When Kerry Dunstan and his partner started looking for an electric car this summer, one question topped their list: “How’s the battery?” They discovered 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, roomy electric car with space 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 plain,” he says. Still, he’s happy. “It has performed exactly as I expected,” he adds.
Battery health now drives used EV purchases
Used car buyers once focused on mileage and age. Today, battery condition is the most important factor. Buyers want to know how the battery was treated. Was it fast charged to 100% frequently? That can shorten its lifespan.
This uncertainty makes some hesitant about second-hand EVs. But battery analytics firms say they can measure battery health accurately. Experts also note that many EVs last longer than early predictions suggested.
Dunstan’s Leaf illustrates the point. It lacks the liquid cooling systems of newer models. Nissan added 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 reveals real battery condition
Austrian company Aviloo helps buyers assess battery health. “We can independently determine the 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 tracks voltage and current, identifying weak cells. Chief executive Marcus Berger says Aviloo’s readings often differ from the car’s own numbers. He also challenges 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 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 reported 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 can be fixed. “Replacing a few modules is often much cheaper than a full pack,” he explains.
Smarter charging extends battery life
How should EV owners charge to protect the battery? Stanford researcher Simona Onori says moderation is key. “There’s likely a sweet spot between frequent fast charging and avoiding it completely,” she explains. More research is needed.
Battery technology has improved quickly. Max Reid from CRU says older EV batteries lasted 500 to 1,000 cycles. “Some of the latest cells now reach 10,000,” he says.
Even retired batteries still have value. Paul Chaundy from Second Life EV Batteries in Dorset says companies repurpose them for energy storage. Some power electric forklifts when the grid cannot handle multiple chargers.
Chaundy believes industry standards are overdue. “We need clear, shared rules for testing and reporting battery health,” he says.
