GB/T 31467.2-2015[Replaced by GB/T 31467-2023] Lithium-ion traction battery pack and system for electric vehicles -- Part 2: Test specification for high energy applications (English PDF)

3.1 Battery electronics

Electronic device that collects and possibly monitors thermal and electric data of batteries or battery assemblies, and contains electronics for cell balancing, if necessary.

3.2 Battery control unit. BCU

Electronic device that controls or manages or detects or calculates electric and thermal functions of the battery system and that provides communication between the battery system and other vehicle controllers.

3.3 Rated capacity of battery pack / system

Total number of ampere hours that can be withdrawn from a battery and declared by the manufacturer under specified conditions.

3.4 Battery pack

Mechanical assembly comprising battery cells, battery management modules (except BCU), and battery box and the corresponding accessories, obtaining power from outside and exporting electricity.

3.5 Battery system

Energy storage device that includes batteries or battery assemblies or battery pack(s) as well as appropriate accessories (management system, high-voltage circuit, low-voltage circuits, thermal management, and mechanical equipment assembly).

3.6 High energy application

Characteristic of device or application, for which the numerical ratio between maximum allowed electric power output and electric energy output at a 1C discharge rate at RT for a battery pack or system is typically lower than 10.

3.7 High power application

Characteristic of device or application, for which the numerical ratio between maximum allowed electric power output and electric energy output at a 1C discharge rate at RT for a battery pack or system is typically equal to or higher than 10.

5.1 General conditions

5.1.1 If not otherwise specified in certain specific test projects, the test shall be conducted at RT of 25°C±2°C and of which the humidity is 15%~90%.

5.1.2 The necessary documentation for operation and needed interface parts

for connection to the test equipment (i.e. connectors, plugs including cooling) shall be delivered, and the typical structure of battery pack and system refers to Appendix A.

5.1.3 When test target ambient temperature changes, test sample needs to

complete the process of adaptation to the environment before test starts. place it at low temperature for not less than 24h; at high temperature for not less than

16h; or temperature difference between cell ambient temperature and target temperature shall not exceed 2°C. If test sample contains BCU, it needs to turn it off during environment adaption.

5.1.4 If battery pack or system is not suitable for some tests due to reasons like size or weight, etc., it shall use subsystem of battery pack or battery system as test sample after agreed by both parties for all or some tests. However, this subsystem shall contain all parts related to vehicle requirements.

5.1.5 The method of adjusting SOC to test target value n%. charge battery pack or system according to charging method provided by the manufacturer, place it for 1h and discharge constant current at 1C discharge rate at (100-n)/100h.

After each SOC adjustment, place test sample for 1h before new test starts.

5.1.7 The discharge rate during the test shall be in accordance with the provisions in this Part. Charging mechanism and cut-off conditions of discharging shall be provided by the manufacturer. However, these conditions shall be unified, for example, charging mechanism and discharging mechanism during cycle performance test shall be same with the provisions of other tests.

5.1.8 Rated capacity of battery pack or system has an important influence on the testing process. If absolute difference between actual available capacity of battery (7.1.2.2) and battery rated capacity exceeds 5% of rated capacity, it shall be clearly stated in the test report, and replace rated capacity by actual available capacity, as the reference to calculation of charge and discharge current, and SOC.

5.1.9 Test items, test methods clause number, test conditions for battery pack

and system are shown in Appendix B.

5.1.10 Battery discharge current sign is positive while charge current sign is negative.

5.2 Accuracy requirements

5.4 Test preparation

5.4.1 Battery pack preparation

Connect high pressure, low pressure and cooling devices of battery pack to test bench equipment. Activate passive protection of battery pack. Test the working state and operating parameters of bench detection and control battery pack based on battery pack manufacturer requirements and test procedures. Ensure that active protection is activated.

5.4.2 Preparation of battery system

Connect high pressure, low pressure and cooling devices of battery pack as well as BCU to test bench equipment. Activate active protection and passive protection of battery system.

5.4.3 Mass and volume of test sample

Use measuring tool to measure dimensions of test sample. Calculate test sample’s volume, in L. Use weighing apparatus to measure test sample’s mass, in kg. If test sample contains forced cooling system, it shall be included such as cooling circuit when measuring or calculating its mass and volume. If cooling system adopts liquid cooling, the mass of cooling liquid shall be counted. If test sample’s cooling system is integrated with the vehicle or other cooling systems, it shall only consider the mass and volume of the part related to test sample. If it is difficult to measure, it shall use data provided by the manufacturer and data test reference.

6.1 Preprocessing cycle

6.1.1 Conduct preprocessing cycle for battery pack or system at RT before

official test starts. The procedures are as follows.

