GB 47741-2026Safety technical specification for batteries used in electric wheelchairs (English PDF)

5 General safety requirements

5.1 General security considerations The safety of batteries and battery packs is considered from two application conditions.

a) Intended use;

b) Reasonably foreseeable misuse, abuse, and malfunction conditions.

5.2 Safe Operating Parameters To ensure the safe use of batteries and battery packs under different conditions, their safe operating conditions should be specified, including temperature range and voltage range. Parameters such as current range. Due to differences in battery material systems and structures, their safe operating parameter values may vary.

6 Battery electrical safety requirements

6.1 High-Temperature External Short Circuit After fully charging the battery according to the test method specified in 4.5.1, place it in an environment of 57 °C ± 4 °C until the battery temperature reaches... After being heated to 57°C±4°C, leave it for another 6 hours. Then connect the positive and negative terminals of the battery with wires, ensuring that the total external resistance is 20 mOmega±5 mOmega. During the test, the battery temperature was monitored. The test was terminated when the battery surface temperature dropped to 57 °C±4 °C and was maintained for another 1 hour. The surface temperature of the battery should not exceed 170 °C. The battery should not disintegrate, crack, or catch fire.

6.2 Overcharging After fully charging the battery according to the test method specified in 4.5.1, charge it with the maximum charging current (Icm) specified by the manufacturer. The battery temperature will be monitored during the test, and the test will be terminated if any of the following conditions are met.

1.5 times the charging limit voltage for 1 hour, then continue constant voltage charging.

b) The total charging time reaches

1.5 hours. The battery should not catch fire or explode.

6.3 Forced Discharge After discharging the battery according to the test method specified in 4.5.2, reverse charge it with a current of 1It until the negative upper limit of the charging voltage. The total charging time is 90 minutes. If the voltage reaches the negative upper limit of battery charging within 90 minutes of reverse charging, the voltage should be maintained by reducing the current to continue charging. The experiment was terminated after reverse charging for a total of 90 minutes, as shown in Case 1 of Figure 1. If the voltage does not reach the negative battery charging upper limit voltage within 90 minutes of reverse charging, the reverse charging test will be terminated after a total of 90 minutes. The test is shown in Figure 1, Case 2.

7 Battery Environmental Safety Requirements

7.1 Low pressure After fully charging the battery according to the test method specified in 4.5.1, place the battery in a vacuum chamber at 20 °C ± 5 °C, and evacuate the chamber. The pressure was reduced to less than or equal to

11.6 kPa (simulated altitude 15,240

m) and maintained for at least 6 hours. The battery should not catch fire, leak gas, disintegrate, crack, or leak liquid. After the test, the open circuit voltage should not be lower than 90% of that before the test.

7.2 Temperature Cycling After fully charging the battery according to the test method specified in 4.5.1, place it in a temperature-controlled chamber at a temperature of 20 °C ± 5 °C for testing. The next step (as shown in Figure 2).

a) Raise the temperature of the test chamber to 72 °C±2 °C and maintain it for 6 h;

b) Reduce the temperature of the test chamber to -40 °C ± 2 °C and maintain this temperature for 6 h;

b) for a total of 10 cycles;

d) Store at room temperature (20 °C ± 5 °C) for at least 24 h. During the experiment, the transition time between any two temperatures shall not exceed 30 minutes. For large batteries, the holding time in

b) should be 12 h.

7.3 Vibration After fully charging the battery according to the test method specified in 4.5.1, secure the battery to the vibration test bench and perform the test according to the parameters in Table 6. String vibration test.

7.10 Lithium plating After repeated charge and discharge cycles, lithium-ion batteries should not release lithium metal that could compromise safety. The following tests are used for detection.

8 Environmental safety requirements for battery packs

Note. This chapter applies to battery packs, as well as the overall sample consisting of a non-user-replaceable battery pack and its electric wheelchair.

8.1 Low pressure After fully charging the sample according to the test method specified in 4.5.1, conduct a low-pressure test, the test method of which is described in 7.1. The sample should not ignite, leak gas, disintegrate, crack, or leak liquid, and the open circuit voltage after the test should not be lower than 90% of that before the test.

8.2 Temperature Cycling After fully charging the sample according to the test method specified in 4.5.1, conduct a temperature cycling test, the test method of which is described in 7.2. For large battery packs weighing more than 12 kg, the holding time specified in 7.2a) and

b) shall be 12 h. The sample should not ignite, leak gas, disintegrate, crack, or leak liquid, and the open circuit voltage after the test should not be lower than 90% of that before the test.

