When Kerry Dunstan and his partner went car shopping this summer, one question guided them: “How’s the battery?” They found a 2021 Nissan Leaf with 29,000 miles, and the dealer said its state of health (SOH) was still 93%. That was enough to convince them. For £12,500, they bought a practical electric car with a large boot and decent space.
Dunstan, a cabinetmaker who also owns a sleeker electric Volvo SUV, admits the Leaf doesn’t excite him. “I like sporty cars – and this one’s a bit dull,” he says. Still, he’s satisfied. “It’s done exactly what I expected,” he adds.
Why battery health now matters more than mileage
In the past, used car buyers focused on age and mileage. Today, battery health defines the deal. People want to know how the previous owner charged and used the car. Frequent fast charging to 100% can shorten the battery’s life.
This “battery black box” problem makes some hesitant about buying a second-hand EV. But new analytics companies claim they can assess a battery’s true condition with precision. Experts even say many electric cars last longer than expected.
Take Dunstan’s Nissan Leaf. It lacks the advanced liquid cooling systems found in newer models. Nissan has fixed this in the latest Leafs, but older ones often lose range faster, according to US research firm NimbleFins. Dunstan remains calm. “I charge both my EVs to 100% when I need to. I don’t overthink it,” he says.
The rise of battery testing technology
For drivers nervous about battery health, Austrian company Aviloo offers reassurance. “We can independently measure a battery’s state of health,” says Patrick Schabus, the firm’s chief product officer. Aviloo supplies certificates for British Car Auctions and sells two types of tests.
The premium version uses a small device that tracks performance over a few days as the battery drains from 100% to 10%. The quicker “flash test” reads data from the car’s battery system and analyses it in under two minutes.
The detailed test captures voltage and current changes, revealing the condition of each cell. Chief executive Marcus Berger says Aviloo’s results sometimes differ sharply from what cars report. He challenges the idea that batteries below 80% SOH are finished. “An EV with 75% can still be great,” he insists. “It just needs the right price.”
What real EV owners are learning
In New Zealand, Lucy Hawcroft bought a used Nissan Leaf with her husband three years ago. The dealer said its battery was 95% healthy. A year later, a mechanic found a significant drop. “My husband was a bit worried,” she says.
Still, the Leaf manages 160km per charge, enough for their short daily drives. “Our friends get around 400km,” she says. “That would be ideal.”
At Cleevely Electric Vehicles in Cheltenham, almost every buyer asks about battery condition. “It’s vital for them,” says sales director David Smith. The firm uses ClearWatt’s independent SOH reports. “We can’t alter the data,” he says. “Once customers see it, it helps most sales.” Managing director Matt Cleevely adds that partial repairs are often possible. “Replacing a few modules can save thousands compared to a new battery,” he explains.
Better batteries and smarter charging
How should EV owners charge to extend battery life? Stanford researcher Simona Onori says balance is best. “There’s probably a sweet spot between fast charging often and avoiding it completely,” she notes. But research continues.
Battery quality has improved dramatically. Max Reid from CRU says older batteries managed 500 to 1,000 charge cycles. “Now we’re seeing up to 10,000,” he says.
Even worn-out batteries find new lives. Paul Chaundy from Second Life EV Batteries in Dorset says many businesses reuse them for energy storage. Some charge forklifts when their grid can’t power all chargers at once.
Chaundy believes the industry needs more clarity. “We should have standard methods for testing and reporting battery health,” he says.
