Today’s EV Batteries May Last Up to 40% Longer Than Expected, Study Finds

A new study has revealed that modern batteries in electric vehicles may last up to 40% longer than expected thanks to stop-and-go driving patterns that help recharge batteries on the go.

According to researchers, the common lab testing methods to determine battery life may not be the most accurate way to estimate how long EV batteries will last. In lab testing, batteries are often discharged at an ongoing rate, then recharged all at once. 

But as the researchers pointed out, EV drivers experience different discharge rates in long spans of driving or stop-and-go traffic. These more frequent cycles of discharging the battery and recharging during braking could help preserve battery life.

Researchers tested 92 commercial lithium-ion batteries for a 24-month period, using both the constant discharge method as well as real-driving scenarios. The batteries tested under real driving methods had a better life expectancy, with about 38% improvement, compared to those tested under common lab testing scenarios. The team published the findings in the journal Nature Energy.

“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,” Simona Onori, senior author of the study and an associate professor of energy science and engineering at Stanford University’s Doerr School of Sustainability, said in a statement.

According to the National Renewable Energy Laboratory, EV batteries are estimated to last for around 12 to 15 years in mild climates or around 8 to 12 years in extreme climates. But the real battery degradation of EVs is still difficult to determine, since many EVs that are currently on the road were bought within the last few years, Recurrent Auto reported, with many EV batteries lasting well beyond the common 8-year, 100,000 mile warranty.

Although Electrek reported that battery prices just fell by the biggest rate since 2017, with a 20% drop in battery prices for 2024, the prices can still be of concern to consumers considering the switch to an EV over a gas-fueled vehicle. As the study authors pointed out, EV batteries still make up about one-third of the cost of a new electric car. Further, according to NerdWallet, replacing an out-of-warranty electric car battery can cost between $5,000 to $20,000. 

But with an increased longevity for EV batteries, swapping to an EV could be a more economical choice for consumers when compared to paying for more frequent battery replacements, plus fuel, in gas-powered vehicles. As NerdWallet reported, traditional vehicle batteries cost around $60 to $300 each, with replacements necessary every 3 to 5 years, according to AAA.

As Electrek reported, electric batteries are predicted to fall even lower in the coming years, reaching around $69 per kWh by 2030.

The findings could also improve consumer confidence in secondhand EVs, considering a Green Finance Institute survey found that 62% of respondents who didn’t already own an EV said they wouldn’t buy a used electric car due to concerns over battery health.

Although the researchers noted that dynamic cycling can extend the lifespan of an EV battery compared to constant cycling, they explained that time-induced aging will still affect batteries. Proper battery charging practices and vehicle maintenance will still be important for users to consider when maximizing the lifespan of their EV batteries.

“We battery engineers have assumed that cycle aging is much more important than time-induced aging. That’s mostly true for commercial EVs like buses and delivery vans that are almost always either in use or being recharged,” said Alexis Geslin, a lead author of the study and a Ph.D. student in materials science and engineering as well as in computer science at Stanford University’s School of Engineering. “For consumers using their EVs to get to work, pick up their kids, go to the grocery store, but mostly not using them or even charging them, time becomes the predominant cause of aging over cycling.”