Patent ID: 8004238

Claim:
An apparatus for balancing a battery pack having an overdischarge prevention function, which balances a charging voltage of each battery cell of a battery pack that includes a plurality of battery cells, the apparatus comprising: a discharge resistor installed on a conductive line connected to both ends of a battery cell in parallel; a charge pump for pumping charges only when a balance control signal of a predetermined frequency is input thereto; a discharge switching unit for connecting the battery cell to the discharge resistor when a driving voltage of an effective voltage level is applied thereto such that the battery cell is discharged; and a voltage charging unit for charging the pumped charges to apply the charging voltage as the driving voltage of the discharge switching unit, further comprising a balance signal relay unit installed on a conductive line through which the balance control signal is applied to the charge pump, the balance signal relay unit periodically relaying high-level voltage signals and low-level voltage signals to the charge pump according to the balance control signal having a predetermined frequency output from a controller.