Patent ID: 8154253

Claim:
A cell voltage abnormality detector for a multi-cell series battery made up of plural battery cells connected in series that is used to detect cell voltage abnormalities in at least a single cell of the multi-cell series battery comprising: a selection switch for selecting any of the at least single cells of said multi-cell series battery and retrieving cell voltage from between first and second monitoring terminals; a cell voltage/monitoring current converter, which has a first transistor connected between said first and second monitoring terminals and which converts the voltage of said battery cell selected by said selection switch into a monitoring current; a monitoring current/monitoring voltage converter, which has a second transistor that, in combination with said first transistor, forms a current mirror circuit, and which converts the monitoring current generated by said cell voltage/monitoring current converter into a monitoring voltage; and a comparison/evaluation circuit, which compares said monitoring voltage obtained by said monitoring current/monitoring voltage converter with a prescribed reference voltage and which determines whether the voltage of said battery cell selected by said selection switch is outside of a predetermined normal range.