US 12,461,165 B2
Method for balancing battery modules
Yang Shen, Gävle (SE); and Stina Starborg, Sollentuna (SE)
Assigned to Nilar International AB, Täby (SE)
Appl. No. 17/906,705
Filed by Nilar International AB, Täby (SE)
PCT Filed Mar. 25, 2021, PCT No. PCT/SE2021/050262
§ 371(c)(1), (2) Date Sep. 19, 2022,
PCT Pub. No. WO2021/201748, PCT Pub. Date Oct. 7, 2021.
Claims priority of application No. 2050360-3 (SE), filed on Mar. 31, 2020.
Prior Publication US 2023/0176139 A1, Jun. 8, 2023
Int. Cl. G01R 31/396 (2019.01); G01R 31/388 (2019.01); G01R 31/389 (2019.01); H01M 10/28 (2006.01); H01M 10/42 (2006.01)
CPC G01R 31/396 (2019.01) [G01R 31/388 (2019.01); G01R 31/389 (2019.01); H01M 10/28 (2013.01); H01M 10/4207 (2013.01); H01M 10/4242 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method for improving the operational efficiency of a battery pack having at least two nickel metal hydride, NiMH, battery modules, each battery module having at least one battery cell, each battery module having a casing that encompasses the at least one battery cell and encloses a gas space, the gas spaces of the battery modules being connected to each other to form a common gas space, each battery cell having a first electrode, a second electrode, a porous separator, and an aqueous alkaline electrolyte arranged between the first electrode and the second electrode, the porous separator, the first electrode, and the second electrode being configured to allow exchange of hydrogen and oxygen by allowing gas to migrate between the electrodes, and at least one of the casings having a gas inlet for adding a gas or a liquid to the common gas space; the method comprising:
obtaining data on the battery modules, wherein the data relates to the number of battery cells per battery module and the number of battery modules, temperature of each battery module, and the energy capacity of the battery modules;
obtaining an internal resistance (Ri1, Ri2, Ri3) for at least two of the battery modules;
determining, in case a difference in the internal resistance between any of the battery modules exceeds a predetermined first resistance threshold (Rt1), based on the internal resistance and the data on the battery module, a filling amount of oxygen to be filled into the battery module in order to reduce the difference in the internal resistance between any two battery modules to a level below the predetermined first resistance threshold (Rt1);
initiating filling of the battery pack based on the determined filling amount of oxygen; and
filling the battery pack with the determined filling amount of oxygen.