Real-time electro-thermo-mechanical performance evaluation of laser welded AA 1050 busbar

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The efficiency of electric vehicle battery packs is dependent upon the quality of the lithium-ion cell to busbar connection. The busbars of battery packs are increasingly being constructed using aluminium alloys. Laser welding method is gaining popularity to weld busbars to cell terminals, but it requires a comprehensive evaluation. In literature, weld resistance and thermal behaviour are assessed separately from mechanical strength to evaluate joint performance. However, joint resistance and temperature in the absence of external mechanical loading are not representative of in-service loading which may promote failure of the weld between the busbar and terminal. This paper presents a novel evaluation system (real-time) that simultaneously measures resistance, temperature and mechanical strength for lap-shear and torsion joint configurations. In this approach, the weld is subjected to a continuous loading and resistance and temperature are measured. The real-time change in resistance and temperature was monitored continuously from zero to until the load dropped to 80 % of the peak value at different current amplitudes (i.e. 100 A, 150 A, and 200 A). A resistance increase of approximately 51 %, 62 %, and 71 % was observed at the end of the test for 100 A, 150 A and 200 A currents in lap joint samples, while a resistance change of 28 %, 45 %, and 60 % was observed in torsion test samples. In addition, the temperature captured at peak load for 200 A was around 146 % higher than the initial value for the lap shear sample and 139 % higher for the torsion test sample. • Joint resistance and temperature were evaluated simultaneously under both loaded and unloaded conditions. • Real-world operating conditions were replicated by applying lap shear and torsion loads. • This study provides a versatile and effective method for evaluating laser-welded joints. • Findings can contribute to battery pack design, enhance reliability and extend the life cycle of Li-ion battery cells.