METHOD FOR ESTIMATING AN OPERATING PARAMETER OF A BATTERY UNIT

A method for estimating an operating parameter of a battery unit () in an energy storage system () of a vehicle () using a set of first estimators, each first estimator being configured to estimate a state residual size of the battery unit based on a given initial value of said operating parameter and using a prediction model, the operating parameter being indicative of one of capacity and impedance of the battery unit, the method comprising:—obtaining measurement data relating to operating conditions of the energy storage system at a number of points in time t,—providing a set of initial values of said operating parameter, each initial value being associated with one of said first estimators,—using the set of first estimators, estimating () a set of state residual sizes of the battery unit at each point in time tbased on at least the measurement data and on the associated initial values,—determining a first operating parameter estimate of the battery unit based on the estimated set of state residual sizes,—estimating the operating parameter of the battery unit as a function of time based on at least said first operating parameter estimate, wherein estimating the set of state residual sizes comprises using a recursive algorithm for estimating the state residual size of each element of a set of state residuals, each estimated state residual size being determined based on the state residual size as estimated at a previous point in time tand a current magnitude of the state residual.