Patent ID: 7710120

Claim:
An abnormal voltage detector apparatus for use in an assembled battery comprising a plurality of battery blocks connected in series to each other, said abnormal voltage detector apparatus detecting voltage abnormality in said assembled battery, each battery block comprising at least one secondary battery, said abnormal voltage detector apparatus comprising: a detecting part for detecting whether or not each of said battery blocks is in a voltage abnormality state by comparing either one of a voltage of said each battery block and each battery measuring voltage, which is a voltage lowered from the voltage of said each battery block, with a predetermined reference voltage, for generating each of abnormality detecting signals containing information about a detected result, for calculating a time ratio of a time interval, for which said assembled battery is in a voltage abnormality state, to a predetermined time interval, based on the abnormality detecting signals, and for detecting a voltage abnormality of said assembled battery based on a calculated time ratio, wherein said detecting part includes: voltage changing circuits, each changing either one of each of the battery measuring voltages of said each battery block and the reference voltage; a signal generator for generating a serial signal including control signals for controlling an operation of each of said voltage changing circuits; a serial-parallel converter for converting the serial signal into parallel signals; and a level converter circuit for converting a voltage level of each of voltage levels of at least one of the control signals of the parallel signals into each of converted voltage levels thereof, which is a voltage level of said each battery block, respectively, by utilizing voltage differences each between electrodes of each transistor, and for outputting the parallel signals having converted voltage levels to the voltage changing circuits as the control signals.