An electrified vehicle high voltage battery pack has series-connected battery units or cells combining to provide the high voltage. To power a low voltage bus (e.g., for low voltage accessories or charging a low voltage battery) in a balanced manner, a plurality of DC/DC converters each has an input coupled to a respective battery unit and the converters have respective outputs coupled in parallel to the low voltage bus. A first loop controller receives an actual bus voltage. The first controller generates a target current in response to the bus voltage adapted to regulate the actual bus voltage to a target voltage less than the high voltage. A second controller distributes the target current into a plurality of allocated current commands for respective converters according to respective states of charge of the battery units connected to the converters.