STORAGE BATTERY SYSTEM AND MODIFICATION METHOD OF CONNECTION CONFIGURATION

PROBLEM TO BE SOLVED: To provide a storage battery system deterioration in the capacity of which can be suppressed while ensuring a long life, and to provide a modification method of a connection configuration.SOLUTION: An abnormality detection device of an embodiment includes a battery cell group consisting of a parallel connection of a plurality of battery cell arrays each consisting of a series connection of a plurality of battery cells, a first connection unit for connecting different battery cells included in different battery cell arrays of the battery cell group replaceably, an estimation unit for estimating the deteriorated state of a battery cell, a determination unit for determining whether or not replacement of the battery cell is required, a calculation unit which calculates an evaluation value for evaluating the sound state of the battery cell array, and a control unit for controlling the first connection unit being connected with a deteriorated battery cell, determined to be replaced by the determination unit, in such a direction that the evaluation value goes above a predetermined threshold, and replacing the deteriorated battery cell by a different battery cell.