Patent ID: 8154257

Claim:
A storage system, comprising: a power source; a plurality of battery modules each having a battery configured to be charged with power supplied by the power source; a controller that controls access with respect to a plurality of physical storage devices each provided with a volatile memory that receives a power supply from the power source if any, and if not, receives a power supply from the battery of at least any one of the plurality of battery modules; and a charge control unit that, upon receiving a charging command for any of the battery modules, detects a quantity of the battery modules that are undergoing charging, and wherein the charge control unit initiates charging of the battery in any battery module for which a charging command is received upon detecting that the quantity of the battery modules that are undergoing charging is less than a predetermined number, and the charge control unit, upon detecting that the predetermined number of the plurality of battery modules are undergoing battery charging, stops charging of the battery in any remaining of the battery modules.