In this study, a large-scale segmented cell system was developed to visualize current distribution in
an operating polymer electrolyte membrane fuel cell (PEMFC). Unlike a small-scale segmented cell,
the large-scale segmented cell must resolve several issues such as internal resistance, external
resistance, and PCB/sensor errors. A customized printed circuit board (PCB), a calibration tool, and a
boosting cell were used to solve the issues. Using the large-scale segmented cell, a variation of current
distribution in an operating PEMFC was quantitatively measured under various conditions such as
temperature, pressure, fuel feed, and degradation.