EV battery myth debunked in new study
By Tom White · 22 Jul 2026
A new report has shed light on which electric vehicles (EVs) maintain the highest percentage of battery life over time.Swedish car marketplace Carla has published results from a study into battery life of electric cars, using data from 10,000 battery tests on EVs in Sweden between 2022 and 2026.The results may come as a surprise to some, with the best brand for battery health after 10,000km travelled being Kia, and the second best being Hyundai with 96.8 per cent and 95.4 per cent battery health, respectively.The next brands down were premium marques Mercedes-Benz (95 per cent) and BMW (94.5 per cent), with Ford (94.3 per cent) sitting above Geely Group brands Volvo (94.2 per cent) and Polestar (93.7 per cent).Volkswagen Group vehicles took up the next four positions, which in order included Audi (92.9 per cent), Skoda (92.6 per cent), VW (92.4 per cent) and Porsche (90.9 per cent).Tesla, which is often quoted as a brand with impressive battery degradation figures in other studies placed 12th in the Swedish study, with its cars maintaining 90.2 per cent battery health after 10,000km.The grouping of various brands together comes as little surprise given each parent company will source batteries from similar places and use familiar chemistries and heat management methods.Another graph from the same study shows average battery degradation between the first 50,000km (94.39 per cent) and the next 50,000km was negligible, at just over 2 per cent. Average battery health of the 10,000 cars tested by 100,000km was 92.35 per cent.More interesting is the breakdown by model, with the study showing the car with the least overall battery degradation was the Kia Niro EV, which maintained 97.25 per cent of its battery capacity.The Hyundai Kona Electric and Kia EV6 also scored well, with the next model down being the Volvo XC40 Recharge and Polestar 2.The popular Tesla Model Y also maintained 92.18 per cent of its battery capacity on average over 10,000km, although ranked 18th in the study, below many VW Group, BMW, and Geely Group products.It is worth noting that this study does not simply transfer across to the Australian market. Many of the EVs delivered to Sweden are built in Europe which often use different battery suppliers to the versions of the cars sold here.In addition, Sweden’s cool climate may produce different results to our hot climate, with different demands placed on temperature management systems, and different pressures placed on batteries while discharging or charging.However, more Australian cars using batteries from Chinese suppliers may actually be an advantage. Lithium-iron phosphate (LFP) batteries from CATL (China’s largest battery supplier) are now pervasive across EVs from many brands sold in Australia. The Swedish study compared the performance of these Chinese CATL LFP batteries, Korean LG Chem batteries and two different types of Japanese Panasonic batteries, all in the Tesla Model 3 to control for model differences.The CATL cells had the highest average battery health, maintaining 93.3 per cent, the LG Chem cells were next at 91.5 per cent, and the Panasonic NMC batteries ranked lower at 89.8 and 88.2 per cent respectively.One factor worth keeping in mind is BYD’s lack of a major footprint in Sweden despite launching there in 2022, leaving it off the study. Not only does this exclude BYD from the ranking system, but it also leaves its batteries out.BYD sells its signature LFP ‘Blade’ batteries to many brands for cars sold in Australia, including Kia, KGM, and even entry-level versions of the Tesla Model 3 and Model Y.The study confirms several things - battery degradation is often over-stated, with almost all cars maintaining over 90 per cent capacity at the 100,000km mark, and newer chemistries and temperature management systems are having a notable improvement on battery life across all makes and models.Previous stories of cars losing up to 50 per cent of their capacity were often limited to early-generation NMC batteries using air-cooled technology. Almost all new EVs sold, particularly in Australia, use liquid-cooled cells.In other good news for Aussie EV owners and those considering a second hand EV, the Carla study is not the first time EV batteries have performed better than expected when surveyed en-masse.In Australia, auction house Pickles recently shared data based on its battery health scoring which showed EVs with between 80- and 120,000km were maintaining a battery health score of around 91 per cent.