Patent ID: 7859227

Claim:
A state-of-charge adjusting apparatus comprising: a voltage detecting means for detecting each voltage of a plurality of unit cells, the plurality of the unit cells consisting of secondary batteries connected in series; a discharge resistance connectable to at least one of the unit cells for discharging at least one of the unit cells; and a capacity equalizing means for controlling discharge of the plurality of the unit cells through the discharge resistance on the basis of a voltage of each unit cell detected by the voltage detecting means so that the voltage values of the plurality of the unit cells become uniform, wherein the capacity equalizing means includes: (a) a block extracting means which extracts a block consisting of a plurality of unit cells connected continuously to each other, said plurality of the unit cells each having a voltage higher than a target voltage; (b) a first equalizing discharge means which then connects both ends of said block extracted by the block extracting means to the discharge resistance so as to discharge said extracted block; (c) a unit cell extracting means which extracts a unit cell having a voltage higher than the target voltage after action of the first equalizing discharge means is finished; and (d) a second equalizing discharge means which then connects both ends of the unit cell extracted by the unit cell extracting means to the discharge resistance so as to discharge the extracted unit cell until the voltage of the extracted unit cell reaches the target voltage; wherein the capacity equalizing means further includes a first discharge control means which makes the block extracting means and the first equalizing discharge means act repeatedly in sequence when the block extracting means extracts the block, until no blocks having a voltage higher than the target voltage are present and makes the first equalizing discharge means finish to act when the block extracting means does not extract the block any more, and then, following the absence of blocks having a voltage higher than the target voltage, makes the unit cell extracting means and the second equalizing discharge means act repeatedly in sequence when the unit cell extracting means extracts the unit cell, until no unit cells having a voltage higher than the target voltage are present, and makes the second equalizing discharge means finish to act when the unit cell extracting means does not extract the unit cell anymore.