1. Background: From Recommended National Standard to Mandatory Market-Entry Gate
Electric vehicles occupy a clearly defined position as a strategic emerging industry and a core direction of the automotive industry’s future. Under national policy guidance, R&D and industrialisation of energy-saving and new energy vehicles have reached an unprecedented scale, and traction batteries - as the key component driving that growth - have risen in step. In 2016, the Standardisation Administration of China (SAC) issued the revision plan for the mandatory national standard Safety Requirements for Traction Battery of Electric Vehicles (plan no. 20160967-0-339). Building on GB/T 31485-2015 and GB/T 31467.3-2015, and in full alignment with UN GTR 20 - the global technical regulation for electric vehicle safety developed under China’s leadership - the standard was upgraded from recommendatory to mandatory. Three milestones in the timeline:
| Date | Event | Significance |
|---|---|---|
| 2016 | SAC issues the mandatory national standard revision plan (20160967-0-339) | Kicks off the upgrade, aligned with UN GTR 20 |
| 12 May 2020 | Three mandatory national standards - GB 18384-2020 (safety requirements for electric vehicles), GB 38032-2020 (safety requirements for electric buses) and GB 38031-2020 (safety requirements for EV traction batteries) - organised by MIIT and approved by SAMR and SAC | Establishes the mandatory safety floor for vehicles and batteries |
| 1 January 2021 | The three mandatory standards take effect | Becomes the binding basis for product access inspection |
GB 38031-2020 replaces GB/T 31485-2015 and GB/T 31467.3-2015, and serves as the basis for the dedicated inspection items and applicable standards referenced in the Administrative Provisions on Access of New Energy Vehicle Manufacturers and Products. In practice: new energy vehicle and key component manufacturers are required to complete mandatory inspection - known as announcement inspection - before market entry. It is a gate that cannot be bypassed.
2. Mandatory Inspection Requirements by Test Level
Announcement inspection is organised across three levels by object under test: cells, modules, and packs or systems. Each level has its own applicable standards and test matrix.
2.1 Cells: GB/T 31484, GB/T 31486 and GB 38031
| No. | Test item | Test method |
|---|---|---|
| 1 | Appearance | 6.2.1 |
| 2 | Polarity | 6.2.2 |
| 3 | External dimensions and mass | 6.2.3 |
| 4 | Room-temperature discharge capacity | 6.2.5 |
| 5 | Room-temperature capacity and energy | 6.2 |
| 6 | Room-temperature power | 6.3 |
| 7 | Standard cycle life | 6.4 |
| 8 | Overdischarge test | 8.1.2 |
| 9 | Overcharge test | 8.1.3 |
| 10 | External short circuit test | 8.1.4 |
| 11 | Heating test | 8.1.5 |
| 12 | Temperature cycling test | 8.1.6 |
| 13 | Crush test | 8.1.7 |
GB/T 31484-2015 in brief This is the first Chinese national standard to establish cycle performance as a standalone requirement for cells, modules and systems, defining the test methods and rules for both standard cycle life and working-condition cycle life.
| No. | Test item | Acceptance criteria |
|---|---|---|
| 1 | Capacity and energy | Cell: 1-1.1 times rated capacity, cell-to-cell deviation no more than 5%. Module or system: 1-1.1 times rated capacity, deviation no more than 7% |
| 2 | Power | As specified in the product specification |
| 3 | Standard cycle life (cell or module) | Greater than 90% of rated capacity after 500 cycles, or greater than 80% after 1000 cycles |
| 4 | Working-condition cycle life (module or system) | Energy-type for hybrid passenger cars, power-type hybrid commercial vehicles and power-type battery electric passenger cars; energy-type for battery electric commercial vehicles, plug-in hybrid and range-extended electric vehicles. Capacity and 5 s discharge power are assessed when the ratio of total discharged energy to initial rated energy reaches 500 |
GB/T 31486-2015 in brief GB/T 31486-2015 sets new requirements and test methods for the electrical performance of traction battery cells and modules. The number of items assessed at cell level is reduced to four - appearance, polarity, external dimensions and mass, and room-temperature discharge capacity - while module testing expands to eleven items. The national standard strengthens evaluation at module level, providing manufacturers with a testing basis for tighter production quality control, improved product performance, and optimised cell connection methods, structural design and heat transfer design inside the pack.
