Batteries have a habit of quietly getting worse. Anyone who has nursed an old smartphone through its final years knows the routine—it leaves the house at 100% and is begging for a charger by lunchtime. It’s no surprise, then, that one of the most common worries about <a https: alt="">
As a company specializing in battery diagnostics, Aviloo has developed what it calls the “FLASH” test, which is a 3-minute test performed on the battery via an EV’s OBD port. Rather than relying on a vehicle’s dashboard to report battery state of health, which would vary between manufacturers depending on methodology, the FLASH test is an independent test that is run the same way across The degradation figures suggest that the 70% threshold in most EV battery warranties, which typically run for eight years or 160,000 km, looks fairly safe for the majority of cars. No surprise, given that line was likely set after deep research by automaker engineering teams. Similar milestones show up in the UN’s Global Technical Regulation No. 22 on battery durability, which sets minimum requirements of 80% at five years or 100,000 km, and 70% at eight years or 160,000 km. Based on the Aviloo data, the 20 models tested are all, by and large, safely within those limits. The median figures only tell half the story, though. Aviloo also found big differences between individual cars of the same model at the same mileage. At 150,000 km, Model Ys varied by up to 11 percentage points, ID.4s by 11 to 12, and Ioniq 5s by more than 12. The Leaf had the widest spread of the lot at 13.5 points, which on a car with a fairly small pack works out to around 29 km of real-world range per charge. Pack size goes a long way to explaining the Leaf’s result. We measure wear in kilometres, but cells experience it in cycles. A 40 kWh Leaf needs roughly twice as many full charge cycles to cover 150,000 km as a car with a pack in the 75 kWh range, so every kilometre puts more wear on every cell. The Leaf famously also uses passive air cooling on its battery instead of an active liquid cooling system, which leaves its cells with less defence against heat and greater susceptibility to degradation. Fundamentally, there will always be variation between examples of the same model in the used car population. Differences in charging habits and usage will affect battery life, as will things like the ambient temperatures in the area the car lives. A car that is routinely driven to battery exhaustion and is stored in a hot climate at a high state of charge will always see a quicker loss of battery capacity than a car treated more gently in a mild climate. All of these variables make life awkward for anyone buying a used EV. Any two cars of the same model, year and mileage can have very different batteries, and there’s no way to tell by kicking the tyres. Aviloo’s reports make much the same point, noting that a buyer has no idea how a used EV’s battery has been treated. Ultimately, though, the message is that EV packs are, on the whole, lasting a lot better than our worst fears might have suggested. Losing ten percent of your range after 150,000 km isn’t nothing, but it’s a long way from the doom-laden scenarios that keep some people in petrol cars.
