Battery health can vary significantly between used electric vehicles of the same model, with differences of up to 13.5% recorded in a new study of more than 500,000 battery tests.
Independent electric vehicle battery diagnostics company AVILOO has released its first Certified EV Battery Report, based on tests conducted between 2022 and 2026 across 20 popular EV models.
The data comes from vehicles in North and South America, Europe, Australia and Asia and forms part of AVILOO’s database of more than one million battery tests and claims to be the world’s largest independent study of battery health in used electric vehicles.
The report measures battery State of Health (SoH), which represents the percentage of a battery’s original usable capacity remaining, at 50,000km, 100,000km and 150,000km.
It found median battery health generally declined as mileage increased, while differences between individual vehicles tended to widen.
Four models highlighted in the report illustrate the variation.
The Tesla Model Y with a 78.8kWh battery recorded median SoH of 94.5% at 50,000km and 90.3% at 150,000km. Individual Model Ys varied by as much as 11 percentage points in SoH, equivalent to about 46km of real-world range per charge.
The Volkswagen ID.4 with a 77kWh battery fell from a median 95.3% at 50,000km to 90.6% at 150,000km, while the Hyundai IONIQ 5 recorded 97.2% and 92.8% respectively.
The 40kWh Nissan Leaf ZE1 showed greater degradation, with median SoH falling from 91.1% at 50,000km to 86.3% at 150,000km. It also recorded a spread of up to 13.5 percentage points between individual vehicles at the higher mileage.
AVILOO says smaller-battery EVs tend to undergo more charging cycles to travel the same distance, which can contribute to faster degradation.
Chief executive Marcus Berger says the results show averages alone are not enough to determine the condition of an individual used EV.
“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.”
AVILOO uses its three-minute FLASH Test, connected through a vehicle’s on-board diagnostics (OBD) port, to assess battery health rather than relying solely on the vehicle’s own battery management system reading.
The company says the growing used-EV market makes independent battery assessment increasingly important for buyers, dealers, fleets, lenders and insurers because the battery is one of an EV’s most expensive components.
