Generational, the UK-based electric vehicle battery condition diagnostics company, has revealed in its 2025 Battery Performance Index that the average battery State of Health (SoH) stands at 95.15% of capacity compared to new.
The Index looked at more than 8,000 tested passenger cars and light commercial vehicles (LCV) to establish benchmarks for what can be considered typical, above-average, and below-average battery degradation in UK vehicles through 2026.
Drawing on battery assessments conducted across 36 manufacturers, vehicle ages from zero to 12 years and mileages from zero to over 160,000 miles.
Generational’s data showed that eight to nine-year-old vehicles retain a median 85% capacity, while high-mileage EVs (100,000+ miles) frequently return 88-95% SoH.
Within the four to five-year cohort, median SoH is at 93.53%.
The data also showed that OEM warranty thresholds – typically 70% SoH over 8 years/100,000 miles – are rarely approached.
Among four to five-year-old vehicles, the 25th (bottom-performing) percentile sits at 91.64% SoH, the median at 93.53%, and the 75th (top-performing) percentile sits at 96.49%.
In the eight to 12-year-old cohort, the 25th percentile is 82%, the median 85.04%, and the 75th percentile 90%.
Generational said that this widening spread with age shines a spotlight on how, while averages remain strong, variance increases materially over time, creating a growing performance gap between well-maintained vehicles and underperformers.
Oliver Phillpott, CEO of Generational, said: “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.”
Philip Nothard, chair of the Vehicle Remarketing Association, added: “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.”
