A large new study suggests that electric car batteries last longer than many drivers fear. Aviloo, an Austrian company that tests battery health, published the study on 2 September 2026. The Financial Times reported it on the same day.

What the study found

Aviloo analysed more than 500,000 battery tests on used electric cars. The tests took place between 2022 and 2026, on 20 popular models. The Financial Times reports that the study did not include Chinese models, because there was not enough data.

The study measures state of health. This is the percentage of the battery's original usable capacity that remains. Across the 20 models, the median state of health was:

  • 91% to 97% after 50,000 km

  • 88% to 95% after 100,000 km

  • 87% to 94% after 150,000 km

Cars of the same model can differ

Battery health varied by up to 13.5 percentage points between cars of the same model. The Tesla Model Y varied by up to 11 points. The Volkswagen ID.4 varied by 11 to 12 points, and the Hyundai Ioniq 5 by more than 12 points.

Climate, battery size and driver habits all had an effect. Batteries in hotter climates degraded faster. Smaller batteries need more charge cycles to cover the same distance, and they tended to degrade faster too.

Marcus Berger, chief executive of Aviloo, told the Financial Times that drivers should not leave a parked car at a high state of charge. In his view, the ideal level is between 30% and 70%.

Warranties and certificates

Battery warranties typically cover eight years or 100,000 miles (160,000 km). Under these warranties, the maker must replace a battery whose capacity falls below 70%.

The Financial Times also reports that three large UK electric vehicle organisations asked the government for mandatory battery health certificates for used cars.

What this means for fleets

Fleet vehicles cover high mileage, so battery health affects their whole-life cost and their resale value. An independent battery test gives a measured figure, not a dashboard reading.

Onward develops ultra-rapid charging hubs for commercial fleets as well as for drivers. See how an Onward hub serves fleets.

Sources

  • Aviloo, [AVILOO launches world's largest independent EV battery study](https://aviloo.com/files/Aviloo/Presse/Berichte/AVILOO%20Launches%20Worlds%20Largest%20Independent%20EV%20Battery%20Study.pdf) (PDF), 2 September 2026.

  • Financial Times, EV batteries last longer than drivers feared, Kana Inagaki and Clara Murray, 2 September 2026. A subscription may be necessary.