NOVELTY - Battery pack (107) optimization system, comprises: a battery pack comprised of at least one metal-air cell and further comprised of a battery pack air outlet and a battery pack air inlet, where the battery pack is configured for use within an electric vehicle (100); a gas tank (125) mounted within the electric vehicle; and a compressor (131) interposed between the battery pack air outlet and the tank inlet, where the compressor configured to compress oxygen-rich effluent from the battery pack air outlet prior to filling the gas tank with the oxygen-rich effluent.    USE - Used as a battery pack optimization system.    ADVANTAGE - The system exhibits improved battery pack efficiency and power capabilities.    DETAILED DESCRIPTION - Battery pack (107) optimization system, comprises: a battery pack comprised of at least one metal-air cell and further comprised of a battery pack air outlet and a battery pack air inlet, where the battery pack is configured for use within an electric vehicle (100) and to provide power to the electric vehicle; a gas tank (125) mounted within the electric vehicle, where the battery pack air outlet is coupled to a tank inlet of the gas tank, and the battery pack air inlet is coupled to a tank outlet of the gas tank; and a compressor (131) interposed between the battery pack air outlet and the tank inlet, where the compressor configured to compress oxygen-rich effluent from the battery pack air outlet prior to filling the gas tank with the oxygen-rich effluent. An INDEPENDENT CLAIM is also included for operating a metal-air battery pack mounted within an electric vehicle, comprising: coupling a battery pack outlet to a tank inlet of a gas tank mounted within the electric vehicle, where the compressor is interposed between the battery pack outlet and the tank inlet; coupling a battery pack inlet to a tank outlet of the gas tank; compressing oxygen-rich effluent passing through the battery pack outlet with the compressor, where the oxygen-rich effluent is at least partially generated by the metal-air battery pack, and the compressing step is performed during a battery pack charge cycle; storing the oxygen-rich effluent compressed by the compressor during the battery pack charge cycle in the gas tank; and transferring the oxygen-rich effluent through the tank outlet of the gas tank to the battery pack inlet of the metal-air battery pack during a battery pack discharge cycle.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of basic elements of a system for collecting, storing and re-using oxygen-rich effluent that is generated during the charge cycle of a metal-air battery pack.    Electric vehicle (100)    Battery pack (107)    Controller (115)    Gas tank (125)    Compressor (131)