“Ohmic Measurements” have become a mainstay of modern battery-plant maintenance practices. The basic method consists of instrumentation which forces a known current through a cell and measures the cell’s voltage response to the current. In an ideal cell with infinite current producing capability, the terminal voltage would be invariant to the forcing current. In the real world, cells have current producing limitations which can be analyzed as spurious internal resistances and capacitance. An increase in a cell’s equivalent internal resistance is well known to correlate directly to a corresponding decrease in the cell’s amp/hour capacity. Since steady declines in amp/hour capacity are a leading indicator of the approaching end of the cell’s life-cycle, accurate ohmic measurements made by portable instrumentation or fixed monitoring systems can be a very valuable component of a pro-active battery maintenance program.