Experimental investigation and simulation of thermal and electrical performance of laser welded aluminium-based busbars for electric vehicle batteries

Laser-welded aluminium busbars must sustain high currents while limiting resistive heating in electric vehicle battery packs. This study combines oil-cooled direct-current pulse tests at ambient temperatures of -10 °C, 10 °C, 30 °C, 50 °C and 70 °C and currents of 100 A, 300 A, 500 A and 700 A with three-dimensional COMSOL Multiphysics electro-thermal simulations. Mean joint resistance during the first 60 s ranged from 12.05 µΩ to 17.29 µΩ and increased with current and ambient temperature. At 700 A, peak weld temperature increased from 8.59 °C at an ambient temperature of -10 °C to 84.24 °C at an ambient temperature of 70 °C, corresponding to a measured temperature rise of 13.25 °C. This result demonstrates thermal stacking, while the similar temperature rises at 700 A across the experimental ambient temperatures do not establish a monotonic relationship between temperature rise and ambient temperature. Across the 20 shared experimental and simulated conditions, the mean absolute error in weld temperature was 3.82 °C. The model reproduced the nonlinear current trend but overpredicted temperatures at high currents. The results provide a basis for defining operating limits, cooling strategies, and resistance- or temperature-based weld monitoring.