Patent ID: 8054044

Claim:
An apparatus for balancing charge capacity of a battery cell, comprising: a voltage sensing and discharging circuit including a battery having a cell group, a switching unit for selectively connecting both terminals of each battery cell of the cell group to first and second conductive lines, a capacitor connected to the first and second conductive lines in parallel, a voltage amplifying unit connected to both terminals of the capacitor via a first switch, and a discharge resistance connected to both terminals of the capacitor in series via a second switch; and a voltage balancing unit for subsequently controlling the switching unit to connect both terminals of each battery cell of the cell group to the first and second conductive lines to charge the capacitor with a voltage of each battery cell, controlling the first switch to turn on to sense a charged voltage of the charged capacitor so that the voltage of each battery cell is sensed after disconnecting each battery cell from the first and second conductive lines, then selectively controlling the switching unit to connect both terminals of a battery cell that needs balancing of charge capacity to the first and second conductive lines to charge the capacitor with a voltage of the battery cell that needs balancing of charge capacity, and controlling the second switch to turn on to discharge the charged voltage of the corresponding capacitor by means of the discharge resistance after disconnecting the battery cell that needs balancing of charge capacity from the first and second conductive line so that the charge capacity of the battery is balanced, wherein the battery cell that needs balancing of charge capacity has a voltage a predetermined limit higher than a minimum voltage level.