Patent ID: 8643376

Claim:
A voltage measuring apparatus for measuring an output voltage of an assembled battery in which a plurality of unit cells are connected in series and are divided into a plurality of blocks, the voltage measuring apparatus comprising: a block voltage detection unit which detects a voltage of at least one of the plurality of blocks; a sampling voltage generation unit which is provided in the block voltage detection unit and generates an analog sampling voltage applied in the sampling voltage generation unit; an A/D conversion unit which is provided in the block voltage detection unit and digitizes the analog sampling voltage to output a digital sampling voltage for each of the plurality of blocks; and a voltage variation detection unit which obtains an error ratio of the voltage detected by the block voltage detection unit for each of the plurality of blocks, wherein the error ratio is obtained based on the digital sampling voltage for each of the plurality of blocks, wherein the voltage variation detection unit calculates one average value of the digital sampling voltages from the plurality of blocks and obtains the error ratio for each of the plurality of blocks based on the average value set as a reference value and the digital sampling voltage for each of the plurality of blocks.