Used electric vehicle batteries may be aging far better than buyers fear. Aviloo has released what it describes as the world’s largest independent analysis of second-hand EV batteries, drawing on more than 500,000 diagnostic tests across 20 models between 2022 and 2026. At the centre of the Used EV Battery Health Study is a reassuring finding: cars with 150,000 km commonly retain 87% to 94% of their original usable capacity.
However, the research also exposes major differences between models and individual vehicles, reinforcing why independent testing matters before buying, valuing, or warranty-covering a high-mileage electric car in the used market.
The Used EV Battery Health Study found that most tested electric cars retained between 87% and 94% of their original battery capacity after covering 150,000 km. However, battery condition varied considerably between models and even between identical vehicles, making an independent diagnostic test more dependable than mileage, dashboard estimates, or model averages alone.
World’s Largest Independent Used-EV Battery Analysis
The Aviloo Certified EV Battery Report is based on more than 500,000 tests conducted from 2022 to 2026 across 20 widely used electric vehicle models.
This dataset is part of Aviloo’s global database of more than one million independent battery tests. The company’s diagnostic activity covers vehicles across Europe, North America, South America, Asia, and Australia.
Aviloo plans to publish the report twice a year, potentially providing buyers, dealers, leasing businesses, and fleet operators with a regularly updated benchmark for assessing used electric-car batteries.
Report highlights at a glance
- More than 500,000 battery tests included in the report
- Data collected between 2022 and 2026
- 20 popular EV models assessed
- Battery health measured at 50,000 km, 100,000 km and 150,000 km
- Expected health range calculated to cover 99% of vehicles
- Broader database includes over one million global tests
- Mercedes EQA, Hyundai IONIQ 5, and BMW i4 named among the strongest capacity-retaining models
- New editions of the report planned twice annually
What the Used EV Battery Health Study Reveals
The data exposes three clear patterns in electric-car battery aging.
First, the median battery State of Health declines as mileage increases. This is expected because lithium-ion batteries gradually lose usable capacity through driving, charging, and calendar aging.
Second, differences between individual vehicles become wider at higher mileages. Two examples of the same EV model can therefore have noticeably different remaining capacities, depending on their climate, charging behavior, thermal conditions, and operating history.
Third, consistent performance differences appear between individual models and battery architectures. Vehicles equipped with effective liquid-cooling systems generally deliver more stable results than air-cooled models, particularly in warmer climates.
These findings challenge the idea that mileage alone can accurately indicate an EV battery’s remaining life.
What Does Battery State of Health Mean?
State of Health, commonly abbreviated as SoH, measures the percentage of a battery’s original usable capacity that remains.
For example, an electric car with 95% SoH retains approximately 95% of the usable battery capacity it had when new. Under similar driving and environmental conditions, it should therefore provide roughly 95% of its original range per charge.
However, SoH is not displayed consistently across electric vehicles. Dashboard estimates can also be influenced by recent driving style, temperature, and energy consumption. A physical diagnostic assessment can offer buyers a clearer picture of the battery’s actual condition.
Four Popular EVs Tell Four Different Battery Stories
The Tesla Model Y retains over 90% at 150,000 km.
Tesla Model Y vehicles equipped with a 78.8 kWh battery recorded a median SoH of 94.5% at 50,000 km. That figure declined to 90.3% at 150,000 km.
The estimated real-world range consequently fell from approximately 379 km to 362 km per charge.
However, individual Model Y vehicles showed a difference of up to 11 percentage points in SoH across the measured mileage range. That variation represents approximately 46 km of real-world driving range.
The Volkswagen ID. 4 shows steady capacity retention.
The 77 kWh Volkswagen ID.4 recorded a median battery health of 95.3% at 50,000 km and 90.6% at 150,000 km.
Its estimated real-world range declined from around 373 km to 354 km per charge.
At higher mileages, the gap between individual ID.4 vehicles reached approximately 11 to 12 percentage points in SoH—equal to nearly 45 km of real-world range. The model’s relevance to the European used-car market is significant, following sales of approximately 40,000 units in Europe during the first half of 2025.
The Hyundai IONIQ 5 emerges as a strong performer.
The Hyundai IONIQ 5 with a 72.6 kWh battery delivered one of the report’s strongest results. Its median SoH stood at 97.2% after 50,000 km and remained at 92.8% after 150,000 km.
Estimated real-world range declined moderately from around 335 km to 319 km per charge.
Nevertheless, the health difference between individual IONIQ 5 vehicles exceeded 12 percentage points at 150,000 km. This could create a real-world range gap of approximately 42 km between two apparently similar used examples.
The Nissan Leaf records faster degradation.
The 40 kWh Nissan Leaf ZE1 recorded the lowest median battery health among the four highlighted models.
Its median SoH declined from 91.1% at 50,000 km to 86.3% at 150,000 km. Estimated real-world range fell from approximately 196 km to 185 km per charge.
At 150,000 km, individual Leaf vehicles varied by as much as 13.5 percentage points in battery health—the widest gap among the four models. This difference represented approximately 29 km of usable real-world range.
The Leaf uses an air-cooled battery and has a substantially smaller pack than the other highlighted vehicles. Its results demonstrate how battery size, temperature management, and charging frequency can influence degradation and everyday usability.
Despite its shorter range, the Leaf remains historically important as the world’s first mass-market electric car, with more than 650,000 units sold globally.
Why Identical Used EVs Can Have Different Battery Health
One of the report’s most important findings is that model, age, and mileage cannot reveal the complete battery story.
Battery health can be affected by:
- Exposure to extremely hot or cold climates
- Battery cooling and thermal-management design
- Frequency of rapid DC charging
- Time spent at very high or very low charge levels
- Driving intensity and annual mileage
- Long periods of storage
- Differences in battery chemistry and pack architecture
This explains why two electric cars of the same age, model, and mileage can offer noticeably different remaining range and long-term value.
How Aviloo’s Three-Minute Battery Test Works
The report uses data generated through the proprietary Aviloo Flash Test. The three-minute diagnostic connects to the vehicle through its onboard diagnostics or OBD port.
Instead of relying solely on the battery management system’s internal estimate or the range shown on the dashboard, the test independently evaluates battery data to determine its condition.
Aviloo has also expanded its certified battery warranty programme across 26 European countries. Qualifying health assessments can be supported by financial guarantees, helping increase confidence in used-EV transactions.
What This Means for Used-EV Buyers
The results offer encouraging evidence that high mileage does not automatically make an electric car’s battery unsuitable.
Many vehicles still retain a substantial majority of their original capacity at 150,000 km. However, the growing health variation at higher mileages means buyers should assess the individual vehicle rather than rely on a general reputation for the model.
Before buying a used electric car, consumers should:
- Request an independent battery health certificate
- Compare current SoH with the model’s expected benchmark
- Check the estimated remaining range
- Review rapid-charging and service history where available
- Ask whether the battery warranty is transferable
- Consider the vehicle’s previous climate and usage conditions
- Avoid judging battery condition from mileage alone
Final Verdict
The Used EV Battery Health Study delivers encouraging news for the second-hand electric-car market: most EV batteries appear to retain useful capacity far longer than many consumers expect.
Yet the differences between models—and especially between individual cars—remain too large to ignore. With SoH variations reaching 13.5 percentage points among comparable vehicles, an independent battery test could become as important to a used-EV purchase as checking accident history, service records, and mechanical condition.
Aviloo’s data suggests that used electric cars can remain practical well beyond 150,000 km, but the battery health of the specific vehicle should determine its true range, value, and buying risk.
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