Alexander Millinger, Senior Sales Manager UK at BVRLA associate member AVILOO, explores the difference between reading an electric vehicle’s battery data and conducting an independent diagnostic test, and why that distinction matters for vehicle valuations, residual value risk and confidence in the growing used EV market.
For rental, leasing and fleet operators, understanding the true condition of an EV battery is becoming increasingly important when valuing vehicles, managing residual value risk and giving customers confidence in used EVs.
We keep running into the same claim: "Don't worry, this is independent, we're just reading the data from the car." That sounds reassuring at first, but it's often misleading. Many providers use the word "independent" rather loosely, when in reality they're simply reading out the data the manufacturer itself supplies and passing it on. At AVILOO, we offer a genuinely independent EV battery quick test, because repeating a figure the car already claims about itself isn't independence, it's self-reporting.
This means the battery isn't checked cell by cell. Instead, it produces an average across the entire battery pack, based on assumptions the manufacturer makes and rarely explains in any detail. Think of it as a choir of 96 singers: if one voice is out of tune, the average can still sound fine, because the rest of the choir compensates. In the same way, a single weak cell can hide within a battery pack while the dashboard keeps insisting everything is fine. Yet that weak cell is exactly the one worth a closer look.
The AVILOO FLASH Test checks every voice individually. It takes real measurements at cell level, not an average. From these, it calculates the State of Health, a measure of how much capacity a battery still has. It uses a model built on a large, verified database, not on the vehicle's own assumptions. This makes it possible to spot a single weak cell even within a pack of thousands. The result is reproducible and, crucially, independent, so a third party can stand behind it.
With the used EV market growing and battery health increasingly shaping residual values, this distinction matters more than ever, particularly at lease return and remarketing, where confidence in a vehicle's condition directly affects its value. Many in the industry aren't yet fully aware of this distinction. Until recently, "battery condition" was little more than a vague notion. That's changing fast, and we think this is how our industry should develop.
Since July this year, an independent diagnostic result in the UK can be backed by a financially secured AVILOO Battery Warranty. If a battery's condition drops below an agreed threshold within one year or 20,000 km, the owner is compensated financially. A warranty like this cannot be built on an unverified, self-reported figure. Few insurers would be willing to underwrite self-reported data without independent verification behind it. They will only stand behind a figure that has been independently verified at cell level and checked against a large, reliable dataset.
That, in our view, is the practical answer to "why does this matter". A read-out is a claim. A diagnostic test is proof. And proof is what allows a rental, leasing or fleet company to make a financial promise without carrying the entire risk itself.
If we could offer one piece of advice to anyone in our industry assessing battery condition claims, whether at fleet handover, lease return or the sale of a used EV, it would be this: ask where the figure comes from. Was it estimated or measured? Would an independent party put their name, or their money, behind it?
We work in EV battery diagnostics every day, so we'll admit to a professional bias here. But we'd make the same argument without it, because the fleet industry doesn't just need battery data. It needs battery data it can actually rely on.
As the used EV market continues to mature, trusted and transparent battery diagnostics will play an increasingly important role in building confidence for fleets, retailers and consumers alike.
