Abstract: Improved metal-air fuel cell battery systems having metal-fuel realized in the form of metal-fuel tape cartridges and metal-fuel cards, which can be either manually or automatically inserted within the power generation bay of the system. In order to produce a range of output voltages, the metal-fuel tape has a plurality of electrically-isolated metal-fuel tracks and the metal-fuel cards have a plurality of electrically-isolated metal-fuel strips. An output voltage configuration subsystem is provided for configuring the voltages produced by the individual cells to produce a desired output. A subsystem is provided for detecting oxide formation on the metal-fuel tracks and strips so that only metal-fuel that has been oxidized is reduced during recharging operations. A subsystem is also provided for controlling the flow of oxygen into the power generation head in order to control the power output from the system.