A method of determining the state of health of the cells "Ci" of a battery comprising a plurality of series-coupled cells "Ci", the method comprising the steps (201, 202, 203) of: during a phase of discharge or of charge of the battery, measuring and storing the variation of the voltage "Ui" across each cell according to the charge extracted from or injected into the battery "Q", the variation of each voltage "Ui" being ruled by a function "f i " of charge "Q"; when a first cell "Ci lim " reaches a predefined end-of-discharge or end-of-charge condition, interrupting the battery discharge or charge and determining, for each other cell "Ci", the charge variation ΔQ Ci undergone by the battery between: - the passing of the first cell "Ci lim " to a voltage equal to voltage "f i (Q tot)" of each other cell "Ci" at the time of the interruption of the battery discharge or charge phase, and - the interruption of the battery discharge or charge phase; being the charge extracted from the battery or injected into the battery between the beginning of the battery discharge or charge phase and the interruption of the battery discharge or charge phase; supplying, for each other cell "Ci" of the battery, an estimated value of the cell capacity equal to Q tot +ΔQ Ci, and supplying, for each other cell "Ci" of the battery, an indicator of the state of health of the cell calculated by taking into account said estimated value of the capacity Q tot +ΔQ Ci of the cell. during a phase of discharge or of charge of the battery, measuring and storing the variation of the voltage "Ui" across each cell according to the charge extracted from or injected into the battery "Q", the variation of each voltage "Ui" being ruled by a function "f i " of charge "Q"; when a first cell "Ci lim " reaches a predefined end-of-discharge or end-of-charge condition, interrupting the battery discharge or charge and determining, for each other cell "Ci", the charge variation ΔQ Ci undergone by the battery between: - the passing of the first cell "Ci lim " to a voltage equal to voltage "f i (Q tot)" of each other cell "Ci" at the time of the interruption of the battery discharge or charge phase, and - the interruption of the battery discharge or charge phase; being the charge extracted from the battery or injected into the battery between the beginning of the battery discharge or charge phase and the interruption of the battery discharge or charge phase; - the passing of the first cell "Ci lim " to a voltage equal to voltage "f i (Q tot)" of each other cell "Ci" at the time of the interruption of the battery discharge or charge phase, and - the interruption of the battery discharge or charge phase; being the charge extracted from the battery or injected into the battery between the beginning of the battery discharge or charge phase and the interruption of the battery discharge or charge phase; supplying, for each other cell "Ci" of the battery, an estimated value of the cell capacity equal to Q tot +ΔQ Ci, and supplying, for each other cell "Ci" of the battery, an indicator of the state of health of the cell calculated by taking into account said estimated value of the capacity Q tot +ΔQ Ci of the cell.