| Cell type | No. | Test item | Test method |
|---|---|---|---|
| Cell | 1 | Appearance | 6.2.1 |
| 2 | Polarity | 6.2.2 | |
| 3 | External dimensions and mass | 6.2.3 | |
| 4 | Room-temperature discharge capacity | 6.2.5 | |
| Module | 1 | Appearance | 6.3.1 |
| 2 | Polarity | 6.3.2 | |
| 3 | External dimensions and mass | 6.3.3 | |
| 4 | Room-temperature discharge capacity | 6.3.4 | |
| 5 | Room-temperature rate discharge capacity | 6.3.5 | |
| 6 | Room-temperature rate charge capacity | 6.3.6 | |
| 7 | Low-temperature discharge capacity | 6.3.7 | |
| 8 | High-temperature discharge capacity | 6.3.8 | |
| 9 | Charge retention and capacity recovery | 6.3.9 | |
| 10 | Vibration resistance | 6.3.10 | |
| 11 | Storage | 6.3.11 |
2.2 Packs and Systems: GB 38031-2020
While optimising safety requirements for cells and modules, GB 38031-2020 places emphasis on strengthening battery system thermal safety, mechanical safety, electrical safety and functional safety. Test items cover system thermal propagation, external flame exposure, mechanical shock, simulated crash, damp heat cycling, vibration followed by water immersion, external short circuit, over-temperature and overcharge. Most significant is the newly added battery system thermal propagation test: after a single cell enters thermal runaway, the battery system shall not fire or explode within five minutes, reserving an escape window for occupants.
| Category | No. | Test item | Test method |
|---|---|---|---|
| Pack or system | 1 | Vibration test | 8.2.1 |
| 2 | Mechanical shock test | 8.2.2 | |
| 3 | Simulated crash test | 8.2.3 | |
| 4 | Crush test | 8.2.4 | |
| 5 | Damp heat cycling test | 8.2.5 | |
| 6 | Water immersion test | 8.2.6 | |
| 7 | Thermal stability - external flame exposure | 8.2.7.1 | |
| 8 | Thermal stability - thermal propagation | 8.2.7.2 | |
| 9 | Temperature shock test | 8.2.8 | |
| 10 | Salt spray test | 8.2.9 | |
| 11 | High-altitude test | 8.2.10 | |
| Battery system | 12 | Over-temperature protection test | 8.2.11 |
| 13 | Over-current protection test | 8.2.12 | |
| 14 | External short circuit protection test | 8.2.13 | |
| 15 | Overcharge protection test | 8.2.14 | |
| 16 | Overdischarge protection test | 8.2.15 |
3. Test Items, Methods and Acceptance Criteria
This is the section engineers consult most often before submission. Every item is reproduced in full.
3.1 Cells - Test Items, Methods and Safety Requirements under GB 38031
| Test item | Method | Safety requirement | Method notes |
|---|---|---|---|
| Overdischarge | 8.1.2 | Shall not fire or explode | Discharge at 1C for 90 min |
| Overcharge | 8.1.3 | Shall not fire or explode | Charging current: as specified by the manufacturer and not less than 1C₃. Cut-off condition: 1.1 times the charging termination voltage specified by the manufacturer, or 115% SOC. The test ends as soon as either the voltage limit or the SOC limit is reached |
| External short circuit | 8.1.4 | Shall not fire or explode | External short circuit resistance less than 5 mΩ, shorted for 10 min |
| Heating | 8.1.5 | Shall not fire or explode | Lithium-ion cells: 5°C/min ramp, heated to 130°C ± 2°C and held for 30 min. Nickel-metal hydride cells: 5°C/min ramp, heated to 85°C ± 2°C and held for 2 h |
| Temperature cycling | 8.1.6 | Shall not fire or explode | Specific temperature and time parameters per Table 1 and Figure 1 of the standard (7 to 85°C, and -7 to 40°C, 480 min cumulative per cycle); five cycles |
| Crush | 8.1.7 | Shall not fire or explode | Crush direction perpendicular to the electrode plate direction, or the direction in which the cell is most susceptible to crushing in vehicle layout. Crush plate: a half-cylinder of 75 mm radius, with length greater than the cell dimension. Crush speed not greater than 2 mm/s. Degree of crush: 0 V, or 15% deformation, or 100 kN, or 1000 times the mass of the test specimen, held for 10 min |
Key points for the crush test:
- Crush speed refers to the speed at which load is applied to the cell and must meet the stated requirement.
- 15% deformation means the deformation reaches 15% of the cell dimension along the crush direction.
- Testing stops as soon as any one of the four crush cut-off conditions is met.
