Patent ID: 8129997

Claim:
A battery cell voltage measuring apparatus, comprising: a plurality of floating capacitors provided corresponding to a plurality of cells contained in a battery pack; a first switch for connecting one terminal of each corresponding floating capacitor to one terminal of each corresponding cell in a charge mode or connecting a reference potential to the one terminal of the floating capacitor in a measuring mode; a second switch for connecting the other terminal of each corresponding floating capacitor to the other terminal of each corresponding cell in the charge mode or connecting a common cell voltage measuring line to the other terminal of the floating capacitor in the measuring mode; and a cell voltage detector for measuring a voltage of each cell by switching each of the first and second switches into the charge mode to charge the voltage of each cell on each corresponding floating capacitor and time-differentially switching each of the first and second switches into the measurement mode to apply the cell voltage charged on the floating capacitor between the reference potential and the common cell voltage measuring line such that the cell voltage has the same polarity.