Abstract: The present invention relates to a method for improving the operational efficiency of a battery pack (100) comprising at least two battery modules (10, 10?, 10?), wherein each battery pack is configured to have a common gas space (29). The method comprises the steps of: obtaining data (101) on the battery modules (10, 10?, 10?), wherein the data relates to the number of battery cells per battery module, the number of battery modules, the temperature of each battery module and the energy capacity of the battery modules; obtaining (102) an indication of the internal resistance (Ri1, Ri2, Ri3) for the battery modules; determining (104), in case a difference in indication parameters between any of the battery modules exceeds a first threshold value, a filling amount of oxygen to be filled into the battery pack; and initiating (107) filling of the battery pack based on the determined filling amount of oxygen.

Abstract: The present invention relates to a method for reconditioning of a battery module (1). The battery module (1) comprises two or more battery cells (2), and has a casing (4) encompassing the battery cells and enclosing a common gas space (5). The method comprises the steps of: obtaining data relating to the number of cells of the battery module and voltage over the battery cells; obtaining (102) an indicative parameter related to an internal resistance (Ri) of at least one of the battery cells; determining (104) based on the indicative parameter and the data on the battery module, determining (105a) whether the voltage indication over the at least one of the battery cells is range of voltage indication threshold (Ut0-Ut1), a filling amount of oxygen to be filled into the battery module; and filling (107) the amount of oxygen into the battery module in order to reduce the indicative parameter to a level below the first threshold value.