The Battery Health Certificate
Issued by AVILOO: A Global Leader in Battery Diagnostics
Every certificate is issued directly by AVILOO using their TÜV Certified testing methodology. Battery Health Check is an authorised AVILOO partner: we provide the service, AVILOO provides the science. Certificates cannot be edited or modified by anyone, including us. That independence is exactly what makes them trustworthy, and it is the reason to insist on an independent test rather than a dealer's own word.
What the Certificate Includes
AVILOO's battery health certificate is a comprehensive, independently verified document that gives buyers complete confidence in the vehicle's battery condition. Each certificate contains:
- State of Health (SoH): independently calculated percentage, not from the vehicle's BMS
- Cell-level heatmap: visual map showing the condition of each individual cell, with colour-coded severity indicators
- Real-world range: three range metrics: WLTP range, peer-comparison range, and individual range estimate
- Benchmarking: how this battery compares to vehicles of the same make, model, age, and mileage
- QR code: for instant digital verification of certificate authenticity
- AVILOO CERTIFIED seal: awarded when no defects or anomalies are detected
Reading Your Certificate, Field by Field
If you are buying the car, this is the part that matters. Here is what each figure on the page actually means in plain language.
State of Health (SoH)
State of Health is the single most important number on the certificate. It is the battery's usable capacity today expressed as a percentage of its capacity when new. A brand-new pack is 100%. Batteries lose a little capacity over time and mileage, so a used EV will read below 100%, and that is completely normal.
A strong result sits in the 90s. The closer to 100%, the less range the battery has lost and the more life is left in it. As the number falls, so does the distance you can drive on a full charge. What counts as a good figure depends on the car's age and mileage, which is why the certificate does not show the percentage in isolation: it also shows you how this exact battery compares with others like it (see Benchmarking below). A car with a slightly lower SoH than average for its age is a fair reason to negotiate on price. Crucially, this percentage is calculated independently by AVILOO and is not simply read from the car's own dashboard, which can be optimistic.
Cell-Level Heatmap
An EV battery is not one block. It is hundreds or thousands of individual cells working together, and the pack can only ever be as strong as its weakest group of cells. The heatmap shows every cell as a coloured square so you can see whether the pack is ageing evenly or has a problem hiding inside it.
- Green cells are healthy and performing in line with the rest of the pack.
- Amber or yellow cells are beginning to lag behind their neighbours and are worth noting.
- Red cells are significantly weaker and are the ones that can drag down the whole pack.
Why does one weak patch matter when the rest looks fine? Because the battery management system protects the weakest cells, so a single underperforming group can quietly cap how much of the battery you can actually use and how quickly it charges. A car with a healthy overall SoH but a cluster of red cells deserves a closer look and a frank conversation with the seller. An evenly green map is exactly what you want to see.
The Three Range Figures
Range is shown three ways so you are not relying on a single optimistic sticker figure:
- WLTP range is the official lab figure the car was rated at when new. It is the marketing number, measured under ideal conditions, and it does not account for how this specific battery has aged.
- Peer-comparison range is what cars of the same make, model, age and mileage are typically achieving now. This tells you what is realistic for a car like this one in the real world.
- Individual range estimate is AVILOO's estimate for this exact battery, based on its measured condition. This is the figure most relevant to you, because it reflects the pack you are actually buying rather than an average.
Reading all three together tells you not just how far the car should go, but whether this particular example is keeping up with its peers or falling behind. For a fuller walkthrough of how battery condition drives range, see our guide to EV battery health.
Benchmarking and the AVILOO CERTIFIED Seal
Benchmarking places this battery against vehicles of the same make, model, age and mileage, so a percentage stops being abstract and becomes a ranking: is this a better or worse example than others out there? The AVILOO CERTIFIED seal appears only when the test finds no defects or anomalies. Its presence is a clean bill of health at the time of testing; its absence is a prompt to ask why.
How to Check a Certificate Is Genuine
A certificate is only reassuring if you know it is real. Every AVILOO certificate carries a QR code for exactly this reason.
- Scan the QR code on the certificate with your phone camera.
- It opens AVILOO's own verification page, hosted by AVILOO rather than the dealer.
- Confirm that the details shown online, above all the vehicle's VIN and the State of Health, match the printed or on-screen certificate in front of you.
Because the record is held by AVILOO and cannot be edited by the dealer or by us, a matching online record is your proof that the figures are authentic and unaltered. If a "certificate" has no QR code, or the code does not resolve to AVILOO, treat it with caution.
Important Note
The certificate reports the battery's condition at the time of testing. It is not a forecast of future performance, nor is it a mechanical or electrical safety inspection. It provides an accurate, independently verified snapshot of battery health at the point of sale.
Why It Matters
88% of used EV buyers want an independent battery health assessment before purchase (Startline Motor Finance Used Car Tracker, Aug 2025). An AVILOO certificate, produced with TÜV Certified methodology, gives them exactly that.
Because certificates are issued directly by AVILOO and cannot be altered, buyers know the results are genuine. No dealer can inflate the numbers. No middleman can adjust the findings. That is the trust your customers are looking for.
The battery is the most expensive component in the car and the hardest to judge by eye. Getting it wrong is costly on both sides: the average motor finance dispute reached £6,193 in Q4 2025 (Motor Ombudsman). A certificate turns a leap of faith into a documented fact for £100 as a private buyer, or £35 per test at dealer volumes.
Legal Protection
The certificate serves as auditable evidence of battery condition at point of sale. Under the Consumer Rights Act 2015, dealers face a reversed burden of proof in the first six months (s.19(14)): meaning defects are presumed to have been present at delivery unless proven otherwise.
A pre-sale AVILOO battery health certificate provides that evidence, and it protects the buyer just as much as the seller: it fixes in writing what the battery's condition was on the day you bought the car.
Trust Impact
- Certified vehicles command £450–£900 more than uncertified equivalents (AVILOO Remarketing Whitepaper, May 2025). See the full dealer sales impact data
- Certified vehicles sell faster: buyers do not need to negotiate down for battery uncertainty
A £2,700 battery warranty now comes with every qualifying certified car. Every qualifying FLASH test includes the AVILOO Battery Warranty at no extra cost to you or the buyer. If the battery later falls below its individually calculated threshold, the owner receives a £2,700 AVILOO-backed payout. Cover runs for 12 months or 12,400 additional miles, whichever comes first, is tied to the VIN, and transfers to the next owner. Claims go directly to AVILOO, and the cover complements, rather than replaces, the manufacturer warranty.
What to Ask the Seller For
If you are viewing a used EV, this is the short list that protects you:
- Ask for an independent battery health certificate, not the reading from the car's dashboard. Find out why the independence matters.
- Scan the QR code and confirm the VIN and State of Health match the car and the paperwork.
- Look at the heatmap, not just the headline percentage. An evenly green pack is the goal; a cluster of red cells is a question to raise.
- Check the certificate is recent. It is a snapshot, so the closer to your purchase date, the more it reflects the battery you are driving away.
- If there is no certificate, ask for one before you commit. A test takes about three minutes, and you can book one yourself for peace of mind.
Sources: Startline Motor Finance Used Car Tracker (Aug 2025); Motor Ombudsman (Q4 2025); AVILOO Remarketing Whitepaper (May 2025).