A new approach is presented to solve the Zn-MnO2 alkaline cell model by exploiting its differential algebraic equation structure. Governing equations for the cell are refined to include a more realistic representation for the open-circuit voltage and the equilibrium relation in the anodic precipitation-dissolution reaction mechanism from experimental data. In order to improve the prediction of cell performance under a wide range of discharge rates at different discharge modes, an effective discharge factor is introduced to account for the charge transfer at the cathode.