A new large‑scale UK dataset suggests EV batteries are holding up far better than many skeptics expected.
London‑based EV battery diagnostics company Generational analyzed more than 8,000 battery tests across 36 automakers and found the average EV battery State of Health (SoH) is 95.15% of original capacity. The results cover passenger cars and light commercial vehicles ranging from brand‑new to 12 years old and with anywhere from zero to more than 160,000 miles on the odometer.
That’s a strong real‑world data point as debates about battery lifespan, resale value, and long‑term ownership costs continue to shape consumer confidence in used EVs.
What EV battery health data shows
Across the entire sample, battery health remained high even as vehicles aged:
- Average State of Health across all vehicles: 95.15%
- 4‑5‑year‑old EVs: median 93.53%
- 8‑9‑year‑old EVs: median 85%
- High‑mileage EVs (100,000+ miles): frequently 88–95% SoH
Even older vehicles rarely approached typical manufacturer warranty coverage, which is usually around 70% of the original capacity after eight years or 100,000 miles.
The dataset also shows a widening performance gap as vehicles age. Among 4‑ to 5‑year‑old EVs, the lowest‑performing quartile averaged 91.64% SoH, the median sat at 93.53%, and the top quartile reached 96.49%. In older 8‑ to 12‑year‑old vehicles, the bottom quartile averaged 82%, the median 85.04%, and the top quartile 90%.
That spread suggests battery condition depends heavily on factors like usage patterns and charging behavior, not just age.
Mileage isn’t the best predictor anymore
One of the clearest takeaways from the report is that mileage alone isn’t a reliable indicator of battery health. In some cases, a younger vehicle with very high mileage outperformed an older car that had been driven less.
In other words, a three‑year‑old fleet EV with 90,000 miles could have a healthier battery than a six‑year‑old car with only 30,000 miles, depending on how both were used and charged. That runs counter to how used vehicles have traditionally been evaluated in the gas‑car era.
Why battery transparency matters
Generational argues that uncertainty about battery condition – not actual degradation – is now the biggest factor affecting used‑EV pricing, risk assessments, and buyer confidence. Verified testing data could become as standard as service records or mileage verification in used‑car listings.
Philip Nothard, chair of the Vehicle Remarketing Association, said buyers of used EVs understandably focus on battery health because it’s the most expensive component in the vehicle. “Transparency will prove crucial in building future consumer confidence and dispelling the many misconceptions that have gained currency around EV batteries.”
What it means for the EV market
The findings carry implications across the industry. For automakers, real‑world durability data strengthens their case for talking more confidently about battery longevity and residual values. For insurers and warranty providers, verified battery condition could allow pricing and coverage to be based on actual performance rather than conservative assumptions tied only to age and mileage.
Fleet operators could use clearer battery visibility to refine vehicle rotation strategies and improve total cost of ownership calculations. And for policymakers, standardized battery health reporting could help ease concerns about replacement costs, which remain one of the biggest perceived barriers to EV adoption.
Electrek’s Take
Overall, the dataset suggests that most EV batteries will likely outlast the vehicles’ usable life. My colleague Jamie Dow has one of the first EVs you could buy, a 2008 Tesla Roadster, which is on its original, 18-year-old battery. The car has around 33,000 miles on it, and Jamie keeps it charged at the 40-60% range. He says his car battery has about 80% of its original capacity, despite having a three-year warranty on the original battery. It turns out that batteries are more durable than many feared, as today’s report confirms.
But it also highlights a growing divide between well‑maintained and poorly maintained batteries – a gap that becomes more pronounced as EVs age and enter the used market.
If battery health reporting becomes widespread – or even better, standard practice – it could remove much of the guesswork that still shadows secondhand EV pricing today.
Read more: ION ships first commercial solid-state battery cell samples
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