Patent ID: 7759903

Claim:
A battery voltage measurement circuit that measures a voltage between two electrodes of each unit battery in a battery assembly having a plurality of unit batteries which are connected in series, the battery voltage measurement circuit comprising: conversion units each provided respectively to each unit battery to convert a voltage between the two electrodes of each unit battery into respective predetermined physical quantities; a level shifting unit to convert the physical quantities converted by the conversion units into voltages relative to a lowest electric potential of the battery assembly, wherein the level shifting unit is directly connected to the lowest electric potential of the battery assembly; a measurement unit that processes and measures the physical quantities converted by the conversion units with respect to each of the unit batteries; and a power source, isolated from the battery assembly, to supply power to the conversion units; wherein the measurement unit sequentially outputs digital values corresponding to the converted voltages based on the lowest electric potential of the battery assembly with respect to the unit batteries; and wherein each conversion unit includes a voltage-current conversion unit that converts the voltage between the two electrodes of each unit battery into a corresponding magnitude of an electric current.