Used electric car: documents to check the battery and warranty
A guide to requesting, reading and cross-checking the documents that help reduce uncertainty about the traction battery of a used electric car in Spain.
Key points
A used EV battery cannot be assessed from mileage or the range shown on screen alone. Before leaving a deposit, cross-check its identity, history and recalls with the DGT, request the warranty terms that apply to its VIN and, where available, an SOH report with an identified date and method.
Assess the battery with evidence, not one figure
When comparing a used electric car, it is useful to separate three areas. The first is administrative: the vehicle’s identity, date of first registration, recorded mileage, ITV (Spanish vehicle inspection) history, owners, outstanding finance or charges, and possible recalls. The second is contractual: which battery warranty remains in force and under what conditions. The third is technical: a possible state of health, or SOH, provided there is an identifiable and comparable report.
None fully replaces the others. The full DGT report is useful for cross-checking much of the administrative history, including mileage, ITV records and outstanding recalls, but it does not include a traction-battery health value. Conversely, an SOH percentage does not prove that the warranty remains in force or that the documentation belongs exactly to that car.
The practical rule before paying a deposit is simple: request the documents in advance, check that the registration number and VIN match each other and the vehicle, and put any condition decisive to your purchase in writing. If the seller cannot document a fact, treat it as unverified, rather than as a promise that should be reflected in the price.
Section references: Informe de un vehículo ↗ · Real Decreto 920/2017, inspección técnica de vehículos ↗
- Verifiable through official sources: identity, first registration in Spain, ITV, recorded mileage and outstanding recalls.
- Verifiable through manufacturer or seller documents: specific warranty terms, available work carried out and invoices.
- Requires an identifiable technical report: an SOH figure or assessed capacity.
- Not conclusive on its own: dashboard mileage, age, displayed range or statements about charging habits.
Why age and mileage are not enough to know the battery’s condition
Age and mileage help describe the vehicle’s life, but they do not by themselves measure the battery’s remaining capacity or its ability to deliver the specified performance. The ITV history and mileage readings in the DGT report are valuable for checking the advertised odometer reading; they are not a measurement of battery condition.
It is also important not to confuse state of charge with state of health. Regulation (EU) 2023/1542 defines state of charge as the available energy expressed as a percentage of the declared nominal capacity. State of health, by contrast, refers to the battery’s overall condition and its ability to deliver the specified performance compared with its initial condition. Seeing 80% charge on the screen means the car is not full; it does not mean it retains 80% of its original capacity.
Therefore, do not reject or approve an EV solely because it has low or high mileage. Use those details to ask questions and check consistency with the rest of the file, not to calculate degradation that the available documents do not demonstrate.
Section references: Informe de un vehículo ↗ · Reglamento (UE) 2023/1542, relativo a las pilas y baterías y sus residuos ↗
- Compare the advertised mileage with the available history, but do not turn it into a battery-health percentage.
- Always distinguish between the current charge percentage and SOH.
- If the advert says “perfect battery” or “no degradation”, ask for documentary evidence and the date of that statement.
The file to request before seeing the car
Ask the seller for the vehicle technical inspection card (ficha técnica/ITV card) and, where available, the registration permit (permiso de circulación). These help identify the vehicle. ITV rules require the documentation to be checked against the registration number, VIN, make and model. The same match should appear on invoices, service history, any warranty documentation and any battery certificate given to you.
Also request the full DGT report, or the details needed to obtain it. It lets you check the date of first registration in Spain, ITV and mileage records, number of owners, outstanding charges and recalls still to be remedied. Review recalls before negotiating: an outstanding recall is not a battery measurement, but it is an administrative and maintenance issue that should be clarified.
Ask for the invoices and records of work that the seller retains, especially if they declare a repair, replacement or diagnosis related to the high-voltage system. Do not assume that the lack of invoices proves no work was carried out; it simply means you cannot verify it through that document. If a certificate of conformity is provided, it must be original and correspond to the complete or completed vehicle.
Section references: Informe de un vehículo ↗ · Real Decreto 920/2017, inspección técnica de vehículos ↗ · Manual de procedimiento de inspección de las estaciones ITV, versión 7.8 ↗
- Vehicle technical inspection card (ficha técnica/ITV card) and registration permit (permiso de circulación), if available.
- Full DGT report to cross-check administrative history and outstanding recalls.
- Warranty terms supplied with the vehicle and any extension or transfer communication, where available.
- Service history and retained invoices for diagnostics or repairs.
- Original certificate of conformity, only when it is used to identify original specifications.
What a health or SOH certificate should include
An SOH report can add useful information, but only if it makes clear what was measured and when. Keep the complete document and ask it to identify the issuer, date, type of test or method used, and result. European Regulation specifically requires these documentary elements in the context of tests on used batteries intended to prove that they are not waste; as a buying criterion, they are also the minimum needed to put a figure in context and ask reasonable questions.
Do not automatically treat two percentages from different providers as equivalent. Without a stated methodology and conditions, it is not known whether both results describe the same quantity or whether they are comparable. European rules require reliable, accurate and reproducible methods for conformity measurements and calculations, which reinforces the value of requesting an identified method before using an SOH figure to compare cars or negotiate the price.
Avoid two common mistakes: reading the charge level as battery health and treating an isolated percentage as a guarantee of future range. The report can be an important piece of evidence, but it must align with the VIN, its date and the rest of the history. If the seller offers only a screenshot without an issuer, date or method, request the original report or consider a professional inspection before buying a used car.