3.2 Packs and Systems - Test Items, Methods and Safety Requirements
Mechanical and environmental robustness
| Test item | Method | Safety requirement | Method notes |
|---|---|---|---|
| Vibration | 8.2.1 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | Starting SOC not less than 50% of the manufacturer’s specified normal working range; random and fixed-frequency vibration applied separately along three axes; differentiated for M1 and N1 class vehicles versus other vehicle types, with parameters per clause 5.2.1 |
| Mechanical shock | 8.2.2 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | 7 g, 6 ms half-sine shock waveform; applied in the z axis; six shocks in each of the positive and negative directions; interval between successive shocks not less than five times the shock pulse duration |
| Simulated crash | 8.2.3 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | Test directions x and y; where multiple mounting directions exist, test in the direction with the greater acceleration |
| Crush | 8.2.4 | Shall not fire or explode | Crush plate: one of two types; x and y directions may be executed on separate specimens; crush speed not greater than 2 mm/s; degree of crush 100 kN or 30% deformation along the crush direction; held for 10 min |
| Damp heat cycling | 8.2.5 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V within 30 min after testing | Executed per GB/T 2423.4, test Db; maximum temperature 60°C or higher where the manufacturer specifies higher; five cycles. x and y direction crush tests may be run on separate specimens but must use the same crush plate |
| Water immersion | 8.2.6 | Method 1: shall not fire or explode. Method 2: shall meet IPX7 after testing, with no leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | Specimens shall have passed the 8.2.1 vibration test, with wiring harnesses, connectors and related components connected in the vehicle-level configuration. Method 1: real vehicle mounting orientation, immersed 2 h in 3.5% sodium chloride solution. Method 2: per GB/T 4208-2017 clause 14.2.7 (IPX7) |
| Thermal stability - external flame exposure | 8.2.7.1 | Shall not explode | Vehicle body structures that protect the pack or system may participate in the test; ambient temperature above 0°C, wind speed not greater than 2.5 km/h; fuel pan extending 20 cm to 50 cm beyond the horizontal projection of the specimen; pan height not more than 8 cm above the fuel surface; specimen placed centrally; distance between the fuel surface and the bottom of the specimen 50 cm, or the ground clearance of the specimen bottom with the vehicle at kerb weight; preheat 60 s, direct flame 70 s, indirect flame or a second direct flame 60 s, then removed from the flame source. Timing reference: the 70 s direct flame period starts when the specimen edge aligns with the pan edge; the 60 s indirect flame period starts when the firebrick edge aligns with the pan edge |
| Thermal stability - thermal propagation | 8.2.7.2 / Annex C | Thermal propagation occupant protection analysis and verification shall be performed | Specimens may be a pack, a system or a complete vehicle. The manufacturer provides documentation of the thermal event alarm signal and safety technical documentation, and the test laboratory issues a verification report based on that documentation. Requirement: a thermal event alarm signal shall be provided not less than 5 minutes before thermal runaway of a single cell leads to thermal propagation and thereby places the occupant cabin in danger, where “danger to the occupant cabin” is interpreted as smoke entering the cabin, or fire or explosion occurring |
| Temperature shock | 8.2.8 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | -40°C ± 2°C to 60°C ± 2°C, or more severe values where specified by the manufacturer; transition time within 30 min; eight hours at each extreme temperature; five cycles |
| Salt spray | 8.2.9 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | Specimens located entirely in the occupant cabin, luggage compartment or cargo compartment may be exempt; per GB/T 28046.4-2011 clause 5.5.2 and GB/T 2423.17 conditions; sprayed at 35°C ± 2°C for 8 h, then rested 16 h, with low-voltage powered monitoring between hour 4 and hour 5 |
| High altitude | 8.2.10 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | Air pressure 61.2 kPa, simulating 4000 m altitude; rested 5 h, then discharged at a current as specified by the manufacturer and not less than 1C₃ down to the manufacturer’s specified discharge cut-off condition. Test environment: 61.2 kPa, 22°C ± 5°C |
Electrical protection
| Test item | Method | Safety requirement | Method notes |
|---|---|---|---|
| Over-temperature protection | 8.2.11 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | All relevant protection devices shall operate normally, except the cooling system; continuous charge and discharge to raise temperature as quickly as possible; temperature raised from 20°C ± 10°C or higher until the over-temperature protection threshold or the manufacturer’s specified maximum working temperature is reached. Test ends on any of: automatic termination or restriction of charge/discharge; a signal is emitted to terminate or restrict charge/discharge; temperature stabilises (less than 4°C change within 2 h). The test termination condition supplied by the manufacturer shall be higher than its defined internal over-temperature protection threshold or specified maximum working temperature |
