SECONDARY BATTERY SYSTEM AND SECONDARY BATTERY CONTROL METHOD

A secondary battery system is a secondary battery system including a battery bank including a battery rack including a plurality of battery cells connected in series and a power converter for charging and discharging a power system by one or a plurality of the battery racks connected in parallel, the secondary battery system includes a switch that enables the battery rack included in the battery bank to be switched to a power converter of another battery bank; and a controller that monitors a deterioration rate or an age of use of the battery rack and controls the power converter and the switch, in which the controller instructs the switch about a power converter to be connected based on the deterioration rate or the age of use of the battery rack.