An object of the present invention is to estimate deterioration parameters for various storage batteries, evaluate deterioration of the storage batteries, and predict their lifespans.
A method of estimating a plurality of deterioration parameters by fitting a voltage-capacity curve and a resistance-capacity curve of a positive electrode and a negative electrode to a voltage-capacity curve and a resistance-capacity curve of a storage battery, and evaluating the deterioration of a storage battery, Determine whether the health of the battery is higher than a predetermined value, if the health of the battery is higher than the predetermined value, search for a single set of degradation parameters, and if the health of the battery is less than or equal to the predetermined value. In this method, it is determined that the storage battery has deteriorated over time, and model optimization is performed by fitting the voltage capacity curve for some of the multiple fitting parameters.