A new study of the second-hand electric vehicle market has found that Kia and Tesla produce the most durable batteries, with the majority of used EVs maintaining high energy capacity even after years of use, according to a report by the Sweden Herald.

The investigation, conducted by Swedish used-car broker Kvdbil, analysed battery health data from 1,300 electric vehicles and plug-in hybrids. Researchers evaluated each vehicle’s battery using a “State of Health” (SoH) rating, which compares a battery’s current performance against its original capacity.

The findings were striking: eight in ten vehicles tested received the top grade, indicating that their batteries still retain more than 90 per cent of their initial capacity.

Kia’s EV6 and e-Niro, along with the Tesla Model Y, topped the rankings for battery performance, followed by models such as the Opel Mokka-e, Mazda MX-30, Audi Q4 e-tron, and Volkswagen ID.4.

Kvdbil’s test manager Martin Reinholdsson said the results suggest modern EV batteries are proving more resilient than many had expected.

“They are actually better than we thought,” Reinholdsson told the Sweden Herald. “It’s not so much tied to a specific brand or model, but rather how the cars have been used and maintained.”

The vehicles showing lower battery performance were generally older models with higher mileage, reinforcing the idea that age, climate, and charging habits are the main factors influencing battery wear.

Reinholdsson noted that drivers can extend battery life through proper charging and storage practices. Avoiding frequent fast charging, limiting regular charging to around 80 per cent, and keeping vehicles away from extreme heat or cold were among the recommended measures.

“These are the things owners can control,” he added. “Age and distance travelled, of course, are much harder to influence.”

Kvdbil’s analysis covered 723 fully electric cars and 643 plug-in hybrids. Overall, the results indicate that fears about rapid battery degradation in used EVs may be overstated – a positive signal for both consumers and the growing second-hand EV market.