The present invention is directed to a vehicular battery system, in particular for electric or hybrid automobiles. The battery system comprises a metal/oxygen battery pack configured to output electrical power, a gas reservoir configured to store oxygenous gas and being operatively coupled to the battery pack to supply oxygenous gas to said battery pack, and a gas cleaning apparatus configured to receive oxygenous gas, in particular ambient air, to clean said gas from contaminants and to supply the cleaned oxygenous gas to said battery pack. In addition, the battery system comprises a battery management system configured to control the supply of oxygenous gas from the cleaning apparatus and the gas reservoir to the battery pack. The battery system has at least two modes of operation, including a first mode that requires a first power output level lower than or equal to a second power level being electrochemically equivalent to the cleaning apparatus' maximum supply rate of oxygen in said first mode of operation, and at least one second mode that requires a third power output level greater than the second power level. The battery management system is configured to control the supply of oxygenous gas to the battery pack such that when the battery system is operated in the first mode, the battery pack is supplied with oxygenous gas output by the cleaning apparatus, and when the battery system is operated the second mode, the battery pack is additionally or instead supplied with oxygenous gas from the gas reservoir.