How to know the health of the battery in a used electric car

When Kerry Dunstan and his partner set out to buy a new electric car this summer, one of the questions they asked was: “How’s the battery?”

They found a 2021 Nissan Leaf with only 29,000 miles, and the dealer told them the battery condition, or state of health (SOH), was still around 93%.

The couple was sold. For £12,500, they got an electric car with a big boot and plenty of space for passengers.

Although Mr. Dunstan, the cabinet maker who also owns the somewhat sleeker Volvo electric SUV, hasn’t quite fallen in love with the old Leaf.

“I like jazzy sports cars, which is kind of weird,” he says.

However, he adds that the Leaf performed exactly as expected during the three months they owned them.

It used to be that age and mileage were the main details scrutinized by potential buyers of used cars. But as more people switch to electric cars, checking the health of a car’s battery has become more important.

How was that battery treated? Did the last owner regularly charge it to 100%, for example? Which It has the ability to shorten Electric car battery life.

This is a battery black box problem Some consumers have developed Stop buying a used electric car. But battery analysis companies say they can detect the condition of an old electric car’s battery with high accuracy. Industry experts say some EVs are lasting longer than many expected.

Take Mr. Dunstan’s Nissan Leaf. This is a model of electric car that is designed without the sophisticated liquid-based battery cooling system common to many other electric cars. While April This has been corrected in the last generation From the Leafs, previous models show a significant shortening of their range year after year, According to the data It was analyzed by the American insurance and research company NimbleFins.

Mr. Dunstan is unfazed. “I charge my electric cars 100% and charge them when I need to charge them – I don’t have to worry about it,” he says.

However, for people looking for used electric cars who are worried about the battery, Austria-based Aviloo says it has a solution. “We can really, completely independently, determine the health of the battery,” says Patrick Shabos, chief product officer.

Aviloo is one of many companies specializing in battery analysis on the market. The company, which provides battery health certificates to major British car auctions in the UK, offers two products.

There’s a distinct test where EV owners plug a data logger box about the size of an eyeglass case into their car so it can monitor battery performance as they use the car over the course of a few days, starting from 100% charge all the way down to 10%.

Or they can opt for a faster flash test, which uses a different box to suck in data from the car’s battery management software and then analyze it with the help of a computer model. “We can do it at a standstill in less than two minutes,” Shabbos says.

Avello says the premium test closely monitors battery discharge, picks up fluctuations in current or voltage, and can reveal additional detailed information about the health of individual cells in the battery.

Avello CEO Markus Berger says his company’s analytics results sometimes differ “significantly” from the battery SOH percentages produced by the analytics systems built into some cars.

Challenges Conventional wisdom That batteries with a SOH below 80% are pretty much out of date: “An EV that is healthy below 80% can still be a great car…it just needs to be priced [appropriately]”.

In New Zealand, electric car owner Lucy Howcroft, who works in sustainability at an infrastructure company, bought a Nissan Leaf with her husband about three years ago. She recalls getting an SOH score of 95% or so from the agency. But a year later an independent mechanic checked the SOH again.

“It went down a little bit,” she recalls. “My husband was a little surprised or worried about it.”

However, the car still has a range of about 160 kilometers (100 miles) when fully charged. The couple mostly uses it for short trips of up to 10 km. Ms Howcroft says she has friends who have much greater ranges for their electric cars, up to around 400km: “That would be ideal.”

For David Smith, sales director at Cleevely Electric Vehicles in Cheltenham, being able to analyze used electric vehicle batteries in detail is a deal maker. Most clients ask for this information, he says. His company uses SOH reports from ClearWatt, another battery analysis company.

“They are completely independent,” he says. “We cannot interfere in the reporting.” “Once customers see the report, it helps the sale nine times out of 10.”

Matt Cleevely, managing director of Cleevely Electric Vehicles, adds that it is often possible to replace groups of cells or modules within a battery pack – which is much cheaper than installing a whole new battery.

As for how to charge your electric car in order to best care for its battery, Simona Onori of Stanford University says: “There’s probably a sweet spot between frequent fast charging and avoiding it altogether.” However, she adds that, to her knowledge, this has not yet been comprehensively studied.

Despite some consumer caution, battery technology has improved significantly in recent years, says Max Read, head of battery costs at market research firm CRU. “Older batteries may last maybe 500 to 1,000 [charging] “He explains.” “Now, there are 10,000 cycles coming out in some new EV cells.”

Batteries that are no longer good enough to power the electric vehicle they were designed for can still be useful, says Paul Chundy of Second Life EV Batteries in Dorset. For example, some of his clients are companies that use former electric car batteries to store electricity on their premises. They may have, for example, six electric forklifts but the grid connection is only large enough for charging ports to power two or three of the forklifts.

Regarding the various methodologies that auto manufacturers use to prepare occupational safety and health reports for their own vehicles, Mr. Chundy says: “I think we need more standards around that.”