An apparatus for effecting power distribution to a host system at a supply locus from one of a voltage source or a battery includes: (a) a current transfer unit having a first and a second connection; the second connection being coupled with the battery; and (b) a control device switchingly coupling the first connection to effect alternating connection with the voltage source and with a low potential. The control device is sensingly coupled with the voltage source and within the apparatus for receiving indicating signals. The control device responds to the indicating signals to control the alternating connection to achieve stepped up delivery of voltage presented by the battery unit to the supply locus when the indicating signals indicate a first circumstance. The control device responds to the indicating signals to switchingly control the alternating connection to achieve charging the battery when the indicating signals indicate a second circumstance.