EV battery certificate: How to read the report

A battery certificate helps when buying a used EV if you can identify which car was tested, when and by which method. Ask for the full report before judging a percentage.

Here is an entirely fictional example: a listing says “90 percent battery health.” But the image you receive shows only that number. You still do not know whether it belongs to the car on offer, when it was recorded or what it refers to. Your next task is to get those details.

Ask for every page, including the explanation of the result. AVILOO, for example, distinguishes between a short preview for listings and the full report. The provider also describes a QR code that opens the original digital version. (AVILOO)

Compare the report number, vehicle details and result there with the version you received. Privately check the vehicle identification number, or VIN, against the car and its documents. Do not publish it when seeking help.

If you cannot clearly match the report to the car, ask the issuer to clarify. A report for a similar model does not answer your question about this car.

The provider’s name is not enough: the same provider may use different methods.

ADAC describes a driving-based AVILOO test: a box connected to the diagnostic port records data during a drive from fully charged to below ten percent, without charging in between. The report states the energy that can be drawn from the battery relative to its new condition and includes data from the test drive. This describes that test procedure; it is not an instruction to conduct your own discharge test. (ADAC)

AVILOO explains that its PREMIUM test records current, cell voltages and temperature, among other data, during the drive. For the FLASH quick test, the provider describes a calculation model trained using PREMIUM tests; a full discharge is not needed. These are the test provider’s descriptions of its own methods. (AVILOO)

Record the exact test name. Then check whether the report answers the question that matters to your purchase. The heading “battery certificate” alone does not make different methods comparable.

SoH stands for “State of Health”: the battery’s condition relative to when it was new. AVILOO distinguishes, among other things, between results based on amp-hours and those based on kilowatt-hours, and notes that calculation methods differ. (AVILOO)

Look for the definition in the report. Does the number describe energy that can be drawn from the battery? What new-condition value is used as the reference? Does the report also give a value in kilowatt-hours, or kWh?

Do not simply multiply an unexplained percentage by the gross battery capacity in a brochure. The reference value and definition would have to match. Without that explanation, the energy available for your journeys remains unknown.

A range figure also needs a clear basis. AVILOO, for example, describes calculations based on comparable vehicles or the car’s previous average consumption. (AVILOO) That does not mean your particular route has been measured. Ask which assumption underlies the distance figure before using it to plan your everyday driving.

Copy the table and fill it in alongside the full report. “Not stated” is a useful entry. Do not fill gaps with assumed values. The last column explains why you need each detail.

Not every method documents the same conditions. A missing temperature entry does not automatically make a report unusable. Ask which conditions matter for that method and how they were taken into account.

Do not set a blanket expiry period based on the date alone. If the report reflects a much earlier point in the car’s history, or battery work has taken place since, ask the testing company whether a new test would be useful for your purchase decision.

Back to the fictional listing with “90 percent”: the full report arrives. The vehicle details match, and the test date and mileage are present. But the reference for the percentage is still unclear.

In your worksheet, you can now write “matched” for the vehicle and “reference value unknown” for the result. You do not need to judge the battery negatively or accuse the seller of making a false promise.

A useful follow-up question is:

What does the 90 percent figure in this report refer to? Please show me the explanation of the test method and the new-condition value used as a reference. Does the report state a value for usable energy?

Only with that answer can you judge whether the report is useful for your comparison or whether you need different information.

Read the limitations below the result, too. AVILOO explicitly states that its diagnosis relies on the vehicle data provided. Mechanical damage for which no data is available through the diagnostic port is not covered. The result also describes the time of the test, not future changes. (AVILOO)

A note like this helps you specify the next examination: if you suspect damage to the battery casing, you need that component examined, not another interpretation of the same percentage.

Check battery ownership and completed recall work separately. Our guides to rented and owned batteries in the Zoe (German-language guide) and battery work on the Kona (German-language guide) explain the relevant documents in more detail.

When comparing inexpensive EVs, this worksheet complements our used EV comparison under €10,000 (German-language guide): this article helps you read the report; that guide helps you assess which cars to search for and their compromises.

If a listing you are considering says only “battery tested,” the free Vehilo First Look can help you make sense of the visible claim and identify useful questions for the seller.

The worksheet and example were created for Vehilo with AI assistance. They are based on the ADAC and AVILOO descriptions cited above, accessed on 17 October 2026. Vehilo did not examine a vehicle or an actual customer report for this article.