A mathematical model has been developed that can predict the potential and current‐density distributions on the electrode of a lead‐acid cell. A measured voltage‐current relationship was used for the model according to the depth of discharge and acid concentration. A finite difference method with fine mesh was adopted to resolve it precisely. Detailed information about the potential and current‐density distributions was obtained. Discharge behavior was simulated taking electrolyte stratification into account. Good agreement was found between predictions and observations.