STORAGE BATTERY

According to a storage battery of an embodiment includes a first battery module and a second battery module connected in parallel with the first battery module. The number of first cells connected in series in the first battery module is M, and the number of second cells connected in series in the second battery module is N. When an open circuit voltage at SOC=X % of the first cells and the second cells are Va1 (X) and Va2 (X), respectively, the voltages of the battery modules are M×Va1 (X)N×Va2 (X) in the range where the SOC of the cell is 70% to 100%.