Two different Zn-based batteries are tested, simultaneously recording the voltage of the negative and positive electrodes during the discharge/charge processes to evidence the advantages of using a three-electrode cell, including a pseudo-reference electrode, with respect to the normally applied two electrodes system. The three-electrode cell allows us to identify in each moment which electrode reveals unexpected events during a battery test and thus to act on it accordingly. In this work, alkaline Zn/Bi2O3 and Zn/air batteries, including a pseudo-reference electrode, are subjected to different galvanostatic discharge/charge tests, highlighting several unforeseen changes and failures in both negative and positive electrodes. Thus, the usefulness of using a three-electrodes system in Zn-based batteries is revealed because it allows us to explain what the cause of the battery failure was and, if necessary, to act immediately. Finally, Spectroscopic Impedance measurements are also applied to a specific case of the Zn/Bi2O3 battery using the same three-electrode cell.