc., says four out of five EV buyers already consider battery life when making a purchase, which is one of the reasons her team developed its own metric to measure it.
“We’re still in intensive R&D mode, but that’s the vision,” she says. “Being able to buy a used EV is very important, and having a clear view of the battery’s condition will be key.”
Meanwhile, Recurrent is one step ahead. Three times a day, the company collects battery data from more than 17,000 electric vehicles registered in its service. Using this data, Recurrent can quickly rate any specific EV by viewing its mileage, state of charge and odometer. If the system can catch a car while charging, that will be even better.
An electric car that has experienced several summers in Texas, for example, will score worse than the same model with the same mileage in a temperate climate. Conversely, if a driver in Texas takes the right measures for his electric car, he will get a better Recurrent rating than the same car in a more temperate climate that is regularly driven until the battery is completely drained and then charged to 100% – a practice that increases the wear and tear on the lithium-ion battery.
“Manufacturers compete on three fronts: overall mileage, speed and cost of charging,” says Case. “They will also be responsible for a fourth direction – how long the first three will last.”
California regulators are already considering a proposal that would require a battery health measure for every electric car sold. To date, some of Recurrent’s best customers are dealerships in hot areas, where the difference between actual mileage and the “certified” mileage determined by the US Environmental Protection Agency can be huge.
“The EPA’s mileage certificates have been wrong since day one because they don’t account for temperature changes,” says Scott. “It’s a huge change that everyone needs to see.”
2023-07-12 14:41:00
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