Abstract: A back-up power supply includes a fixed charger fixably mounted in an enclosure of a computer system and having a charging circuit electrically coupled to the computer system. The charger is mounted in a case which houses the charging circuit and provides EMC shielding. A removable battery pack is docked with the charger through cooperative blind docking connectors to electrically couple a pair of batteries with the charging circuit. The batteries are enclosed within a case to substantially restrict external access to the batteries. Preferably, the batteries together form an "L" shape, and the charging circuit is disposed on a circuit board having low and high profile areas. The batteries in the battery pack are disposed adjacent the low profile areas of the circuit board, such that the overall space required for the power supply is reduced.