Patent ID: 8829854

Claim:
A secondary battery which includes a plurality of battery cells and measures voltages of the battery cells, the secondary battery comprising: a capacitive device connected to the battery cells to sequentially store the voltages of the battery cells; a relay between the battery cells and the capacitive device, sequentially connecting the battery cells to the capacitive device; an A/D converter connected to the capacitive device to receive and convert the voltages of the battery cells; a reference voltage source; and a switching device serially connected to the reference voltage source when the relay sequentially connects the battery cells to the capacitive device, the reference voltage source and the switching device being connected to ends of the capacitive device, and wherein the switching device is turned on before the voltage of each of the battery cells is applied to the capacitive device, to thereby store a reference voltage of the reference voltage source in the capacitive device, the reference voltage added to each of the voltages of the battery cells.