A massive new EV study just dispelled the biggest myth about electric car batteries

• A new report is the largest-ever analysis of EV battery condition in the UK
• Results suggest that older vehicles retained a median 85% battery capacity
• Even very high-mileage vehicles rarely trouble their manufacturer warranty

The latest results from Generational’s 2025 Battery Performance Index reveal that EV batteries are more robust and reliable than predicted, with most packs likely to exceed the lifespan of the vehicle itself.

Generational, which is a UK-based innovator in electric vehicle battery condition diagnostics, claims the report is the largest analysis of EV battery condition undertaken in the UK, with more than 8,000 passenger cars and light commercial vehicles analyzed in the study.

The results show that the average battery State of Health (SoH) across all of those used vehicles involved stands at a robust 95.15% of capacity compared to new.

The battery assessments were conducted across some 36 manufacturers, including vehicle ages from 0 to 12 years and mileages from zero to over 160,000 miles, with results proving that even eight- to nine-year-old vehicles still retained a median 85% capacity.

High mileage EVs, or those with more than 100,000 miles on the clock, frequently returned an 88-95% State of Health result, according to the report’s authors.

The evidence is designed to boost consumer confidence where second-hand and older EVs are concerned – a market that has been struggling with residual values partly due to this reason.

Many used EV buyers assume they will inherit a vehicle that can only manage a small fraction of its original claimed electric range.

But in stark contrast, Generational’s findings show that original manufacturer warranty thresholds, which are typically triggered when a battery State of Health drops to 70% over eight years or 100,000 miles, are rarely approached.

Boosting consumer confidence

Results showed that even the bottom-performing 25th percentile of the group that contained eight- to 12-year-old vehicles still retained an 82% average State of Health.

Naturally, the company that carried out the research is keen to make clear its message that battery degradation is not the systemic risk once assumed, but rather the way the vehicle is used, stored and charged all play a major role in battery health.

“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,” Oliver Phillpott, CEO of Generational said.

Phillpott believes that by establishing clear benchmarks for what is a typical, above and below average State of Health will give the used EV market clearer reference points to price accurately, strengthen residual values and accelerate EV adoption in general.

Where the condition of an internal combustion engine can generally be predicted in line with its mileage, seeing as general wear and tear is relatively linear, the same can’t be said of EVs, with recent studies suggesting that numerous factors play a role in how well a battery pack holds up.

Generational says this is why it is important to have verified battery tests for all used EVs. Without transparent condition data, worst-case assumptions can dominate pricing and decision-making, they claim.

But overall, the results from the UK’s largest battery study prove that, once again, real-world battery degradation is much slower than many assume.

Granted, there will be naysayers who give examples of ICE vehicles with hundreds of thousands of miles on the clock, but most of those engines will have had almost every part replaced anyway.

The point here is that EVs can happily run for ten years without needing to have their battery pack swapped, which should give potential buyers the confidence that their vehicles will be worth something when it comes to replacing them.

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