BATTERY PACK AND METHOD OF CONTROLLING THE SAME

A battery pack includes: a pair of external terminals; a pair of first connection terminals; a first battery comprising a plurality of first battery strings connected in parallel between the pair of first connection terminals, each of the plurality of first battery strings comprising a plurality of first battery cells connected in series; an extended battery module comprising a pair of second connection terminals detachably connected to the pair of first connection terminals, and a second battery comprising a plurality of second battery strings connected in parallel between the pair of second connection terminals; and a battery management system (BMS) configured to determine a current protection level based on a total number of the plurality of first battery strings and the plurality of second battery strings, in response to the extended battery module being connected to the pair of first connection terminals.