6.1.2 If continuous discharging capacity change twice of battery pack or system

is not greater than 3% of rated capacity, it shall be regarded that battery pack or system has completed the preprocessing. And preprocessing cycle can be aborted.

6.2 Standard cycle

6.2.1 Conduct it according to test procedures specified in this Part during testing

process at RT. It shall follow a sequential order including a standard discharging process and a standard charging process. The procedures are as follows.

6.2.2 If the interval between standard cycle and a new test is longer than 24h, it shall re-conduct a standard charging.

6.2.3 The ambient temperature of “standard cycle” mentioned in this Part refers

to room temperature (RT). And the ambient temperature of “standard discharging” and “standard charging” mentioned separately shall be conducted according to specific provisions.

7.1 Capacity and energy

7.1.1 General conditions

7.1.1.1 Capacity and energy at RT, high temperature and low temperature shall be detected for battery pack or system.

7.1.1.2 Detect test sample before each charging. Place it for 30 min or till it reaches to RT.

7.1.1.3 Use constant current discharging during testing process. Stop

discharging till it meets cut-off conditions specified by manufacturer.

7.1.2 Capacity and energy test at RT

7.1.3 Energy and capacity test at high temperature

Battery pack and system require 1C and Imax(T) energy and capacity test at

40°C. Conduct the test according to test procedures in Table 2.

7.1.4 Energy and capacity test at low temperature

Battery pack and system require 1/3C, 1C and Imax(T) energy and capacity test at 0°C~20°C. Conduct the test according to test procedures in Table 3.

7.2 Power and internal resistance

7.2.1 General conditions

7.2.1.1 Battery pack or system requires power and internal resistance test at

RT, high temperature and low temperature as well as different SOC. The whole testing process shall be in accordance with 7.2.4.

7.2.1.2 Measure terminal voltage of battery pack or system at the time given in

Table 5.Calculate charging and discharging power and internal resistance according to 7.2.3.

7.2.2 Power and internal resistance test conditions

7.2.2.1 Power and internal resistance test conditions shall be in accordance with Table 4 and Figure 1.Data required recording during testing process are shown in Table 5 and Figure 2.

7.2.2.3 Charging current during charging shall be maintained as constant current. The current value shall be 0.75I’max (SOC, T, t). If the maximum allowable pulse charging current of battery pack or system is less than 0.75 I’max (SOC,

T, t), the charging shall be conducted based on the maximum allowable charging current specified by manufacturer.

7.2.3 Power and internal resistance calculation

7.2.3.1 Discharging internal resistance calculation

7.2.3.2 Charging internal resistance calculation

Calculate charging internal resistance according to equation (13) ~ equation (16).

7.2.3.4 Charging power calculation

Calculate charging power according to equation (28) ~ equation (31).

7.2.4 Test procedures

Power and internal resistance test at RT, high temperature and low temperature shall be separately conducted according to Table 6, Table 7 and table 8.And the ones at high temperature and low temperature shall be conducted in environmental chamber.

7.3 No-load capacity loss

7.3.1 No-load capacity loss refers to the capacity loss during long time shelving

when battery system is under in-car status, including recoverable capacity loss and non-recoverable capacity loss. The test shall follow Table 9 and Table 10.

7.3.2 This test is only applicable to battery system.

7.3.3 Battery management system shall be powered by an auxiliary power during shelving, and working condition shall be specified by manufacturer.

7.3.4 In no-load capacity loss test, battery system to be tested shall be in full power state specified by manufacturer.

7.3.5 No-load capacity loss shall be detected at two different temperatures, i.e., RT and 40°C.

7.3.6 Test period is 168h (7 days) and 720h (30 days).

7.3.7 After shelving is completed, detect no-load capacity and energy loss.

7.4 Capacity loss in storage

7.4.1 Capacity loss in storage refers to capacity loss of battery system in long time storage. The test shall be conducted according to Table 11.

7.4.2 This test is only applicable to battery system.

7.4.3 In storage, disconnect high temperature connection and low temperature

connection of battery system, turn off cooling system and other necessary connecting devices.

7.4.4 In storage, battery system SOC is 50% (or negotiated by manufacturer and customer).

7.4.5 Storage temperature is 45°C.

7.4.6 Storage period is 720h.

7.4.7 After storage is completed, detect the remaining capacity of battery system so as to determine capacity loss rate of battery system.

7.5 Energy efficiency

7.5.1 Energy efficiency test aims to detect the performance and energy cycle

efficiency of battery system at different temperature and different magnification during charging.

7.5.2 This test is only applicable to battery system.

7.5.3 Energy efficiency test shall be conducted at three different temperatures, i.e., RT, 0°C and Tmin (negotiated by manufacturer and customer).

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