These EVs retain their battery best, largest-ever study finds

The Mercedes EQA, Hyundai IONIQ 5, and BMW i4 hold onto their battery health better than any other electric car, according to the largest independent study of used-EV batteries ever run. That’s the ranking that falls out of 500,000-plus battery tests published by Austrian diagnostics firm AVILOO, which measured 20 popular EVs at up to 150,000 km (93,000 miles) of use. The EVs that hold their charge best AVILOO’s new AVILOO Certified EV Battery Report is built on physical measurements of the pack. For each model it calculated the median state of health (SoH) at 50,000 km, 100,000 km, and 150,000 km. SoH is the share of a battery’s original usable capacity that’s left, so a pack at 94% SoH still delivers roughly 94% of its original range. At 150,000 km, the mark that separates a durable pack from a tired one, the Mercedes EQA leads with a median SoH of 94%, just ahead of the Hyundai IONIQ 5 at 93.8% and the BMW i4 at 93.6%. The Hyundai Kona EV and Volvo XC40 Recharge round out the top five, both above 92.7%. The IONIQ 5 actually tops the chart at lower mileage, holding 97.1% at 50,000 km before the German pair catches it later. The takeaway for anyone shopping used: the best packs in this study are still north of 93% health after the equivalent of 93,000 miles. These batteries aren’t wearing out. Here’s how all 20 models rank by median SoH at 150,000 km: Model50,000 km150,000 kmMercedes-Benz EQA96.6%94.0%Hyundai IONIQ 597.1%93.8%BMW i495.6%93.6%Hyundai Kona EV96.3%93.0%Volvo XC40 Recharge95.2%92.8%Ford Mustang Mach-E95.1%92.5%Polestar 295.0%92.5%Cupra Born94.8%91.9%VW ID.394.6%91.8%Audi Q8 e-tron95.7%91.3%Skoda Enyaq iV95.1%91.0%VW ID.495.2%90.8%Peugeot e-20894.2%90.7%Vauxhall/Opel Corsa-e94.1%90.7%Audi Q4 e-tron95.0%90.6%Tesla Model Y94.4%90.3%Tesla Model 393.8%88.9%Renault Zoe91.6%87.3%MINI Cooper SE94.1%87.1%Nissan Leaf ZE191.2%86.7%Median state of health by model, from AVILOO’s FLASH Test data. Source: AVILOO Certified EV Battery Report. Small batteries and both Teslas bring up the rear The bottom of the table tells its own story. The Nissan Leaf (86.7%), MINI Cooper SE (87.1%), and Renault Zoe (87.3%) sit last, and they share a trait: small packs. A 40 kWh battery has to run through far more charging cycles to cover the same distance as a 78 kWh one, and those cycles show up as faster degradation. The Cooper SE is the sharpest faller in the whole study, dropping seven points of SoH between 50,000 and 150,000 km. Both Teslas land in the bottom third. The Model Y comes in at 90.3% at 150,000 km and the Model 3 at 88.9%, the second-worst result of any model with a battery its size. For the best-selling EVs on the planet, that’s a middling grade, and it undercuts the reputation Tesla has leaned on. It’s worth flagging that AVILOO’s newer data has been kinder to Tesla’s LFP packs, which held their charge better than the nickel-based Model 3 in a separate study. The good news is that while they performed worse, the margin is completely acceptable. The model average isn’t what you buy There’s a catch to any ranking like this, and AVILOO is open about it: the median is the midpoint, not the car in front of you. The gap between the best and worst individual examples of a single model runs as high as 13.5%, which is worth tens of kilometers of real-world range per charge. That means a “good” IONIQ 5 and a “bad” IONIQ 5 on the same lot are genuinely different products, and nothing on the window sticker tells you which is which. The dashboard SoH won’t either, because every automaker calculates it differently. It’s the same lesson from the 1,300-EV study where Kia and Tesla topped the list and from real-world data showing most EV batteries outlast the cars they’re in: batteries are aging well, but averages hide a lot. How AVILOO measured it The rankings come from AVILOO’s FLASH Test, a three-minute diagnostic that plugs into the OBD port and calculates SoH with a statistical model trained on hundreds of thousands of real used vehicles, rather than reading out the car’s own battery management system. The 500,000 tests here are a subset of a database AVILOO says has passed 1 million tests across North and South America, Europe, Australia, and Asia. Mercedes-Benz, Volvo, and Porsche Holding have named it their preferred independent battery-testing provider for European dealerships, and its methods are TUV and CARA certified. This summer it also launched a Battery Warranty across 12 European countries, paying out 2,700 pounds in the UK ($3,600) or 3,000 euros elsewhere if a car’s pack drops below an individual SoH floor within a year. Electrek’s Take The main takeaway here is that EV battery degradation is not a significant issue. I personally owned an EV with a battery pack that lasted more than 300,000 miles. It’s also important to note that battery degradation tends to slow down over time and mileage – meaning that the first 100,000 miles is where you see the biggest drop. Even the worst-performing EVs in this list have somewhat acceptable battery degradation. If you’re shopping for a used EV, the cheapest way to run one is on your own electrons. Home solar can cut the cost of charging to nearly nothing. With electricity rates up almost 10% last year and expected to keep climbing, going solar is one of the best ways to protect yourself against rising costs. And with lease and PPA options, you can do it with zero upfront cost and start saving immediately. If you want to find the best deal, check out EnergySage. It’s a free service with hundreds of pre-vetted installers competing for your business, so you save 20 to 30% compared to going it alone. No sales calls until you pick an installer. Get your free quotes here. FTC: We use income earning auto affiliate links. More.