As the counterparts of alternators, the auxiliary power modules (APM) in electric vehicles (EVs) play an irreplaceable role in bridging the high-voltage (HV) propulsion system and low-voltage (LV) auxiliary system. With the increasing demands on fast charging, the HV propulsion system is seeing an involution from 400 V system to 800 V system. To adapt to the trends, the APM also faces the challenge of accepting a wider input voltage range, particularly in EVs with a reconfigurable battery pack. This paper proposed a reconfigurable current-fed dual active bridges (CFDAB) based converter which accepts an ultra-wide-range input from 180V to 900V and an output from 6V to 16V to cover both 400 V and 800 V systems. Topology, operation principles, and simple control to minimize the switching loss are discussed in the paper. A >3 kW prototype with a peak efficiency of 97% was built and tested, which successfully validated the proposed topology and control.