A system and a method are for estimating an operating parameter value of an energy storage device arranged to provide power for propulsion for an electric or hybrid vehicle. In an embodiment, the method includes determining a first operating parameter value of the energy storage device at a first time; establishing a reference operating parameter value from pre-determined experimental data relating the operating parameter to a time related parameter; and based on the reference operating parameter value and the first operating parameter value, recursively calculating a second operating parameter value of the energy storage device at a second time subsequent to the first time. The recursive calculation includes a tuning parameter for modifying a portion of the reference operating parameter value to be included in the second operating parameter value.