Busbar welds play a pivotal role in battery pack assembly, as their quality significantly impacts the structural integrity, electrical conductivity, and thermal efficiency of the battery pack. Current in-line quality evaluation methods encompass diverse techniques, including resistance measurement, thermographic imaging for fusion area assessment, machine vision for weld surface scanning, and monitoring of spectral line intensities during the welding process. This research delves into the efficacy of several approaches across various production scenarios, considering the inherent variations in the production processes. Typical variations in laser power, gap condition, laser focus condition, surface contamination, weld location etc are considered and result in welds with different qualities. Process spectrum, weld surface morphology and resistance measurement data are meticulously analyzed by correlating them with joint strength derived from tensile testing. Porosity distributions characterized by X-ray are used for quality evaluation. The study reveals that weld surface morphology from machine vision and spectral line intensity data exhibit strong correlations with process variations and weld strength. Conversely, resistance data proves to be less sensitive to process changes and does not correlate well with weld strength and porosity levels. In summarizing the findings, this study offers recommendations on effective in-line inspection for ensuring the quality of busbar welds in production environments.