Used EVs going strong with average 95% average battery health
The average used EV in the UK still has more than 95% of its original battery capacity, according to a new large-scale study by industry expert Generational.
Launched today, Generational’s Battery Performance Index is the UK’s largest-ever analysis of EV battery condition, revealing the average battery State of Health (SoH) of more than 8,000 passenger cars and light commercial vehicles.
SoH shows a battery’s current available capacity relative to its maximum capacity, and is indicated as a percentage from 0% to 100%. SoH is key to measuring an EV battery’s longevity and durability.
The Generational Battery Performance Index covered vehicles from 36 manufacturers, using vehicles built between 2013 and 2025. Mileages ranged from 0 to more than 160,000 miles.
The data revealed that the overall average SoH was 95.15%, with vehicles between eight and nine years old retaining a median of 85% SoH. This is important because with most manufacturer battery warranties running for seven or eight years, the findings showed that the usual warranty threshold of 70% SoH was rarely approached.
Numbers were positive for high-mileage EVs. Those with over 100,000 miles on their clock frequently returned an SoH of 88-95%, while those in the four/five-year-old bracket displayed an SoH of 93.53%.
The Generational Battery Performance Index was also broken down into percentile benchmarking by vehicle age.
The bottom-performing percentile in the four-five-year age group displayed a 91.64% average SoH; those in the middle displayed 93.53%, while those at the top displayed 96.49%.
For older models in the eight-12 year-old bracket those in the bottom percentile retained an 82% SoH despite their advancing years, mid-percentile vehicles retained 85.04%, while top-rankers sat at 90%.
Overall, the Battery Performance Index revealed that battery degradation amongst used EVs is no longer the risk it was once perceived to be. Instead, the biggest concerns when buying a used EV are related to the vehicle’s condition and how it has been used.
Nonetheless, battery health is becoming essential on the used EV market, as worst-case assumptions can negatively affect pricing and consumer decision-making. Transparency here will be key to driving the second-hand EV market.
Mileage alone is becoming an increasingly unreliable indicator of battery condition. As the Battery Performance Index showed, younger high-mileage vehicles often outperform older, low-mileage cars in terms of battery health.
For example, a three-year-old fleet vehicle with 90,000 miles on the clock could be a stronger battery proposition than a six-year-old vehicle with 30,000 miles, depending on usage and charging behaviour.
The findings dispelled the myth inherited from petrol and diesel cars that high milers are less efficient.
As the data from the first-ever Index are made public, Generational CEO, Oliver Philpott, 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.”
