A control system for a battery system is provided. The control system includes: an N-phase DC-DC converter including N single phase DC-DC converters (wherein N is a whole number greater than one); a first microcontroller configured to control a first fraction of the N single phase DC-DC converters; and a second microcontroller configured to control a second fraction of the N single phase DC-DC converters. The first and second microcontrollers are connected to each other via a data line. In a first operation mode, control operations of the first microcontroller and the second microcontroller are synchronized via the data line to commonly control the N single phase DC-DC converters, and in a second operation mode, the first microcontroller and the second microcontroller independently control the first fraction and the second fraction, respectively.