A study of electric vehicles (EVs) has demonstrated stronger-than-expected performance for older batteries, even when significant mileage has been clocked up.
In the largest study of its kind so far, the Generational 2025 Battery Performance Index Industry Benchmark Reportexamined more than 8000 electric passenger cars and light commercial vehicles in the UK.
It included 36 different vehicle makes and both plug-in hybrid (PHEV) and battery-electric vehicles (EVs), with an age range of zero (brand-new) to 12 years and mileage of up to 160,000 miles (257,495km).
While it didn’t specify battery types across the vehicles surveyed, it found that average battery health remained at 95.15 per cent of the original capacity when new – known as the State of Health (SoH).
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Older EVs aged between eight and nine years still maintained 85 per cent of their original capacity, according to the data, suggesting age does not significantly deplete battery health.
It also showed high-mileage vehicles – those which had travelled more than 100,000 miles (160,000km) – maintained between 88 per cent and 95 per cent battery health.
The study found that minimising mileage didn’t bring substantially longer battery life, with the battery health of younger, high-mileage vehicles typically outperforming that of older, low-mileage vehicles.
It concluded that a well-maintained three-year-old ex-fleet EV with 120,000km on its odometer may be a better purchase than a six-year-old vehicle with only 50,000km on the clock.
It also showed that most manufacturers’ battery warranties are more than long enough and that batteries typically outperform warranty parameters – often exceeding the lifespan of the vehicle – resulting in few claims from customers.
In Australia, battery warranties commonly extend to around eight years, with some brands offering up to 10 years.
The report said battery degradation is no longer the ‘systemic risk’ it was previously seen as, with battery condition still being the major factor in the long-term resale value of used EVs – as opposed to their odometer readings.
| Age (years) | 25th percentile | 50th percentile | 75th percentile |
|---|---|---|---|
| 0-1 | 97.91 | 100.00 | 100.00 |
| 1-2 | 97.23 | 100.00 | 100.00 |
| 2-3 | 95.00 | 96.94 | 99.89 |
| 3-4 | 92.98 | 95.17 | 98.19 |
| 4-5 | 91.64 | 96.49 | 96.49 |
| 5-6 | 89.01 | 92.26 | 96.00 |
| 6-7 | 88.13 | 90.75 | 93.50 |
| 7-8 | 87.96 | 90.00 | 93.85 |
| 8-12 | 82.00 | 85.04 | 90.00 |
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