Electric vehicle buyers often worry about one major component: the battery. Replacing an EV battery can be expensive, making long-term battery health an important consideration when purchasing a new or used electric car.
However, a massive new analysis of more than 500,000 independent EV battery tests suggests that battery degradation may not be as severe as many people fear. The study examined 20 popular electric car models and found that several continued to retain more than 90% of their original battery capacity even after 150,000 km of driving.
Mercedes EQA Leads The Long-Term Battery Test
The study, conducted by Austrian battery diagnostics company AVILOO, analysed independent battery health tests collected between 2022 and 2026.
Among the 20 models examined, the Mercedes-Benz EQA recorded a median battery State of Health of 94% after 150,000 km.
The Hyundai IONIQ 5 followed closely at 93.8%, while the BMW i4 recorded 93.6%. The Hyundai Kona Electric and Volvo XC40 Recharge also retained more than 92% of their median battery capacity at the same mileage.
State of Health, or SoH, represents the percentage of a battery’s original usable capacity that remains.
Most EV Batteries Retain Around 90% Capacity
The findings are particularly interesting for people considering used electric cars.
At 150,000 km, several popular EVs still had median battery health above 90%. The Ford Mustang Mach-E and Polestar 2 were around 92.5%, while the Volkswagen ID.3 remained close to 92%.
Even models with lower results retained a substantial portion of their original capacity.
The Tesla Model Y recorded 90.3% battery health at 150,000 km, while the Model 3 recorded 88.9%.
Small-Battery EVs Show More Degradation
One of the clearest patterns in the research was that smaller battery packs tended to experience greater degradation.
The Nissan Leaf ZE1 recorded a median SoH of around 86.7% at 150,000 km. The Renault Zoe and MINI Cooper SE were also below 88%.
One possible reason is that smaller batteries need to go through more charging cycles to cover the same distance as larger battery packs.
The study therefore suggests that battery size can be an important factor when evaluating long-term EV battery performance.
Same EV Model Can Have Very Different Battery Health
Perhaps the most important finding is that two identical EVs with similar mileage can have significantly different battery conditions.
AVILOO found differences of up to 13.5 percentage points in State of Health between individual vehicles of the same model.
Factors such as climate, charging habits, battery chemistry, age and charging cycles can influence degradation.
This means an EV’s odometer reading alone may not tell the complete story about its battery.
Battery Health Matters When Buying A Used EV
For used EV buyers, the study highlights the importance of checking the actual condition of the battery rather than relying solely on the vehicle’s age or mileage.
A car that has travelled 120,000 km could potentially have healthier battery capacity than another vehicle of the same model with considerably lower mileage.
Independent battery testing can therefore provide useful information before purchasing a used EV.
EV Battery Fears May Need A Rethink
The results provide a relatively reassuring picture of EV battery durability. Several models retained more than 90% of their original usable capacity after 150,000 km.
However, the study also shows that battery degradation varies considerably between models and individual vehicles.
For EV owners, driving habits, charging practices, climate and battery chemistry can all influence long-term performance.
For buyers, the key lesson is simple: don’t judge an EV battery purely by its mileage. Checking the actual battery health could be far more useful when determining how much usable life remains.
Summary
A major analysis of more than 500,000 EV battery tests found that several electric cars retain more than 90% of their original battery capacity after 150,000 km. Mercedes EQA, Hyundai IONIQ 5 and BMW i4 recorded particularly strong results, while smaller-battery models showed greater degradation. The study also found significant differences between individual vehicles, making independent battery testing important for used EV buyers.
