A new study on the health of electric vehicle (EV) batteries shows that modern EV batteries perform strongly throughout their lifespan, even as fast charging becomes increasingly common. For this study, actual measured data on the health of batteries from over 22,700 electric vehicles from 21 brands and models were analyzed, based on multiple years of data. According to the new calculations, the average annual degradation of EV batteries is 2.3 percent, compared to 1.8 percent in the study conducted by Geotab in 2024.
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Fast charging has the greatest impact
The analysis shows that charging power today has the greatest impact on the health of EV batteries. Vehicles that frequently opted for fast charging above 100 kW showed a faster decline, averaging up to three percent per year. In vehicles that primarily charge with AC or lower power, the health of the battery declines by about one and a half percent per year.
Other factors, such as climate, had a more limited effect. Vehicles used in warmer regions experienced degradation about 0.4 percent per year faster than vehicles in temperate climates.
The data also questions the necessity of strict daily charging limits. Vehicles that regularly opted for a larger charging range showed no significantly higher degradation unless they were truly charged almost fully or nearly empty for long periods and very frequently.
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About the degradation of EV batteries
Battery degradation is a natural process that causes a battery to store less energy over time. The condition of a battery is measured as the state of health (SOH). Batteries start their lifespan with an SOH of 100 percent and gradually deteriorate. A 60 kWh battery operating at an SOH of 80 percent, for example, behaves effectively like a 48 kWh battery.
Data from Geotab shows that, although the degradation rate varies by model, charging behavior, and usage patterns, most modern EV batteries remain well within the typical lifespan of the vehicle.
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