Battery health remains one of the biggest unknowns in used EV and PHEV transactions, shaping both buyer confidence and residual values.
For Alexander Millinger, senior sales manager at AVILOO, the issue is straightforward: clarity builds trust, but only if the data goes far enough. “Battery diagnostics bring clarity, confidence and trust,” he says. “It’s important that the battery is properly diagnosed, not just read out.”
Why SoH alone is not enough
That distinction is becoming more important as the market matures. Many retailers still rely on a simple State of Health (SoH) figure pulled from the vehicle’s battery management system, but Millinger argues that this alone is insufficient.
“A readout only shows a calculated value. It doesn’t tell you if there are defects or damage within the cells,” he explains. “Without a full diagnostic, you are missing critical information.”
Independent testing goes deeper, analysing cell level performance, charging behaviour and usage patterns, with results benchmarked against wider datasets.
The difference can be material. In one case, a vehicle showing 100% SoH via OEM data was found to have significant underlying cell defects when independently tested.
In another, a dealer faced a full refund after a post sale battery issue emerged. “That is complete financial damage for the retailer,” Millinger says. “Diagnostics are about protecting the dealer as much as informing the customer.”
Diagnostics drive speed and margin
The commercial upside is also becoming clearer. Dealers using certified battery reports are seeing faster stock turn and improved margins.
“We’re seeing cars sell 20 to 30% faster, often at higher margins,” he says. “If you’re not using diagnostics, you’re behind the market.”
Just as importantly, certification is changing how EVs are presented. Rather than a risk to be managed, the battery becomes a verified asset.
“You’re not just selling the car, you’re showing the battery value, whether it’s at 90% or 100%,” he says.
With customer demand rising, Millinger expects independent battery certification to become a standard requirement, much like service history or mileage checks, within the next two
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