Buying a Used EV - How to Check Battery Health

As the used electric car market grows, one question comes up more than any other: how healthy is the battery? It’s a sensible concern, because the battery is the most valuable part of an electric vehicle. The reassuring news is that checking battery condition is becoming easier, and many dealers are now starting to provide this information upfront.

Unlike a petrol or diesel engine, EV batteries don’t suddenly fail. Instead, they slowly lose capacity over time, meaning the car’s range reduces slightly as the years go by. Most manufacturers warranty their batteries for around eight years or 100,000 miles, usually guaranteeing at least 70% of the original capacity. In reality, many cars perform better than this, but it still makes sense to understand what you are buying.

Battery health is normally measured as a percentage, often called State of Health (SoH). A reading of 90% means the battery can hold 90% of the energy it could when new. For example, a car that originally had a 250-mile range might now achieve around 225 miles. For most drivers, that difference is relatively small in day-to-day use.

The good news is that dealers are increasingly recognising that buyers want reassurance. Some specialist EV dealers now provide battery health certificates as part of the sales process, using diagnostic tools to read data directly from the vehicle. This is similar in principle to a service history for a petrol car and can give buyers much more confidence.

Independent inspections are also becoming more available. There are companies that will test an EV battery and provide a report, either through a physical inspection or by using a plug-in diagnostic device connected to the car. As the market matures, this type of service is likely to become more common and more affordable.

It’s also worth remembering that battery health is only part of the picture. How the car has been used matters too. Regular rapid charging, very high mileage, or long periods sitting unused can affect degradation, while steady everyday driving and home charging tend to be gentler on the battery.

For buyers, the key takeaway is that a used EV battery should not be a mystery. Ask the dealer if they can provide a health report, check whether any manufacturer warranty remains, and compare the current range with the original specification. In many cases you’ll find the battery is in better condition than expected.

As confidence grows and more data becomes available, battery health checks are likely to become a normal part of buying a used electric car. That can only be good news for buyers looking for reassurance and good value.

If you have anything you want me to cover or have any EV questions please email in to events@nottinghamevs.co.uk