Voltage withstand test of battery pack

1. Purpose of battery pack testing:
Verify the anti breakdown ability of the insulation layer of the battery pack under extreme voltage, and actively expose hidden defects in the insulation layer (such as tiny pinholes and local weak points in the material).
Simulate abnormal working conditions such as overvoltage and short circuit to ensure that the battery pack will not experience breakdown, flashover or leakage under high voltage environment, ensuring safe use.
2. Testing standards
AC voltage withstand test: Typically, a 50Hz-60Hz sine waveform is used, with an effective value of 2U+1000V2U+1000V2U+1000V (UUU is the highest voltage of the battery pack). For example, the test voltage for a 500V system is 2000V AC, and the equivalent DC voltage is 2828V DC.
DC withstand voltage test: Some standards or enterprises may use DC voltage for testing, and the voltage value is generally equivalent to the equivalent DC voltage of AC withstand voltage test, or set according to specific requirements.
3. Test parameters
Test voltage: Calculated based on the highest voltage UUU of the battery pack, as shown in the above formula. Different standards or companies may have slight differences, and specific requirements shall prevail.
Test time: The voltage holding time is 1 minute, and the boosting time should be ≥ 10 seconds to avoid sudden voltage changes impacting the insulation layer.
Leakage current threshold: generally set to ≤ 1mA or determined according to project requirements. If the leakage current exceeds the threshold, it is considered as a test failure.
4. Test object
The insulation layer between the overall high-voltage circuit of the battery pack and the shell.
Insulation between high-voltage interfaces (such as charging ports, motor interfaces) and the casing.
5. Testing methods
Use a voltage tester to apply high voltage between the high voltage terminal of the battery pack and the casing, or between the high voltage interface and the ground.
During the testing process, monitor whether there is breakdown or flashover of the insulation layer, and record the leakage current value.
Partial testing requires confirmation of different polarities or wiring methods to ensure comprehensive coverage of possible fault paths.
6. Testing instruments
Meric: RK9920 programmable AC/DC withstand voltage insulation tester. Coverage testing items: AC withstand voltage, DC withstand voltage, insulation testing. Meet the voltage withstand insulation test of the battery pack. Equipped with a dedicated upper computer program for testing, scanning and recording test parameters, it can achieve secondary development and transfer data to the MES system.

7. Precautions
Before testing, it is necessary to ensure that the battery pack is powered off and the low-voltage circuit is isolated to prevent the test voltage from forming an unexpected path through the low-voltage circuit.
Operators need to wear protective equipment such as insulated gloves and insulated shoes, do not wear metal products on their bodies, and strictly comply with safety regulations.
If insulation failure occurs during the testing process, the cause should be promptly investigated to avoid damage to the battery pack or testing equipment.
The voltage withstand test of battery packs is an important part of ensuring the safety and reliability of batteries. It must be strictly operated in accordance with standards and specifications to ensure the accuracy and effectiveness of the test results.