Generational has published its 2025 Battery Performance Index – the largest analysis of EV battery condition undertaken in the UK. It reveals the average battery state of health (SoH) across more than 8,000 tested passenger cars and light commercial vehicles stands at a robust 95.15% of capacity compared to new.
The Battery Performance Index establishes clear benchmarks for what can be considered typical, above average and below average battery degradation in UK vehicles moving through 2026. It also provides a new reference point for consumers and the industry across retailers, fleet operators, insurers and financiers.
Drawing on battery assessments conducted across 36 manufacturers, vehicle ages from 0-12 years and mileages from 0-160,000+ miles, Generational’s data shows:
- Overall average SoH is 95.15%.
- 8-9 year old vehicles retain a median 85% capacity.
- High mileage EVs (100,000+ miles) frequently return 88-95% SoH.
- Even within the 4-5 year old cohort, median SoH remains strong at 93.53%.
- OEM warranty thresholds (typically 70% SoH over eight years/100,000 miles) are rarely approached.
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. It 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. For example, 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.
Oliver Phillpott, CEO of Generational, said:
“The 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 SoH 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 – 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.”
Contributors
Rob Shepherd (author)
Rob is Consulting Editor for InstallerELECTRIC. He is a well-respected journalist with a strong history in the electrical sector.
