GB/T 46991.1-2025, Requirements and test methods for in-vehicle traction battery durability of electric vehicles — Part 1: Light-duty vehicles, is a Chinese national standard governing how electric vehicles must measure and display traction battery health to the driver. It was published on 31 December 2025 and entered into force on 1 July 2026.
Disclaimer: This is not a definitive guide, just an indication, and it is important that you always go back to the source for legislation.
Purpose and Scope
GB/T 46991.1-2025 was led by China’s Ministry of Industry and Information Technology (MIIT) together with the Standardization Administration of China (SAC). Unlike GB 38031-2025, which governs crash and thermal-runaway safety, this standard addresses a different problem: whether the battery health figure shown on a car’s dashboard can be trusted. It applies to light-duty passenger electric vehicles, and is the first part of what is expected to be a multi-part series covering other vehicle categories.
It carries the “GB/T” (tuijian, recommended) prefix rather than the mandatory “GB” prefix, so compliance is voluntary. In practice, though, a durability and health-reporting figure is increasingly something buyers of used EVs check before purchase, so the standard is likely to become a reference point that resale platforms, warranty programmes, and regulators lean on even without a mandatory compliance requirement.
State of Available Energy (SOCE)
The standard introduces a defined metric called State of Available Energy (SOCE) — the usable energy the battery can currently deliver, as distinct from its original rated capacity. Under GB/T 46991.1-2025, the SOCE value displayed to the driver must not differ from the physically measured value by more than 5%. This is a meaningful constraint for BMS teams: state-of-health estimation algorithms that drift outside that error band at any point in the vehicle’s service life would not meet the standard’s requirement, which pushes the underlying SOH/SOCE estimation logic toward tighter calibration and more frequent capacity-learning cycles than many existing BMS implementations use today.
Durability Threshold
GB/T 46991.1-2025 sets a quantitative retention benchmark for light-duty passenger EVs: a battery that started with 100 kWh of available energy must retain at least 82 kWh after five years and 100,000 km of use. That 82% floor gives pack and cell designers a concrete target for calendar and cycle ageing margin that must be designed in from the outset, rather than a vague durability expectation.
Relevance to Battery Engineering
For BMS and pack engineers, GB/T 46991.1-2025 matters less as a safety requirement and more as a validation target for state-of-health algorithms and ageing models. Teams selling into the Chinese market will need to validate SOCE accuracy against physical capacity measurement across the vehicle’s ageing curve, not just at beginning of life, since the 5% error band has to hold as the cell chemistry ages and impedance grows. It also connects to the EU Battery Regulation‘s own state-of-health and durability disclosure requirements — both regimes are converging on the idea that a battery’s reported health has to be independently verifiable, not just a BMS-reported number taken on trust.
Related Standards
GB 38031-2025 governs traction battery crash and thermal-runaway safety and is unaffected by this standard — a battery pack must satisfy both. GB/T 46991.1-2025 instead sits alongside the EU Battery Regulation’s durability and state-of-health disclosure provisions as part of a broader international trend toward independently verifiable battery health reporting.
References
- GB/T 46991.1-2025, Requirements and test methods for in-vehicle traction battery durability of electric vehicles — Part 1: Light-duty vehicles, effective 1 July 2026.
- China makes EV battery health more transparent, electrive.com, August 2026.
- Can you trust your EV’s battery health reading? China sets new accuracy rules with 5% error limit, CarNewsChina, August 2026.
- GB/T 46991.1-2025 (English Version), Code of China.
- GB 38031, Electric vehicles traction battery safety requirements, Battery Design.
See also: Chinese National Standards (GB)