disclosed herein is an integrated direct - current based uninterrupted power supply system connected to an ac power input and a server or a computer , comprising : an ac adapter / charger unit for providing power the system and charging an energy storage unit ; the energy store unit for monitoring , controlling and powering the system , and communicating the powering & amp ; battery capacity status with the server or computer , and a dc - to - dc converter circuit for providing multiple dc voltage rails .