A high voltage battery pack comprises series-connected battery units, each separately powering a respective DC/DC converter. The converter outputs are coupled in parallel to supply a low-voltage DC bus. A central module has 1) an outer loop controller generating a target current to regulate the bus voltage and 2) an allocator distributing the target current via allocated current commands for respective converters. Local controllers each regulate an output current of a respective converter. The allocator identifies battery units having a predetermined deviation from a reference metric that characterizes the battery pack, allocates reverse currents to respective converters for the identified battery units, and increases the target current commanded for the DC/DC converters not allocated to have a reverse current by the allocated reverse currents. Battery units with extremely low or high states as compared with the other units are quickly balanced, thereby improving overall performance of the battery pack.