Abstract: A method for determining the maximum time when a capacitor should be replaced before failure is provided. The method includes obtaining a first group of data relative to the capacitor, the first group of data comprising at least the value of the capacitance of the capacitor and the value of the equivalent series resistance of the capacitor, providing an ageing law for at least the capacitance, an ageing law predicting the evolution with time of a data, computing the remaining lifetime of the capacitor, based on the obtained first group of data, on each provided ageing law and on a lifetime criterion, and determining the maximum time when the capacitor should be replaced before failure, based on the computed remaining lifetime of the capacitor. A device and apparatus are also provided.