Battery data specialist Aviloo has launched the Aviloo Certified EV Battery Report, an independent study of battery health in used electric vehicles that analyzes over 500,000 independent tests carried out on used EVs between 2022 and 2026, covering 20 popular EV models.
The report draws on a subset of Aviloo’s broader diagnostic database, which now spans more than one million independent tests worldwide across North and South America, Europe, Australia and Asia, to detail how battery health varies in used electric vehicles, and how different climates affect battery health and charging performance.
How the report works
The Aviloo Certified EV Battery Report, which will be published twice a year going forward, is built on data from used electric vehicles tested via its independent Aviloo Flash Test. For each model, Aviloo calculates the median state of health at three mileage milestones, 50,000km, 100,000km and 150,000km, along with the range expected to cover 99% of vehicles at each point†.
State of health (SoH), the percentage of a battery’s original usable capacity that remains, is the clearest single measure of how a used EV’s battery has aged; a battery at 95% SoH still delivers roughly 95% of its original range per charge.
Reading the data
Comparing the three mileage snapshots side by side reveals three consistent patterns. First, median battery health drops as mileage increases. Second, the spread between individual cars widens with distance – degradation is real, and it grows the further a car travels. Third, and just as importantly, there are consistent differences between models at every mileage point.
Four EVs, four different battery stories
Aviloo data shows that used Tesla Model Ys with 78.8kWh batteries have a median SoH of 94.5% at 50,000km, falling to 90.3% at 150,000km. This corresponds to a real-world range of around 379km per charge at 50,000km and 362km at 150,000km. However, individual vehicles vary by up to 11 percentage points in SoH across this mileage range, equivalent to around 46km of real-world range, highlighting the variation in battery degradation between vehicles.
Median battery SoH for the 77kWh Volkswagen ID.4 – which sold around 40,000 units in Europe in the first half of 2025 – falls from 95.3% at 50,000km to 90.6% at 150,000km, corresponding to a real-world range of around 373km per charge, decreasing to roughly 354km. At higher mileages, individual vehicles vary by up to 11–12 percentage points in SoH, equivalent to around 45km of real-world range per charge.
Aviloo data shows that the 72.6kWh Hyundai Ioniq 5 has a median SoH of 97.2% at 50,000km, falling to 92.8% at 150,000km. This corresponds to a real-world range of around 335km per charge, decreasing to roughly 319km. At 150,000km, the difference between individual vehicles exceeds 12 percentage points in SoH, equivalent to around 42km of real-world range per charge.
The 40kWh Nissan Leaf ZE1 has the smallest battery capacity of the four models, at around half that of the others. Aviloo data shows that its median SoH falls from 91.1% at 50,000km to 86.3% at 150,000km, the lowest of the four models across both mileages. It also has the widest variation between individual vehicles, reaching up to 13.5 percentage points in SoH at 150,000km, equivalent to around 29km of real-world range per charge.
In real-world terms, that median SoH corresponds to around 196km of range per charge at 50,000km, falling to roughly 185km at 150,000km. This is markedly less than the other three models, reflecting the Leaf’s smaller battery capacity and making it better suited to shorter, more local journeys. The Leaf remains the world’s first mass-market EV, with more than 650,000 units sold worldwide. Its data provides a clear illustration of how battery capacity and charging frequency can affect real-world range and degradation, and highlights the value of independent battery testing.
Why a small gap in state of health matters more than it sounds
As the examples show, a difference of 10 percentage points or more in SoH can translate into tens of kilometers of real-world range per charge. This can mean the difference between completing a long journey without stopping and requiring an additional charging stop. For consumers, dealers and lenders assessing a used EV, this information can provide a more accurate picture of a vehicle’s condition than a single average figure for the model.
Why climate matters and why global data matters more
Battery health is not determined by mileage alone. Temperature affects both the chemistry of degradation and how quickly a battery can accept charge, with cooler climates potentially slowing charging and influencing wear patterns compared with warmer conditions. Aviloo’s global dataset accounts for this variation, with the Aviloo Certified EV Battery Report drawing on independent tests from North and South America, Europe, Australia and Asia. This provides data across a range of climates and driving conditions, rather than reflecting the experience of a single country or region.
Why this matters for the used-EV market
Buyers of used petrol or diesel cars have long relied on mileage readings and MOT histories to assess condition; consumers, dealers and fleets buying a used EV need an equivalent measure for the battery – the car’s most expensive component and, as this report shows, one whose condition can vary significantly between vehicles.
Marcus Berger, CEO of Aviloo, said, “The truth in this data is that averages hide a lot. Yes, EV batteries are ageing better than the ‘they wear out fast’ myth suggests – but that’s not the most useful thing this report tells you. What matters is that battery health varies significantly between models, and even more between individual cars of the same model. A gap of 10% or 15% in state of health is a real difference in range, in what a car is worth, and in what you can rely on it for. You simply can’t know where your car sits in that range without testing it independently.
“That’s why we built the Aviloo Flash Test, and why we’re now publishing this Aviloo Certified EV Battery Report twice a year – to give the whole market, from individual buyers to fleets and insurers, an honest, independent and genuinely global picture of how these batteries perform.”
The Flash Test
Aviloo’s Flash Test is an independent three-minute diagnostic performed via the vehicle’s OBD port. It provides a battery health assessment for an individual used vehicle rather than relying on an average for the model, giving an independent measure to assess battery condition alongside the information provided by the vehicle’s dashboard.
The Aviloo Flash Test uses independent measurement to assess battery health rather than relying solely on the vehicle’s own reporting. Aviloo calculates state of health using a statistical model trained on data from hundreds of thousands of used vehicles. The model considers the vehicle’s internal battery health assessment alongside mileage, age, charge cycles, cell-voltage spread, energy counts and other diagnostic signals.
Explore: Tony Mancina, Stellantis Canada
†: Methodology: for each vehicle model, independent Aviloo FLASH-test data is used to produce a statistical distribution of State of Health at each mileage point. The distribution is found by fitting multiple quantile curves, including the median, to the data.