Buying a secondhand EV? Questions you should ask about the battery

“With petrol or diesel cars, buyers base a judgement about engine condition on age and mileage. But EVs are not like this. The most important element is the battery, and its condition can vary significantly based on several factors - even if two cars have identical mileage and age,” says Kevin Mackay, Director of Volta Automotive.

Volta Automotive is a local business specialising in testing the State of Health (SoH) of EV and Plug-in Hybrid Electric Vehicle batteries. “The health and longevity of a battery are affected by factors such as the number of fast charges, whether the battery has been left on charge for long periods of time, temperature, day to day management of the battery, and repeated extreme charging and discharging,” Kevin explains.

As a buyer of a secondhand EV or PHEV, there is no way you can tell how the battery has been treated, and consequently it’s difficult to judge how much life you can expect to get from it - and what its true value is.

That’s where Volta Automotive comes in. They provide a professional Battery State of Health assessment, which is a measure of the battery’s current performance compared to its original condition.

The chart below illustrates how one car might have covered 124,300 miles with a battery health of over 90%, while another with the same mileage might have a battery health as low as 65%. A sample of cars manufactured in 2023 found that battery degradation was approximately 1.4% per year on average. This means one of these cars could have an additional 17 years of battery life compared to the other. Purchasing the one with the lower battery health would make a costly battery replacement necessary for continued viability – and this would need to be reflected in the sale price.

As a buyer of a secondhand EV or PHEV, there is no way you can tell how the battery has been treated, and consequently it’s difficult to judge how much life you can expect to get from it - and what its true value is.

“The benefit of the tests I provide is the independent verification for buyer confidence and assurance,” says Kevin. “Overlooking the battery State of Health when purchasing a used EV could be a very expensive mistake.”

If you already own an EV or PHEV, it’s worth getting a battery SofH assessment done to check on the range capacity, detect any hidden defects, predict battery replacement and to discover ways you can maximise your battery’s lifespan. When it comes to selling your car, a battery certification can also lead to a higher sale price and faster sale.

For more information on tests available, contact Kevin at Volta Automotive on 07701 260 120

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Published in Konect March 2026

Author: Volta Automotive