When Kerry Dunstan and his partner decided to buy a second-hand electric car this summer, their first question was not about mileage or model year—but the battery’s health. The couple found a 2021 Nissan Leaf with 29,000 miles and a reported battery state of health (SOH) of 93%. For £12,500, they purchased the car, confident in its range and reliability.
As electric vehicles (EVs) increasingly dominate the roads, assessing battery performance has become central to the used-car buying process. Traditionally, age and mileage were the key indicators of a vehicle’s condition, but for EVs, the battery’s history—how often it was fast-charged, how it was stored, and how it has aged—matters far more. Improper charging habits, such as consistently fast-charging to 100%, can shorten a battery’s lifespan, making buyers cautious.
This uncertainty has given rise to a new industry of battery analytics companies offering independent testing. Austria-based Aviloo, for example, provides diagnostic tests that determine a battery’s true health. “We can independently determine the state of health of a battery,” said Aviloo’s chief product officer, Patrick Schabus. The firm offers two services: a detailed “premium test,” which monitors battery performance over several days, and a quicker “flash test,” which provides results in under two minutes.
Aviloo’s chief executive, Marcus Berger, said their findings often differ from the SOH percentages shown on cars’ built-in systems. He also challenged the notion that batteries below 80% SOH are near the end of their life. “An EV with a state of health below 80% can still be a great car—it just needs to be priced appropriately,” he said.
In the UK, Cleevely Electric Vehicles in Cheltenham relies on independent battery analytics to reassure buyers. “Most customers ask for this information,” said sales director David Smith. “Once they’ve seen the report, it aids the sale nine times out of ten.”
Battery technology itself has also evolved. Max Reid of research firm CRU noted that older batteries typically lasted 500–1,000 charge cycles, while newer models can last up to 10,000. And even when an EV battery is no longer roadworthy, it can be repurposed for energy storage. Dorset-based Second Life EV Batteries repurposes used packs for industrial energy storage systems, giving them a “second life” beyond the car.
Experts believe that clearer standards for reporting and testing battery health would boost confidence in the used EV market. Until then, as Dunstan’s experience shows, understanding a car’s battery—rather than just its age—has become the key to making an informed electric purchase.
