A comprehensive new study of over 8,000 electric vehicles (EVs) in the UK demonstrates that battery health remains remarkably strong even after years of use and high mileage. The findings, detailed in the Generational 2025 Battery Performance Index Industry Benchmark Report, challenge previous concerns about rapid battery degradation in EVs.
Battery Health Remains High Across Vehicle Age and Mileage
The study encompassed 36 different EV and plug-in hybrid (PHEV) makes, ranging in age from brand new to 12 years old, with some vehicles exceeding 160,000 miles (257,495km). The average battery health across all vehicles surveyed held at 95.15% of original capacity – a metric known as State of Health (SoH).
This means that even after significant use, batteries are holding up far better than many predicted. EVs aged between eight and nine years still retained an average of 85% of their original capacity, indicating that age alone doesn’t dramatically deplete performance.
High Mileage Doesn’t Equal Rapid Degradation
Surprisingly, the data suggests that high mileage doesn’t necessarily translate to faster battery decline. Vehicles with over 100,000 miles (160,000km) maintained between 88% and 95% battery health, often outperforming older EVs with lower mileage.
This raises a key point: battery condition is more important than odometer readings when evaluating a used EV. A well-maintained, three-year-old ex-fleet vehicle with high mileage could be a better investment than an older EV with limited use.
Warranty Coverage and Resale Value Implications
The study also highlights that manufacturer battery warranties are generally sufficient, with batteries often outlasting their specified coverage. This suggests that the risk of premature battery failure is lower than previously assumed.
In Australia, where warranties typically last around eight to ten years, these findings are particularly relevant. Battery condition will continue to be a major factor in the long-term resale value of EVs, potentially more so than mileage alone.
The research confirms that battery degradation is no longer the systemic risk it once was, meaning buyers can approach the used EV market with greater confidence.
The data underscores the increasing reliability of EV batteries and their potential to deliver long-term value, pushing the industry further toward mainstream adoption.
