A method manages a state of charge of a traction battery of a rechargeable hybrid vehicle including a hybrid power train to provide propulsion. The battery being capable of operating according to a first operating mode over a state of charge range, of which an amplitude is bounded by predefined maximum and minimum state of charge values, in which the battery supplies substantially all power necessary for propulsion, and a second operating mode, in which the state of charge of the battery is kept substantially constantly around an equilibrium state of charge value. The method includes estimating an ageing state of the battery, comparing the estimated ageing state of the battery in relation to a given ageing state threshold, and reducing the amplitude of the state of charge range linked to the first operating mode when the ageing state of the battery rises above the given ageing state threshold.