Electric vehicle batteries are lasting far longer than many drivers and industry insiders had feared.

According to what is being described as the UK’s largest study of used battery-electric vehicles, most batteries will outlast the vehicle they power.

This latest research undermines a key aspect of the original and ongoing campaigns that have been negatively pitted against the switch to EVs.

Plugging in

New data from battery diagnostics specialist Generational, published in its 2025 Battery Performance Index, analysed more than 8,000 electric cars and light commercial vehicles.

Drawing on assessments across 36 manufacturers, the study covered vehicles aged between zero and 12 years, with mileages ranging from delivery mileage to more than 160,000 miles.

The headline finding is striking: the average battery state of health (SoH) across the entire test fleet was 95.15% of original capacity.

Even vehicles aged eight to nine years retained a median 85% battery capacity compared to new, while four- to five-year-old EVs recorded a median SoH of 93.53%.

Miles and miles

Manufacturers typically warranty EV batteries to maintain at least 70% capacity for eight years or 100,000 miles, whichever comes first.

Generational’s data indicates that the vast majority of vehicles comfortably exceed this threshold.

While a small minority fall outside warranty parameters, likely resulting in claims, the overall picture is far more robust than many had assumed.

High-mileage vehicles also performed strongly.

EVs with more than 100,000 miles frequently returned SoHs between 88% and 95%, challenging the perception that heavy use rapidly erodes battery performance.

The Index also reveals how battery health varies by age.

Among four and five-year-old vehicles, the median was 93.53%.

In the 8 to 12-year-old cohort, the median was 85.04%.

However, while average performance remains strong, variance increases over time.

In other words, well-maintained vehicles can significantly outperform poorly maintained ones as they age.

Changing views

Generational says the findings confirm that battery degradation is “not the systemic risk once assumed”.

In many cases, younger high-mileage vehicles outperform older low-mileage equivalents, undermining appraisal models inherited from the internal combustion engine era.

A three-year-old fleet car with 90,000 miles may offer stronger battery health than a six-year-old car with 30,000 miles, depending on charging behaviour, thermal management and duty cycle.

Of course, wear and tear on other parts of the vehicle must be taken into consideration if you are looking to buy a used EV, but battery health is not necessarily the concern it was once believed to be.

Oliver Phillpott, CEO of Generational, said, “EV batteries are performing far better than many consumers and industry stakeholders have been led to believe”.

He adds that “even older vehicles [are] comfortably exceeding warranty thresholds”, but that transparency is now the critical issue, and that visible battery health information needs to be standard, rather like Smartphones .

“By establishing clear benchmarks for what is typical, above and below average, we are giving the market the reference points it needs to price risk accurately, strengthen residual values and accelerate adoption.”

Boosting conversion

Industry bodies agree that trust is central to the used EV market’s development.

Philip Nothard, chair of the Vehicle Remarketing Association, said buyers place huge emphasis on battery health and need reassurance that the most expensive component will not deliver unpleasant surprises.

The Generational findings mirror separate research from telematics specialist Geotab, which analysed data from more than 22,700 EVs and found an average annual degradation rate of 2.3%.

For consumers and fleets alike, the message is clear: most EV batteries are likely to outlast the vehicles themselves.

But as the market matures, verified battery health data is becoming as fundamental as service history or mileage checks – and increasingly essential to unlocking confidence and value in the used electric car sector.