The kilometers do not fully reflect the battery condition
The kilometers on the meter is still an important data when evaluating used cars. However, this number cannot fully reflect the level of battery degradation.
A large-scale study in the UK, based on more than 8,000 electric vehicles of 36 brands, recorded an average battery health status of 95.15%. For the group of vehicles that have been used for 8-9 years, the neutral battery capacity is still around 85%. This result shows that the level of battery degradation varies between vehicles and cannot be assessed solely based on vehicle age or kilometers.
Factors such as operating conditions and usage processes can also affect the level of battery capacity reduction. Therefore, two cars with the same year of manufacture and kilometers may not have the same battery condition.
For buyers of used electric vehicles, actual battery inspection therefore becomes an additional content besides exterior, interior, operating system and maintenance history inspection.
Reduced battery does not mean the car has to replace batteries
The reduced battery capacity over time does not mean that an old electric vehicle will quickly have to replace the entire battery pack.
Data from a study on more than 8,000 electric vehicles shows that most vehicles still maintain significant capacity after many years of use. The 8-9 year old car group in the study still has a neutral capacity of about 85%.
This shows that old electric vehicles should not be defaulted to a seriously degraded battery pack. The actual condition needs to be assessed based on the data of each vehicle.
A more noteworthy issue lies in the ability to access information. If the buyer only knows how many kilometers the car has traveled but does not have data on the battery condition, it will be difficult to fully assess the actual value of the car.
China standardizes battery durability assessment
This issue is being included in specific technical standards.
On December 31, 2025, China announced the GB/T 46991.1-2025 national recommendation standard on the requirements and methods of testing the durability of power batteries on electric vehicles, part applicable to light vehicles. According to the China Automobile Standards Research Institute (CATARC), the standard is built to unify the method of assessing battery durability at the vehicle-wide level, thereby providing a basis for assessing the capacity reduction process in actual usage conditions.
This standard takes effect from July 1, 2026. One of the notable contents is the requirement to monitor the energy availability status of the battery (SOCE) and the energy availability distance status (SOCR) during the vehicle life cycle. In which, SOCE reflects the amount of energy that the battery can still provide, while SOCR reflects the distance the vehicle can travel corresponding to the amount of energy availability.
The latest SOCE information must have at least one method for users to access. The standard also stipulates that the difference between the SOCE value provided by the vehicle and the actual measurement result does not exceed 5%, in order to improve the accuracy of data on the energy availability of the battery.
Putting health and battery life data into a unified evaluation method shows that information about battery packs is increasingly important in the process of using and trading used electric vehicles.
For buyers of used electric vehicles, kilometers and maintenance history are still necessary information, but not enough to comprehensively assess a vehicle. Data on battery status will help buyers have more basis to determine the remaining usable value of the vehicle.
What should used electric vehicle buyers check?
When buying used electric vehicles, consumers should check the battery life, maintenance history, repair, recall and software updates of the vehicle. If possible, sellers should be required to provide data on battery health and check the estimated distance after full charge, and note that the results also depend on weather conditions, driving habits and the use of air conditioning. Buyers also need to check the battery life, battery warranty conditions and the possibility of warranty transfer when the vehicle changes ownership. Before the transaction, taking the vehicle to a specialized facility for overall inspection, especially the battery life, will help have more basis to assess the actual condition of the vehicle.
