Battery degradation isn’t likely to brick your EV, data confirms

Used EV buyers need not worry too much about the range of battery degradation down, according to a new study from Recurrent, which sells battery health reports for used EVs.

“Used EV buyers worry that car batteries will wear out as quickly as cellphone batteries, and won’t be able to charge them for years,” said Liz Najman, principal investigator at Recurrent, in a statement. “That’s not a pretty comparison because EV packages are complex technologies with battery management systems that carefully regulate things like charging and temperature.

Battery packs can deliver 50% to 70% of the EV value, but it’s a fairly long-lasting asset, according to Recurrent. The company’s study of 15,000 EVs found that only 1.5% required battery pack replacement due to degradation. It does not include packages replaced for recall.

2011 Nissan Leaf electric car after battery pack replacement [by owner Tim Jacobsen, Concord, CA]

Najman added that Recurrent’s research showed “that the battery lasts better than expected and replacement is not an automatic shock charge to the owner at 101,000 miles.”

And Recurrent emphasizes that battery degradation is not linear. While sharp drops in battery capacity do occur, they tend to slow down over longer periods, according to the study. So higher mileage EVs may experience slower battery degradation rates than newer cars.

Even when the battery pack needs to be replaced, most are done under warranty. The Tesla Model 3 Standard Range battery pack warranty guarantees 70% of original capacity for eight years or 100,000 miles. Tesla increased that to 120,000 miles for the rest of the Model 3 and Model Y variants, and 150,000 miles for the Model S and Model X. BMW and Volkswagen also guarantee 70% capacity for eight years or 100,000 miles.

EV owners can also help extend battery health by fast-charging only when needed, and trying to avoid pulling the battery too far between charges, notes Recurrent. Excess heat can also accelerate battery degradation, the company says, but liquid cooling for battery packs and better chemistry have allayed some concerns over accelerated degradation.

2014 Chevrolet Volt

For the Nissan Leaf, one of the longest running EV nameplates, the relatively long battery life has pushed recovery and recycling even further. California is trying to lock down that kind of longevity, proposing limits on battery degradation as part of its latest Advanced Clean Cars II (ACC II) rules for vehicle emissions and more.

While this study shows EV batteries can be quite powerful, the massive recalls for the Chevrolet Bolt EV and Hyundai Kona Electric due to battery defects, not degradation, still lead to many package changes. Even if these replacements come at no cost to owners, such a recall is unlikely to promote greater confidence in EVs.