Patent ID: 6400124
Filing Date: 2002-06-04
Classification: H02J

Abstract:
A battery charger for charging a plurality of battery cells connected in series with one another with a constant current in a batch manner, said battery charger including a plurality of cell shunt circuit sections connected in parallel with the battery cells, respectively, a plurality of cell voltage detecting sections for detecting cell voltages of said battery cells, respectively, and a cell shunt driving unit for driving said cell shunt circuit sections, respectively,each of said cell shunt circuit sections comprising: an energy reservoir acting as a bypass path for bypassing a charging current supplied to a corresponding one of said battery cells so as to be input to the following battery cell provided at a downstream side of said one battery cell so as to reserve surplus energy obtained from the charging current thus bypassed and regenerate the thus reserved surplus energy to a batch charging line connected with said serially connected battery cells; and a switching element inserted in said bypass path for opening and closing thereof; wherein said cell shunt driving unit compares a voltage detected by each of said cell voltage detecting section with a reference voltage, and outputs to said switching element of each of said cell shunt circuit sections a drive pulse signal of a pulse width corresponding to a difference between said detected voltage and said reference voltage, and wherein said energy reservoir regenerates said surplus energy to said batch charging line when said switching element opens said bypass path based on said drive pulse signal from said cell shunt driving unit.