UN38.3 Standard Testing Items & Procedures
For lithium batteries or lithium battery packs, a total of 7 items of tests T1 → T5, T6, and T7 are required. However, for lithium battery cells, T1 → T5, T6 and T8 tests are required.
Comparison of UN38.3 & International Standards
Comparison of UN38.3 and IEC62133 Standards
Analysis of UN3813 Standard Test Results & Causes
Problems such as mass loss, leakage, and exhaust during the UN38.3 standard temperature cycle are mainly related to the manufacturing process. Anatomy of the leaked battery revealed that the battery was subjected to uneven force during assembly, which caused the internal insulation plate of the battery to deform, causing the battery to leak at the insulation plate.
In addition, the test also found that some lithium batteries have no mass loss, no leakage, no exhaust, no disintegration, no cracking and no combustion after the temperature cycle test. However, due to the chemical reaction between the positive and negative electrode active materials and the electrolyte inside the battery during the temperature shock, a certain amount of gas was generated, which caused a bulging phenomenon during the test.
However, the swollen lithium battery is more difficult to pass the vibration test during the next high acceleration and long time vibration test. The battery is likely to produce gas leaks and leaks, resulting in excessive quality loss and ultimately failing the vibration test. This requires lithium battery manufacturers in the research and development stage, in addition to continuous improvement of electrical performance, but also must fully consider the adverse impact of temperature shock on lithium battery materials.
Starting with lithium battery materials, the stability of each chemical material at the test temperature specified in the temperature cycle of 75 ℃,-40 ℃, and the transition points between 75 ℃ and-40 ℃ was investigated. Find out which materials are liable to generate gas at the test temperature. Through a large number of experiments to improve the process of these materials, or to find other alternative materials, to seek a better balance between the electrical performance and safety performance of lithium batteries.
In another case, the lithium cell that swelled during the temperature cycle passed the subsequent vibration and shock tests. However, the large amount of gas generated internally during the temperature cycle adversely affects the welding parts around the shell. The pressure shock of the gas directly causes the welding strength to weaken in some areas. In the external short-circuit test after the impact test, the lithium single-cell battery rapidly heated up, and a large amount of gas continued to be generated inside the case. When the internal pressure of the shell rises to a certain value, the gas is released from the area where the welding strength becomes weak, causing the shell to rupture. As a result, the external short-circuit test cannot be passed.