Meaning
International transport safety standards mandate thermal shock testing to evaluate battery enclosure seal integrity and internal electrical connection stability under extreme temperature cycling. Test protocols subject lithium cells and packs to alternating temperature extremes of seventy-five degrees Celsius and minus forty degrees Celsius. Executing UN 38.3 T.2 ensures transport safety compliance prior to shipping lithium batteries via commercial air or sea freight channels.
Test requirements stop applying if specimen mass loss exceeds threshold values or internal open circuit voltage drops below ninety percent.
Thermal Cycling
Test chambers rapidly transition test units between upper and lower temperature limits within thirty minutes. Specimen exposure lasts at least six hours at each temperature extreme for a total of ten continuous cycles. Rapid temperature swings induce differential thermal expansion stress across metal casing seams and plastic gaskets.
Chamber control systems maintain strict temperature control during thermal hold periods.
Acceptance Criteria
Post-test evaluation requires zero mass loss exceeding zero point one percent for small cells or zero point two percent for large packs. Voltage retention must remain above ninety-nine point eight percent of pre-test open circuit voltage values. Visual inspection verifies absence of physical cracking, venting, leakage, or internal short circuiting.
Compliance certification allows international commercial transport.
Seal Stress
Mechanical movement resulting from expansion differentials tests hermetic seal durability at gasket and weld interfaces. Rapid contraction under sub-zero temperatures hardens polymer gaskets and lowers sealing pressure. Thermal stress cycling exposes micro-cracks or bond defects in cell enclosures.
Integrity testing protects cargo safety during intermodal transport.
