A new study suggests that the average electric car’s battery could last as much as 40% longer than today’s tests predict.
How could the automotive industry have gotten something so fundamental so wrong? Because current tests don’t resemble the way drivers actually treat their cars, researchers say.
Related: EV Battery Health — The Essential Guide
Most Drivers Trickle Charge Out, Keep It Fairly High
Researchers from the SLAC-Stanford Battery Center explain, “Almost always, battery scientists and engineers have tested the cycle lives of new battery designs in laboratories using a constant rate of discharge followed by recharging.” This pattern — draining batteries close to zero, recharging them to 100% or near it, and discharging them fully again — is not how drivers treat their cars.
Most plug their cars in overnight and use them during the day for short runs that come nowhere close to full discharge. “The batteries of electric vehicles [EVs] subject to the normal use of real-world drivers — like heavy traffic, long highway trips, short city trips, and mostly being parked — could last about a third longer” than the usual testing method predicts, the authors write.
Related: How Long Do Electric Cars Last?
Battery Replacement Concerns Hold Some Shoppers Back
The numbers matter because “While battery prices have plummeted about 90% over the past 15 years, batteries still account for almost a third of the price of a new EV.” Some used car shoppers avoid EVs, even with their built-in $4,000 price discount, out of worries they’ll need to replace an expensive battery.
Related: Study: EV Battery Replacements Rare
“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,” says Simona Onori, senior author and an associate professor of energy science and engineering in the Stanford Doerr School of Sustainability.
The study appears in the December edition of the journal Nature.
