A hybrid battery pack has a first battery (10) with a plurality of first cells (11) connected in series and a second battery (20) with a plurality of second cells (21) connected in series. The first battery (10) and the second battery (20) each have a different chemistry and are connected in parallel. A method for identifying batteries having an optimum combination for a hybrid battery pack includes obtaining information related to a load profile (100) for an electric device in which the hybrid battery pack is adapted to be used. Further, information about an initial state of charge (101) of each cell in the first and the second battery (10 and 20) respectively and information related to the number of the cells and a nominal capacity of each battery string (103) is obtained. The information thus obtained is sent to an equivalent circuit (104) for determining the optimum combination.
