An 82% retention floor after five years appears fairly generous to automakers, but it sets a baseline for compliance. By Stewart Burnett
China has disclosed the implementation details of a new national standard, GB/T 46991.1-2025, that sets accuracy requirements for how electric vehicles (EVs) display battery health, and defines minimum capacity-retention thresholds by age and mileage. Developed by the Ministry of Industry and Information Technology (MIIT) and the Standardisation Administration of China (SAC), the standard is now being enforced after being published last year.
The core metric is State of Available Energy (SOCE), a term which denotes a ratio of a battery’s current maximum usable energy against its original factory capacity. This is distinct from the everyday State of Charge reading that shows how full a battery is at any given moment. Under the new rules, the deviation between a car’s displayed SOCE and value when physically examined cannot exceed 5%.
Another new requirement concerns something called “virtual mileage”. Under the rule, energy consumed while a vehicle is parked, for climate control or other auxiliary systems, must be converted into an equivalent driving distance, with the displayed figure—the virtual milage—required to stay within 3% of the measured result.
On durability, vehicles must retain an absolute minimum of 82% of their original available energy after five years or 100,000km, falling to 75% after eight years or 160,000km, and 70% after ten years or 200,000km. Some industry observers have already questioned whether an 18-percentage-point allowance after five years is an unusually generous concession to automakers, although others note it functions as a floor rather than a target, and many packs already substantially outperform it in practice.
It should be noted that the new rules are recommended GB/T standards, rather than mandatory GB ones, meaning compliance is technically voluntary and carries no disclosed penalties or recall obligations. While this also may appear quite lenient, MIIT-backed recommendations of this kind have nonetheless tended to become de facto industry requirements in China, since manufacturers that ignore them risk reduced access to state subsidies, fleet procurement contracts, and consumer trust.
The commercial consequences of the new rules point squarely at the used EV market. By giving buyers, warranty providers and residual-value assessors a standardised reference for battery degradation, the metric could potentially reshape how second-hand EVs are priced and how disputes over battery health get resolved, addressing a persistent industry problem where dashboard readings and actual usable capacity have often diverged.
Setting the five-year retention floor at 82%—comfortably below what many current battery chemistries already achieve—suggests that China designed the standard as a baseline consumer protection against underperforming packs, rather than a technical benchmark meant to push manufacturers toward better degradation performance. Its real function, then, is standardising the conversation around battery health, not necessarily raising the bar on it.