Meaning
Leak detection in a sealed test chamber measures the pressure rise that occurs as gas escapes from a test object under vacuum. For battery manufacturing lines, vacuum decay provides a fast, dry and non-destructive method to test the hermetic seal of pouch and prismatic cells. It provides a reliable way to screen out cells with micro-leaks.
Leak Evaluation
Test chambers are evacuated to a high vacuum before the system isolates the chamber and monitors the pressure rise. During the vacuum decay test, any leak in the pouch cell will allow gas or volatile electrolyte solvents to escape into the chamber. This causes a measurable pressure rise over a short period.
This method can detect both large defects and fine micro-leaks.
Sourcing Benefit
Battery pack assemblers choose this technology to ensure high seal quality across all sourced cells. Sourcing managers request vacuum decay test data from their cell suppliers to confirm that the seals will survive long-term exposure to the elements. This prevents the selection of cells that might leak after a few thousand hours of operation.
It reduces the risk of expensive warranty claims and ensures high system safety.
Equipment Threshold
Transducer sensitivity is the key factor that determines the minimum leak size that can be detected. If the transducers are not highly sensitive, the vacuum decay test will fail to identify very small leaks that could still allow moisture ingress over several years. Sourcing specifications should define the minimum detectable leak rate and require the use of high-resolution sensors.
This ensures that the testing equipment is capable of meeting the rigorous quality standards of the automotive industry.
