Used EV batteries are performing “materially better” than widespread assumptions, according to a major new real-world study. Generational, a UK-based innovator in EV battery condition diagnostics, analysed more
Used EV batteries are performing “materially better” than widespread assumptions, according to a major new real-world study.
Generational, a UK-based innovator in EV battery condition diagnostics, analysed more than 8,000 passenger cars and LCVs and found that average battery health stands at a robust 95.15% compared to new.
The 2025 Battery Performance Index, said to be the largest analysis of electric vehicle battery condition undertaken in the UK, also gives key insights on battery degradation for older EVs and the impact of mileage on state of health.
Launched to provide clear benchmarks for what can be considered typical, above-average and below-average battery degradation in UK vehicles, the index is aimed at drivers as well as the wider EV industry including dealers, fleet operators, insurers and financiers.
It draws on battery assessments conducted across 36 manufacturers, vehicle ages from 0-12 years and mileages from zero to over 160,000 miles.
Key findings include:
The index also breaks down into percentile benchmarking by vehicle age.
Among four- to five-year-old vehicles, the 25th (bottom-performing) percentile sits at 91.64% state of health, the median at 93.53%, and the 75th (top-performing) percentile at 96.49%.
In the eight- to 12-year-old cohort, the 25th percentile is 82%, median 85.04% and 75th percentile 90%.
Generational said the data reveals that older EVs remain robust. In the vast majority of cases, EV batteries are likely to exceed the lifespan of the vehicle itself. Even vehicles approaching the end of typical OEM battery warranty periods are performing comfortably above minimum thresholds.
But there are some caveats. The study shows that variance increases materially over time, creating a growing performance gap between well-maintained vehicles and underperformers.
The index also demonstrates that mileage alone is an “increasingly unreliable” indicator of battery condition.
In many cases, younger high-mileage vehicles outperform older low-mileage equivalents, challenging traditional appraisal models inherited from the internal combustion era.
A three-year-old fleet vehicle with 90,000 miles may represent a stronger battery proposition than a six-year-old vehicle with 30,000 miles, depending on usage and charging behaviour.
Generational said the data confirms that battery degradation is not the “systemic risk” once assumed, with uncertainty around condition now the principal determinant of used EV confidence, residual values, performance and risk.
Oliver Phillpott, chief executive, commented: “The Generational Battery Performance Index definitively shows that EV batteries are performing far better than many consumers and industry stakeholders have been led to believe. With an average state of health of over 95%, and even older vehicles comfortably exceeding warranty thresholds, the underlying fundamentals are extremely strong.
“Transparency in battery condition is the main challenge facing the market today, and essential infrastructure for a healthy used EV sector; as vehicles age, the variance between the best and worst performers widens, and that dispersion defines risk.
“By establishing clear benchmarks for what is typical, above and below average as we look to drive further growth in 2026, we are giving the market the reference points it needs to price risk accurately, strengthen residual values and accelerate adoption.”
The firm added that the increasing dispersion of performance over time underlines why verified battery testing is becoming essential. Battery transparency is fast-evolving to be as fundamental as service history or mileage verification, and the index identifies strategically significant implications for players across the automotive ecosystem.
For fleets, battery transparency supports improved duty-cycle optimisation, holding-period decisions and stronger remarketing outcomes – improving total cost of ownership calculations.
Philip Nothard, chair of the Vehicle Remarketing Association, said: “Potential buyers of used electric cars and vans understandably place a huge emphasis on battery health. They need to trust that this fundamental and expensive vehicle component will meet their needs without any unpleasant surprises.
“Transparency will prove crucial in building future consumer confidence and dispelling the many misconceptions that have gained currency around EV batteries.”
To access Generational’s 2025 Battery Performance Index, please click here.
