When Kerry Dunstan and his partner went looking for a new car this summer, they focused on one question: “How’s the battery?” They found a 2021 Nissan Leaf with 29,000 miles, and the dealer told them the battery’s state of health (SOH) was still 93%. That sealed the deal. For £12,500, they bought a spacious, practical electric vehicle with plenty of room.
Dunstan, a cabinetmaker who also owns a sleek electric Volvo SUV, admits the Leaf doesn’t thrill him. “I like cars with flair – this one’s a bit plain,” he says. Still, he’s satisfied. “It’s done exactly what I expected,” he adds.
Why battery health drives today’s used car market
In the old days, buyers checked age and mileage. Now, they ask about battery health first. It’s the single most important factor for anyone buying a used EV. How often was it charged? Did the previous owner use fast charging too much? Those habits can shorten a battery’s life.
This uncertainty has scared off some buyers. But a new generation of analytics firms promises accurate insights into battery condition. Experts say some EVs are lasting far longer than early predictions suggested.
Take Dunstan’s Leaf. It lacks the advanced liquid cooling systems found in newer EVs. Nissan fixed that in recent versions, but older Leafs often lose range faster, according to US data firm NimbleFins. Dunstan isn’t worried. “I charge both my EVs to 100% when I need to. I don’t stress about it,” he says.
The technology revealing battery secrets
To ease buyers’ fears, Austrian company Aviloo claims it can measure battery health with precision. “We can determine the state of health completely independently,” says chief product officer Patrick Schabus. Aviloo, which works with British Car Auctions, offers two testing options.
The premium test uses a small data box that monitors the car for several days as the battery drains from full to nearly empty. The quicker “flash test” reads data directly from the car’s system and analyses it within minutes.
The premium test captures small fluctuations in voltage and current, giving insight into individual cells. Chief executive Marcus Berger says their data often differs from what cars report. He also challenges the belief that a battery below 80% SOH is finished. “A car with 75% health can still be great – if priced fairly,” he says.
What owners around the world experience
In New Zealand, Lucy Hawcroft and her husband bought a Nissan Leaf three years ago. The dealer said its battery had 95% health. A year later, a mechanic tested it again and found a clear drop. “My husband was a bit worried,” she says.
Despite that, the Leaf still drives 160km on a full charge. The couple mostly use it for short 10km trips. “Friends of ours get 400km,” she says. “That would be perfect.”
At Cleevely Electric Vehicles in Cheltenham, customers now expect detailed battery reports. “Most buyers ask about it,” says sales director David Smith. His firm uses ClearWatt’s independent SOH tests. “We can’t change the results,” he says. “Once people see the report, it helps close the sale.” Managing director Matt Cleevely adds that partial repairs can save money. “Replacing a few cells is often far cheaper than a new battery,” he says.
Smarter charging and longer battery life ahead
How should EV owners charge their cars? According to Stanford researcher Simona Onori, the best approach lies in moderation. “There’s a sweet spot between fast charging often and avoiding it completely,” she explains. Scientists are still studying exactly where that balance lies.
Battery technology, however, is advancing quickly. Max Reid from CRU says older EV batteries lasted between 500 and 1,000 charge cycles. “New cells now reach up to 10,000,” he says.
Even when a battery no longer suits an EV, it can still be valuable. Paul Chaundy from Second Life EV Batteries in Dorset says companies repurpose used EV batteries for power storage. Some charge forklifts when their grid can’t handle all the chargers at once.
Chaundy believes the industry now needs clear standards. “We should have one transparent method for measuring and reporting battery health,” he says.
