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new research suggests these batteries, once thought to have short-lived, inherently expendable shelf-lives, may actually last significantly longer than expected. In some cases, properly cared for EVs may even outlive their fossil fuel counterparts. That’s potentially good news: longer-lasting EVs might buy manufacturers much-need time to fabricate components needed to meet increasing global demands.
The new findings, published today in the journal Nature Energy by researchers from the SLAC-Stanford Battery Center, suggest EV batteries may actually last about a third longer than previous forecasts. That means drivers could potentially keep driving their modern EV without replacing the battery for several additional years. The researchers note the shocking disparity in battery life estimates stems from fundamentally unrealistic testing environments that became an industry standard. When the researchers tested batteries for two years in ways they say are more closely aligned with how drivers actually use EVs day-to-day, the battery life expectancy improved significantly.
“We’ve not been testing EV batteries the right way,” Stanford associate professor and paper senior author Simona Onori said in a statement. “To our surprise, real driving with frequent acceleration, braking that charges the batteries a bit, stopping to pop into a store, and letting the batteries rest for hours at a time, helps batteries last longer than we had thought based on industry standard lab tests.”
SLAC-Stanford Battery Center states on its website that its ultimate goal is to “accelerate the deployment of battery and energy storage technologies at scale,” in an effort to address climate change. The research paper was primarily funded by the National Science Foundation Graduate Research Fellowship Program and the Stanford Chevron Fellowship in Energy.
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More ‘realistic’ driving led to less battery degradation
Researchers tested 92 commercial lithium ion EV batteries over two years across four different types of driving profiles. The industry standard approach uses a “constant rate of [battery] discharge” followed immediately by a recharge. In the real world, this would look like someone driving their vehicle until the battery is almost fully diminished and then plugging it in to charge completely. This process of constant battery expenditure and recharging resembles how most people use a smartphone.
Stanford school of engineering PhD student and paper coauthor Alexis Geslin told Popular Science these “constant current rates” were adopted as the testing default because it generally requires simpler hardware and is easier to implement for the lab user.
But that’s not how many drivers actually use their vehicles. EV owners, the researchers note, who drive their vehicle in short bursts to and from work or around town, may go several days or even a week without recharging. The researchers attempted to represent that more realistic, periodic driving method in one of the driving profiles. In the end, the more realistic profile resulted in an increased battery lifetime by up to 38%.
“This work illustrates the importance of testing batteries under realistic conditions of use and challenges the broadly adopted convention of constant current discharge in the laboratory,” the researchers wrote in the paper.
The findings similarly seem to contradict commonly held assumptions about what types of driving quickly degrades batteries. Though many drivers believe rapidly accelerating and braking degrades EV batteries faster than steady driving, the researchers found a correlation in their data suggesting sharp, short accelerations may actually lead to slower battery degradation. Pressing down hard on pedals with a lead foot didn’t seem to speed up battery aging. It may have actually had the opposite effect.
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Source: Surprise: EV batteries might have a longer shelf live than once thought | Popular Science
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