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How to read an EV battery health certificate

Published 2026-10-21 · Last updated 2026-10-21

A battery certificate is the best evidence you'll get about a used EV's battery, as long as you know what you're looking at. This guide goes through the fields on the certificates UK and EU buyers see most often (AVILOO, Generational, Moba, DEKRA and Tesla's in-car test). It covers the difference that matters most and how to tell whether the number is good for that particular car.

The main certificates at a glance

Field lists are taken from each provider's own description and sample certificates, checked 2026-10-21. Layouts change and differ by vehicle. We are not paid by any of the providers mentioned on this page (see disclosure).

Field by field: what to look at

1. State of health (SoH)

Usable capacity now as a percentage of usable capacity when new. Treat small differences as noise: AVILOO gives a tolerance of ±3% (AVILOO GmbH), and ADAC gives ±3 percentage points for its AVILOO-based readings (ADAC). A car at 91% and one at 92% are effectively the same.

2. Two SoH numbers? Independent value vs the car's own (BMS) value

AVILOO certificates often print the BMS reading next to AVILOO's own figure. In the published certificates in our dataset, AVILOO's figure ranged from 2.2 points below to 2.9 points above the BMS value:

Single cars (n=1) – examples of the gap, not averages. AVILOO says the BMS value uses manufacturer-specific algorithms and can be too high or too low (AVILOO GmbH).

Check which kind of AVILOO report you have. An older AVILOO FLASH report format showed an AVILOO score out of 100 plus the BMS SoH, not an AVILOO-calculated SoH. For example, a UK dealer's MG4 EV report showed a score of 94/100 and a BMS SoH of 92.5% (Car360).

3. Capacity: usable vs nominal

Generational prints the capacity when new as two numbers, usable and nominal (Generational). Nominal (gross) capacity is bigger because some energy is kept in reserve. SoH is about the usable part. Some makers release reserve capacity as the battery ages, which is one reason the range readout can look stable even as the battery ages (Recurrent).

4. Range figures are estimates, not measurements

Generational's "real range" is calculated with its own model from real-world driving data (Northwest Vehicle Inspections). Moba's ranges come from its WLTP-based consumption model (Moba). AVILOO shows the WLTP figure when new, what similar cars typically achieve, and an estimate for this car (Battery Health Check). They're useful for comparing cars, but they don't guarantee what you'll get in winter on the motorway.

5. Benchmark or rating

The benchmark tells you whether the result is normal for that car, which the bare percentage can't. AVILOO compares the battery with cars of the same make, model, age and mileage (Battery Health Check). For example, a Swiss dealer's Škoda Enyaq certificate showed 92.1%, but AVILOO rated it below the average of comparable cars (Garage Lichtsteiner GmbH). You can do the same check with our model pages and the battery health estimator.

6. Cell voltage balance

This is the difference between the highest and lowest cell voltages, shown in mV on Generational certificates and on Moba's page 2 (Northwest Vehicle Inspections, Moba). In about 10,000 UK used-EV tests, the median spread was small. Roughly 1 in 85 cars was above 50 mV, which Generational says needs investigating, and about 1 in 200 was above 100 mV, a possible underlying fault (Generational, 2026-08-24). Generational's certificate advises that if the cells look unbalanced, you charge the car to full, wait at least 2 hours and test again (Northwest Vehicle Inspections). A single wide reading is a reason to retest, not proof of a fault.

7. Warranty block

Generational marks its warranty figures as "indicative only", based on duration, registration date and mileage (Northwest Vehicle Inspections). Confirm the cover with the manufacturer using the VIN. Our battery warranty checker lists the published terms for each model.

8. Test date, mileage and conditions

Check that the VIN matches the car and that the test is recent. The mileage on the certificate should be close to the odometer now. Test conditions matter: DEKRA's driving test needs a state of charge of about 40–80% and a battery temperature of 10–30 °C (DEKRA). Moba's page 2 records the outside temperature and state of charge during the test (Moba).

9. Verification

Scan the QR code or open the verification link, and compare the VIN, date and result online with the copy you were given. AVILOO's QR code opens the original on its own website (AVILOO GmbH). Generational treats its online certificate as the definitive version (Generational). A forwarded PDF or a screenshot you can't verify is weaker evidence.

What a certificate can't tell you

• It's a snapshot of the battery on the test day, not a prediction (AVILOO GmbH, Northwest Vehicle Inspections).
• Faults the car doesn't report through its diagnostic socket, such as mechanical damage, can't be detected. Faulty or manipulated control-unit data can also distort the result (AVILOO GmbH).
• It isn't a mechanical or electrical safety inspection of the whole car (Battery Health Check).

Is the number on the certificate good?

Compare it with data for the same model and mileage. Every model page lists sourced figures, and the comparison table puts 35 models side by side. Broad benchmarks across all EVs: ADAC expects at least 92% at 50,000 km, 88% at 100,000 km, 84% at 150,000 km, 80% at 200,000 km (ADAC). Arval: Ex-lease fleet, 24,000 certificates (Moba + AVILOO): about 93% average at 70,000 km; still above 90% at 160,000 km or 6 years; roughly 1 point lost per 25,000 km after a small early drop; newer generations 2–3 points higher. (Arval, 2026-02-25). TÜV NORD/Carly (BMS readings via OBD): Median SoH 96 across ~50,000 readings (BEV + PHEV); only 9.9% below 85. SoH fell about 0.7 points per 10,000 km up to ~90,000 km, then about 2.3 points per 10,000 km. Older cars differ by brand (Hyundai, Kia, Mercedes ~90–95+; older VW, Renault, Citroën ~70–80); current models mostly 97–100. (TÜV NORD GROUP with Carly).

Red flags

• No assessment ID, QR code or verification link, or the online record doesn't match (VIN, date, result).
• The test is old or was done many miles ago.
• Only a screenshot of an app reading, with no idea which tool or method produced it.
• No AVILOO Certified seal, or a mention of anomalies on the report. AVILOO generates a separate "Red Flag Report" when it detects anomalies (AVILOO GmbH).
• A large cell voltage difference that's still there after a full charge and a retest.
• Moba's page 2 missing when you asked for the full certificate.

Next steps: full used-EV battery checklist and test prices · Tesla Model 3 battery check · Chinese EVs battery guide.

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