When Kerry Dunstan and his partner went looking for an electric car this summer, one question led the way: “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 convinced them. For £12,500, they bought a practical, spacious EV with room for passengers and luggage.
Dunstan, a cabinetmaker who also owns a stylish electric Volvo SUV, admits the Leaf doesn’t excite him. “I like cars with energy and character – this one’s a bit flat,” he says. Still, he’s satisfied. “It has performed exactly as I expected,” he adds.
Battery health drives the used EV market
Used car buyers once focused on mileage and age. Today, battery condition defines a used EV’s value. Shoppers want to know how the battery was treated. Was it frequently fast charged to 100%? That can reduce its lifespan.
This uncertainty makes some hesitant about second-hand EVs. But battery analytics companies claim they can measure real battery health accurately. Experts also say many EVs last longer than early predictions suggested.
Dunstan’s Leaf illustrates this. 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 remains unconcerned. “I charge both my EVs when needed,” he says. “I don’t overthink it.”
Testing technology reveals the truth
Austrian firm Aviloo offers clarity for buyers. “We can independently measure 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 battery performance over several days as it discharges from full to nearly empty. The faster “flash test” reads data from the car’s software and produces a report in minutes.
The detailed test monitors voltage and current fluctuations, revealing weak cells. Chief executive Marcus Berger says Aviloo’s readings often differ from the car’s own display. He also rejects the idea that batteries below 80% SOH are useless. “A car with 75% health can still perform well – it just needs the right price,” he says.
Lessons from real EV owners
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 on a full charge. They mostly use it for short trips under 10km. “Some friends get 400km,” she says. “That would be ideal.”
At Cleevely Electric Vehicles in Cheltenham, battery checks are 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 issues are fixable. “Replacing a few modules is far cheaper than a full battery,” he explains.
Smarter charging extends battery life
How should EV owners charge to protect their battery? Stanford researcher Simona Onori says moderation is key. “There’s a sweet spot between frequent fast charging and avoiding it completely,” she explains. More research is needed.
Battery technology has improved rapidly. Max Reid from CRU says older EV batteries lasted 500 to 1,000 cycles. “Some of the newest cells now reach 10,000,” he notes.
Even retired batteries still have value. Paul Chaundy from Second Life EV Batteries in Dorset says companies reuse them for energy storage. Some power electric forklifts when the grid cannot handle multiple chargers.
Chaundy says standardisation is crucial. “We need clear, shared rules for testing and reporting battery health,” he says.
