When converting an EV cell line for ESS use, retrofit effort and budget tend to concentrate on the assembly process. However, when a thick-film electrode and a large prismatic cell format are applied simultaneously while the drying-oven length remains fixed, the takt-time margin in the assembly section increases by 87.3% while the coating-section line speed drops by 40.9%. The conversion bottleneck shifts from assembly to the electrode section, and CAPEX priority should be reallocated accordingly. Furthermore, failing to update the abnormal-cycle-time baseline by part number books up to 36.3 percentage points of phantom performance loss into OEE, causing the improvement organization to chase a loss that does not exist. 1.…