Section references: Reglamento (UE) 2023/1542, relativo a las pilas y baterías y sus residuos ↗
- Check that the report identifies the vehicle or VIN sufficiently.
- Note the issuer, date, method or test type, and result.
- Ask whether the result is stated as state of health, capacity or another parameter; do not assume they are equivalent.
- Do not compare percentages from different reports without knowing how they were obtained.
Battery warranty: check term, mileage, threshold and exclusions
The commercial battery warranty depends on the specific vehicle. A generic brand webpage or the advert is not enough: Tesla Spain, for example, expressly states that its web information is for information only and refers to the warranty supplied with the vehicle as the authoritative source. Request that document and check that it applies exactly to the version, market and VIN you are considering.
Review four points: start date, duration in years, mileage limit and capacity threshold, if one is included. Add any listed exclusions, maintenance or use requirements, and the claims procedure. As an example of why there is no common rule, Tesla publishes different mileage limits by version within its own range; therefore, applying the warranty from another trim to the advertised car is a buying mistake.
The manufacturer’s commercial warranty does not replace the statutory warranty on the sale. In a purchase from a professional seller, the statutory warranty for a second-hand item may be agreed for less than three years, but never for less than one year. Purchases between private individuals are not covered by that statutory warranty, according to information from the European Consumer Centre in Spain. Distinguish between both frameworks and ensure the contract clearly identifies the seller, vehicle and agreed terms.
Section references: Informe de un vehículo ↗ · Garantías ↗ · Garantía del vehículo ↗
- Do not calculate warranty only from the model year: check the first registration date and the applicable document.
- Confirm the mileage limit against the current reading and available history.
- Read whether there is a capacity threshold and what conditions the document sets for applying it.
- If buying from a professional seller, also review the statutory warranty on the sale; do not confuse it with the commercial battery warranty.
Displayed range: use it as context and complete the purchase with a checklist
The range figure shown on the dashboard may be useful to understand what that vehicle is displaying at that moment, but it does not prove degradation. Tesla explains that, when range is expressed in kilometres, its figure is based on an EPA certification test and that real range depends on speed, driving style, weather and terrain. Therefore, a single reading should not be converted into a direct comparison with the homologated range or that of another car.
A range loss claimed by the seller, persistent warnings, references to replacements or repairs, outstanding recalls, an SOH certificate without a method, or a complete lack of history do not by themselves prove a fault. They do justify pausing the deposit, requesting documented clarification and considering an independent inspection. The aim is not to demand impossible certainty, but to know what is proven, what remains unresolved and whether the price reflects that uncertainty.
Before signing, keep copies of the documents reviewed and state in the contract the elements that were decisive to your decision. To organise the rest of a used-car review, you can use this used car buying checklist.
| Document or data point | What it allows you to check | Main limitation | Who to request it from |
|---|---|---|---|
| Vehicle technical inspection card (ficha técnica/ITV card) and registration permit (permiso de circulación) | Identity: registration number, VIN, make and model | Does not measure battery capacity or SOH | Seller |
| Full DGT report | First registration, ITV, mileage, outstanding charges and recalls | Does not include traction-battery health | Buyer or registered keeper with the necessary details |
| Applicable battery warranty document | Term, maximum mileage, capacity threshold if any, and terms | A generic brand webpage does not confirm coverage for that unit | Seller and manufacturer, where appropriate |
| Available history and invoices | Documented work carried out or diagnostics | The absence of documents does not prove no work took place | Seller |
| Identifiable SOH report | Technical result with issuer, date and method or test type | It cannot be compared with another report if the method and conditions are unknown | Seller or the provider that issued it |
| Range displayed on screen | Reading shown by the vehicle at that moment | Does not prove degradation or future real-world range | Vehicle during the viewing |
Section references: Informe de un vehículo ↗ · Consejos de autonomía ↗
- Check that the registration number, VIN, make and model match on the car and in the documentation.
- Compare the advert with the DGT report: first registration, ITV, mileage and outstanding recalls.
- Request the applicable warranty document and review its term, mileage limit, threshold and exclusions.
- If there is an SOH result, retain the complete report with issuer, date, method and result.
- Do not complete the purchase based only on dashboard range or a charge percentage.
- If there are contradictions or no evidence, request clarification or an independent inspection before leaving a deposit.
Does the DGT report state the battery health of an electric car?
No. The full report provides details such as ITV history, mileage, owners, outstanding charges, technical data and pending recalls, but it does not include a traction-battery health value.
Does 80% on the screen mean the battery has degraded by 20%?
No. That percentage may be the state of charge, meaning the energy available relative to the declared nominal capacity. SOH is a different concept and refers to the battery’s overall condition compared with its initial state.
Can I trust any SOH certificate?
Request the complete document and check the issuer, date, method or type of test, and result. A percentage without those details does not make it clear what was assessed or allow reliable comparison with another report.
Can the battery warranty be checked only on the brand’s website?
That is not advisable. General information can be useful guidance, but you should review the warranty supplied with the specific vehicle, together with its version, first registration date, mileage and applicable terms.
Does the range shown on the dashboard prove the battery’s condition?
Not by itself. Range in kilometres may be based on a certification figure, and real range depends on factors such as speed, driving, weather and terrain.