8.3 Vibration After fully charging the sample according to the test method specified in 4.5.1, secure the sample to the vibration test bench with a mass not exceeding 12 kg. The test method for battery packs is given in 7.3; the test method for battery packs with a mass greater than 12 kg is to perform sinusoidal vibration testing according to the parameters in Table 8.

8.5 drop After fully charging the sample according to the test method specified in 4.5.1, it was subjected to free fall dropping from a height of 1 m and in the manner specified in the test method, into a mixed environment. On the concrete slab, the square battery pack has six surface directions, while the cylindrical battery pack has an axial direction and two perpendicular radial directions (both positive and negative). Each test was performed once, for a total of six tests. The time interval between each test was 5 min ± 1 min. After the test, the test was left to stand for 4 hours.

8.6 Stress Relief The structure of a molded or injection-molded thermoplastic shell should ensure that the shell material releases the internal stress generated by the molding or injection molding process. Under stress, any shrinkage or deformation of the outer shell material will not expose the internal components. After fully charging the sample according to the test method specified in 4.5.1, place it in a forced-air constant temperature chamber at 70 °C±2 °C for 7 h, and then remove the sample. The product was then brought back to room temperature.

8.7 Water immersion The sample was fully charged according to the test method specified in 4.5.1. The test sample should be immersed in a saline solution (3.5% NaCl aqueous solution) at room temperature for at least 30 minutes. The water depth should be at least... It did not exceed the highest point of the test sample by 1 cm.

9 Battery Pack Electrical Safety Requirements

9.1 Battery Management System Requirements Battery systems for electric wheelchairs should be designed with a battery management system to ensure that the battery or battery pack operates within its specified operating range. The battery management system should be able to monitor abnormal states of voltage, current, and temperature of batteries and battery packs and take corresponding measures. The system should have the ability to communicate with the vehicle.

9.2 Overvoltage charging protection After fully charging the battery pack according to the test method specified in 4.5.1, conduct the test. --The experiment was conducted under normal protection circuit conditions, with an applied voltage of 1.2 × n × Uup (the upper limit voltage for battery charging), simulating

1.2 times. Overvoltage charging should trigger overvoltage protection; the voltage of any single battery cell should not exceed the maximum charging voltage, and the total voltage of the battery module should be within acceptable limits. It should not exceed n×Uup (the upper limit voltage for battery charging); --The test was conducted under a single fault condition in the protection circuit (simulating faults in each level of the protection circuit separately), with an applied voltage of 1.2 × n × Uup (the upper limit voltage for battery charging), simulating

1.2 times overvoltage charging, should trigger overvoltage protection; the total voltage of the battery module should not exceed [the limit]. Exceeding n×Uup (the upper limit voltage for battery charging). The test shall be stopped when the voltage reaches

1.2 times the overcharge voltage or the protection is triggered. A DC power supply can be used during testing. The power supply voltage is set to an applied voltage of 1.2 × n × Uup (the upper limit voltage for battery charging), and the test current is [not specified]. Set to the recommended charging current (Icr) of the battery pack or m times the recommended charging current of the battery (m×Icr). The battery pack should not catch fire, explode, or leak.

9.3 Overcurrent charging The battery pack was fully discharged according to the test method specified in 4.5.2, and then constant current was applied at

1.5 times the overcurrent charging protection current (1.5Icp). When charging, the battery pack should take protective measures. The battery pack should not catch fire, explode, or leak.

Note. When the overcurrent charging protection current value is a range, the upper limit of the range value is used instead of

1.5 times the overcurrent charging protection current (1.5Icp) during the test.

10 Hz and

55 Hz. For each orientation (vibration direction) of the battery or battery pack placement, in The battery should move back and forth for 95 minutes ± 5 minutes across the entire frequency range, and the test should be conducted at any frequency within the specified range. Three batteries should be used in parallel. Tests were conducted with the vertical orientation [including inverted orientations with the filling port and vent (if any) facing downwards], and the test time was equal for each orientation. After the test is completed, there should be no mechanical damage on the surface of the battery or battery pack, and no electrolyte leakage or other phenomena.

10.3 Differential Pressure Test After the vibration test, when the pressure difference is at least 88 kPa, the battery/battery pack can be stored at 24 °C±4 °C for 6 h. The group was tested in three mutually perpendicular positions for at least 6 hours at each position (including the injection port and vent port, including the inverted position). After the test is completed, there should be no mechanical damage on the surface of the battery/battery pack, and no electrolyte leakage or other phenomena.