A £15 Bluetooth OBD2 dongle and a free app sounds like an easy way to check an EV battery before you buy. It sort of works. But there is a critical limitation most people do not realise — and it matters enormously when there are thousands of pounds on the line.
OBD2 (On-Board Diagnostics) is a standardised port fitted to every car sold in Europe after 2001. When you plug in a Bluetooth dongle and connect an app, you are asking the car own computers what they know. For EVs, that includes battery temperature, state of charge, estimated capacity, and fault codes.
The problem: all of this data comes from the car own Battery Management System. The BMS is telling you what it thinks — or what it has been calibrated to report.
Individual battery cells degrade unevenly. A pack with weaker cells may still show a reasonable SOH because the BMS is managing around them. OBD tools see the BMS output, not the underlying cell behaviour.
A screenshot from an OBD app has zero chain of custody. It carries no legal weight for warranty claims or insurance assessments. An Aviloo certificate has a unique test ID, timestamp, VIN, and TUV certification.
PAD is South Wales only Aviloo-certified mobile EV battery testing service. Independent cell-level analysis. Official TUV-certified certificate. We come to your address.