| Over-current protection | 8.2.12 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | Applies to battery systems that can be supplied by an external DC source; temperature 20°C ± 10°C, SOC in the middle of the normal working range; once the manufacturer’s specified maximum normal charging current is reached, the current is increased to the over-current level of a failed external DC supply within 5 s and charging continues. Test ends on any of: automatic termination of charging current; a signal is emitted to terminate charging; temperature stabilises (less than 4°C change within 2 h) |
| External short circuit protection | 8.2.13 | No leakage, no rupture of the enclosure, no fire or explosion; insulation resistance not less than 100 Ω/V after testing | Temperature 20°C ± 10°C or higher where required by the manufacturer; all relevant protection devices operating normally; positive and negative terminals connected with short circuit resistance not greater than 5 mΩ; the short is maintained until either the protection function operates and interrupts the short circuit current, or the enclosure temperature stabilises (less than 4°C change within 2 h) and the short is held for at least a further 1 h |
| Overcharge protection | 8.2.14 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | Temperature 20°C ± 10°C or higher; SOC in the middle of the normal working range; all protection devices affecting test function and results shall operate normally; charging control limits in the external charging equipment shall be disabled; charging continues using the shortest charging strategy permitted by the battery system manufacturer until: (a) the specimen automatically terminates charging current; (b) a signal is emitted to terminate charging current; (c) where overcharge protection does not operate, or condition (a) is absent, charging continues until temperature exceeds [maximum working temperature + 10°C]; (d) where charging current is not terminated and specimen temperature remains below [maximum working temperature + 10°C], charging continues for 12 h |
| Overdischarge protection | 8.2.15 | No leakage, no rupture of the enclosure, no fire or explosion, and no abnormal termination condition triggered; insulation resistance not less than 100 Ω/V after testing | Temperature 20°C ± 10°C or higher; SOC at a low level; all relevant protection devices operating normally; discharge continues at a stable current within the manufacturer’s specified normal working range until: (a) the specimen automatically terminates discharge current; (b) a signal is emitted to terminate discharge current; (c) where the automatic interrupt function does not operate, or condition (a) is absent, discharge continues to 25% of rated voltage; (d) temperature stabilises (less than 4°C change within 2 h) |
4. Test Cycle and Sample Submission
| Product | Cycle | Sample quantity |
|---|---|---|
| Cell | 3-4 months (including cycling) | 11 cells (the report also covers module-level content, plus 11 modules) |
| Pack or system | 3-4 weeks | 6 units |
Notes on sample submission:
- The long cell-level cycle is driven mainly by cycle life testing. GB/T 31484 requires greater than 90% of rated capacity after 500 cycles, or greater than 80% after 1000 cycles. Allow adequate schedule margin.
- Because the cell report also outputs module-level content, an additional 11 modules are required. Omitting them results in a second round of sample submission and schedule slippage.
- Before pack or system testing begins, confirm that wiring harnesses, connectors and related components are connected in the vehicle-level configuration. Water immersion and short circuit tests are sensitive to connection state.
5. Why SRC-TEST
Why choose SRC-TEST for power battery mandatory inspection:
- Comprehensive accreditation. Laboratories accredited by CNAS, CMA and A2LA, covering both mandatory Chinese national standards (GB) and international certification (E-mark, ECE R136), so the same programme does not require submission to multiple laboratories.
- Full battery test capability across all levels. Covering electrical performance (GB/T 31484, GB/T 31486), safety (GB 38031), environmental reliability (high and low temperature, damp heat, vibration, salt spray, high altitude) and failure analysis, covering the complete chain from cell to pack.
- Equipment and environments. Electrochemical workstations, charge and discharge cycling systems, battery safety test chambers for thermal propagation and external flame exposure, high and low temperature environmental chambers, vibration tables for random and fixed-frequency testing, salt spray chambers, and EMC anechoic chambers - sufficient to meet the four cell items, eleven module items and sixteen system items above.
- Experienced engineers. Senior test engineers with an average of more than ten years in the field, familiar with the decisive criteria such as BMS protection threshold validation and thermal event alarm signal verification, able to provide a pre-submission design compliance review.
- End-to-end support. One-to-one support throughout, from scheme design and sample preparation to submission follow-up and retesting after remediation.
Note: The exact combination of test items depends on the product form factor (cell, module or pack), vehicle type (passenger, commercial or special-purpose) and the applicable mandatory certification route. Contact an SRC-TEST engineer for a tailored test plan and quotation.