When Kerry Dunstan and his partner began searching for an electric car this summer, one question ruled their decision: “How’s the battery?” They found a 2021 Nissan Leaf with 29,000 miles. The dealer said its state of health (SOH) was 93%. That was enough to convince them. For £12,500, they bought a spacious, practical electric car with room for passengers and luggage.
Dunstan, a cabinetmaker who also owns a sleeker electric Volvo SUV, admits the Leaf doesn’t thrill him. “I like cars with energy and style – this one’s a bit bland,” he says. Still, he’s satisfied. “It has performed exactly as I expected,” he adds.
Battery health now drives the used EV market
Used car buyers once focused on mileage and age. Today, battery condition is the most important factor. Shoppers ask how it was treated. Was it fast charged to 100% often? Frequent fast charging can reduce battery life.
This uncertainty makes some hesitant about second-hand EVs. But new analytics companies claim they can measure battery health accurately. Experts also note that many EVs last longer than early predictions suggested.
Dunstan’s Leaf illustrates this point. It lacks the liquid cooling system of newer models. Nissan fixed this in later generations, but older Leafs lose range faster, according to US research firm NimbleFins. Dunstan is unconcerned. “I charge both my EVs when needed,” he says. “I don’t overthink it.”
Testing technology uncovers the truth
Austrian firm Aviloo helps buyers measure a battery’s real condition. “We can independently determine a battery’s state of health,” says chief product officer Patrick Schabus. Aviloo provides certificates for British Car Auctions and offers two types of tests.
The premium test uses a small device that tracks the battery over several days as it discharges from full to nearly empty. The quicker “flash test” reads data from the car’s software and delivers a report in minutes.
The premium test detects voltage and current changes, highlighting weak cells. Chief executive Marcus Berger says Aviloo’s readings often differ from the car’s own data. He also challenges the belief that batteries below 80% SOH are useless. “A car with 75% health can still perform well – it just needs the right price,” he says.
What drivers are learning
In New Zealand, Lucy Hawcroft bought a Nissan Leaf three years ago with her husband. The dealer said the battery had 95% health. A year later, an independent mechanic found a noticeable drop. “My husband was a bit concerned,” she recalls.
Even so, the Leaf still drives about 160km per charge. They mostly use it for short 10km trips. “Some friends get 400km,” she says. “That would be ideal.”
At Cleevely Electric Vehicles in Cheltenham, battery checks are now routine. “Most customers ask for them,” says sales director David Smith. The company uses ClearWatt’s independent SOH reports. “We can’t change the results,” he says. “Once buyers see them, nine out of ten sales go through.” Managing director Matt Cleevely adds that many battery issues are fixable. “Replacing a few modules can save thousands compared to a full pack,” he explains.
Smarter charging and longer life
How should EV owners charge to preserve battery life? Stanford researcher Simona Onori says moderation is key. “There’s likely a sweet spot between frequent fast charging and avoiding it completely,” she explains. Research is still ongoing.
Battery technology has improved quickly. Max Reid from CRU says older EV batteries lasted 500 to 1,000 cycles. “Some new cells now reach 10,000,” he says.
Even retired EV batteries have value. Paul Chaundy from Second Life EV Batteries in Dorset says many companies reuse them for energy storage. Some use old EV batteries to power forklifts when the grid can’t handle multiple chargers.
Chaundy believes standardisation is essential. “We need clear, shared rules for testing and reporting battery health,” he says.
