Two used Hyundai IONIQ 5s with the same 150,000 km on the clock can differ by more than 12 percentage points in battery health. That is roughly 42 km of range on a full charge, or 26 miles. It is the detail buried under a more comforting headline from a new analysis of more than 500,000 independent battery tests: most electric car batteries hold close to 90% of their original usable capacity at 150,000 km, or 93,000 miles.
The analysis comes from AVILOO, a battery diagnostics firm, in its first Certified EV Battery Report. It covers tests carried out between 2022 and 2026 on 20 popular models, and it argues that fears of EV batteries wearing out quickly are misplaced. State of Health, the share of original usable capacity left, varied by as much as 13.5 percentage points among cars of the same model and mileage.
Four cars, four answers
At 150,000 km, median health ranged from 86.3% for the 40kWh Nissan Leaf ZE1 to 92.8% for the 72.6kWh IONIQ 5. The Volkswagen ID.4 reached 90.6% and the Tesla Model Y 90.3%.
The IONIQ 5 slipped from 97.2% at 50,000 km, which AVILOO translates into real-world range falling from about 335 km to 319 km. The ID.4 went from 95.3% to 90.6%, about 373 km down to 354 km. The Model Y dropped from 94.5%, with range sliding from 379 km to 362 km. The Leaf went from 91.1% to 86.3%, from about 196 km to 185 km. Gaps between individual cars reached 11 to 12 points for the ID.4 and 11 for the Model Y, which could mean 45 km and 46 km of range respectively.
AVILOO says the four were picked to show different battery sizes and types, not to rank the models. It links the Leaf’s faster fade partly to its small pack, which needs more charging cycles to cover the same distance. Even so, the median Leaf kept more than 86% of its capacity, a fair rebuttal to the idea that older EVs routinely need new batteries.
Why averages mislead
“The truth in this data is that averages hide a lot,” said Marcus Berger, AVILOO’s chief executive. “What matters is that battery health varies significantly between models, and even more between individual cars of the same model. A gap of ten or fifteen per cent 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.”
Data came from North and South America, Europe, Australia and Asia, so heat and cold both feature. The tests use AVILOO’s three-minute FLASH Test through the car’s diagnostic port, and the company uses statistical models rather than simply repeating the figure the car reports. That makes it a model-based estimate, not a full charge-and-discharge measurement, and the report lumps together different battery sizes within each model range.
AVILOO says its database now holds more than one million tests and it plans two updated reports a year. It has also launched a one-year battery warranty in several European markets, including the UK, where the payment is £2,700 if a car’s battery falls below an individually calculated minimum over 20,000 km.
