BATTERY DIAGNOSIS METHOD AND BATTERY SYSTEM APPLYING THE SAME

The battery diagnosis method includes calculating, by a battery management system (BMS), a plurality of direct current internal resistances (DCIRs) respectively with respect to a plurality of battery cells based on a plurality of cell voltages and a plurality of cell currents respectively with respect to a plurality of battery cells connected in parallel, deriving, by the BMS, an entire representative value of the plurality of DCIRs based on the plurality of DCIRs, calculating, by the BMS, a multi-parallel ideality factor based on a parallel connection number which is a number of the plurality of battery cells connected in parallel, calculating, by the BMS, a dispersion of the DCIRs based on the plurality of DCIRs and the entire representative values of the DCIRs, calculating, by the BMS, an upper limit threshold value of a normal range based on the entire representative value of the DCIRs, the multi-parallel ideality factor, and the dispersion of the DCIRs, and deriving, by the BMS, the normal range based on the upper limit threshold value, and diagnosing a state of a battery pack including the plurality of battery cells according to the normal range.