A 2023 Hummer EV in Seattle, Washington.
(AdobeStock_593641307)

Martin Wahl

A two-year study at Stanford University showed that electric vehicle (EV) batteries last much longer than previously expected by using test protocols that simulate real-world EV battery usage. Traditional lab testing of EV batteries is a “constant-current” type, reflecting industrial and public transit type use: long periods of heavy use followed with short rest periods and intensive recharging. The new tests consider the typical intermittent charge and discharge cycles that happen when driving with regenerative braking and recharging with longer resting periods.

According to an Institute of Electrical and Electronics Engineers (IEEE) article¹:

The rhythms of real-world driving enable EV batteries to live far beyond the predictions of laboratory tests, according to a new study from Stanford University. The report, published in December in Nature Energy, suggests that EV batteries could last 38 percent longer than previous lab-based estimates. That means drivers could get as much as 314,000 kilometers (195,000 miles) more out of their EVs than academic researchers believed.

Because Americans drive an average 15,000 miles per year, that translates to an extra 13 years of battery life!

The researchers tested three new protocols over a two-year period, that incorporated short discharge cycles and lower-level charging to mimic regenerative braking, and measured wear on the batteries with resistance testing. All three protocols resulted in less wear on the batteries than the traditional test. Experts were surprised, because the conventional wisdom is that frequent charge and discharge cycles would lower battery life. They tested 92 batteries with the traditional constant current protocol as well as the three new methods, finding that those tests that more closely mimicked actual usage extended battery life further.

Nissan Leaf cutaway showing part of the battery in 2009. (TennenGas – Own work, CC BY-SA 3.0)

These results help explain the anecdotal evidence of long-term EV and hybrid owners that batteries were lasting 300,000 miles or more. A 2016 Tesla Model S 90D used as an airport taxi in the UK has logged more than 400,000 miles on its original battery and motors.

The researchers did not provide a hypothesis or speculation concerning the mechanism that increased battery life. The results suggest, however, that EV manufacturers should consider adjusting battery management software to adopt intermittent charging and resting.

The results contrast with real-world measures of gasoline powered vehicle miles-per-gallon show lower results when compared to EPA test results.

¹ From IEEE Spectrum, “EV Batteries Last Way Longer Than Expected” by Laura Hautala, January 29, 2025