A METHOD FOR ESTIMATING A BATTERY STATE

A method for estimating a battery state of an energy storage system () of a vehicle () using at least a dual estimator (), wherein the energy storage system comprises a battery unit (), and wherein the dual estimator comprises:—a first estimator configured to estimate said battery state using a prediction model, the first estimator having first tuning parameters, —a second estimator configured to track changes around nominal values of a set of battery parameters, the second estimator having second tuning parameters, e a feedback loop being provided between the first and second estimators, the method comprising:—obtaining operational data of the energy storage system, —feeding the operational data to the estimators, —using the first estimator, estimating the battery state, —using g the second estimator, estimating changes around the nominal values of the set of battery parameters, and at least one of:—adaptively adjusting the first and/or the second tuning parameters to account for fast timescale variations due to varying operating conditions, and—adaptively adjusting the nominal values of the set of battery parameters to account for slow timescale variations arising due to ageing.