Thinking of buying a used electric car or plug-in hybrid? Before you go any further, there is one thing you should always do: check the condition of the battery. It is the heart of the vehicle, and also its most expensive part.
SOH certificate: check the battery of your next electric car
Good news for your purchase: since 2026, the Car-Pass can include the battery's state of health (SOH). This is a simple percentage, measured by an independent tester. The figure appears directly on the legal document the seller hands over, together with a full test report. So you know exactly what you are buying.
Has the seller given you their Car-Pass?
Check its authenticity online and go straight to the SOH and the test report.
What the SOH certificate shows you on the Car-Pass
If the seller has had the battery diagnosed, the Car-Pass shows two key elements:
- the SOH value in %: it compares the battery's remaining capacity with its original capacity;
- the full test report: on the digital Car-Pass, you click on the result and go straight to the report drawn up by the tester.
All this data comes on top of the usual information: odometer history, maintenance history, Euro standard, CO2 emissions, open recalls or any post-accident inspection still to be carried out. The result? You can assess the health of the battery and the car's entire history on a single document.
Why insist on an SOH before buying a used electric car
"For electric vehicles, the condition of the battery is at least as important as the mileage," says Michel Peelman, managing director of Car-Pass.
With a certified SOH, you take control of your purchase:
You know the real wear: the percentage tells you how worn the battery really is, something that age and mileage alone cannot tell you.
You check the warranty: many manufacturers guarantee the battery up to a certain SOH threshold (for example 70%). So you know where the battery stands in relation to that threshold.
You negotiate a fair price: the battery accounts for a large share of the car's value. If its capacity has dropped, you have a concrete argument to bring the price down.
You avoid nasty surprises: replacing or repairing a worn-out battery can cost several thousand euros. Better to know before you sign.
How to check the battery of the car you want to buy
1. Ask the seller for a Car-Pass that includes the SOH
Every seller, whether a private individual or a professional, is legally required to give you a Car-Pass that is less than two months old. From your very first contact, ask them whether the battery's state of health is already on it.
2. Suggest a test if the SOH is not shown
The seller has two options:
Test with a tester linked to Car-Pass: Car-Pass retrieves the report. The seller links it to their vehicle using the chassis number.
Test with another tester or with the manufacturer: the seller enters the SOH value himselve.
In both cases, the report must be less than 6 months old and showing the vehicle identification number and the mileage.
Curious to know how a battery's SOH is measured? There are several methods, and the full report can always be viewed on the digital Car-Pass.
3. Scan the Car-Pass QR code
The QR code gives you access to the digital Car-Pass. There, you can check if the document is authentic and view the full battery test report.
4. Cross-check the SOH with the rest of the Car-Pass
Consistent mileage, an up-to-date maintenance history and no open recalls: combined with a good SOH score? These indicators allow you make an offer with complete peace of mind.
Still preparing to buy your car? Have a look at our checklist for buying a used car.
Is there still an open recall on this vehicle?
Car-Pass has a direct connection with almost all manufacturers. Simply enter the vehicle identification number to find out.
Check open recalls
A reliable SOH, from measurement to document
An independent test
The measurement is carried out by an external tester, independent of the seller.
Direct transmission
The report is either retrieved directly by Car-Pass or entered by the seller.
A report you can view
You can consult the full analysis report yourself from the digital Car-Pass.
A protected document
Every Car-Pass includes a unique identification number and a QR code.
An official framework
The non-profit organisation Car-Pass carries out a public-interest mission governed by the law of 11 June 2004. The addition of the SOH is based on a letter of intent from the Ministers for Consumer Protection and Mobility, pending a European framework.
Selling an electric car?
Reassure your buyers by showing your battery's state of health directly on the Car-Pass. All you need to do is have the vehicle tested by an independent tester, then link the analysis report to your car before requesting your Car-Pass. The SOH score will then appear automatically on the document.
Link your SOH report to your Car-Pass
Simply have your vehicle's chassis number and the name of your tester to hand.
Frequently asked questions about the SOH certificate
How can I find out the SOH of a used electric car before buying it?
Ask the seller for the vehicle's Car-Pass and check whether the battery's state of health is shown on it. If it is, scan the QR code to view the digital Car-Pass and the full test report. If the SOH is not shown, you can ask the seller to have the battery tested by a recognised tester before the Car-Pass is issued.
Is the seller required to provide the SOH?
No, including the SOH on the Car-Pass is optional. The Car-Pass itself, however, is mandatory: the seller must give it to you at the time of sale. If they fail to do so, you are entitled to have the sale cancelled and your money refunded. For an electric car, nothing stops you from making the SOH a condition of your purchase.
The Car-Pass does not show an SOH. What can I do?
Suggest that the seller has the battery tested by an independent tester, then links the report to their vehicle on the Car-Pass website. The SOH only appears on a Car-Pass issued after the report has been linked. If the Car-Pass has already been issued, the seller can get a new one at the counter of a vehicle inspection centre, without having to undergo an inspection, by bringing the vehicle along.
How do I view the full test report?
Scan the QR code on the Car-Pass to access its digital version. Then click on the SOH value: the report drawn up by the tester opens directly. This way, you check the result yourself, without having to rely on the seller's explanations.
Which vehicles does this apply to?
Fully electric cars and plug-in hybrids. For both types of vehicle, the battery has a major impact on the car's value and on everyday use. That makes it the first thing to check before you buy.
How long is a Car-Pass valid?
The Car-Pass handed over at the time of sale must not be older than two months. Check the date on the document: a recent Car-Pass ensures you have up-to-date information on the vehicle.