A multiple-use battery pack system includes a battery pack housing enclosing a lead-acid battery and a post portion projecting from the housing and adapted to be plugged into a cavity in an associated cordless power hand tool. First terminals on the post portion connect the battery to the tool circuitry when the post portion is plugged into the tool. When used for powering other loads, the post portion is plugged into a receptacle in an adapter housing, in which position either the first terminals or, alternatively, second terminals on the battery pack housing connect the battery to jumper cables on the adapter housing. Latch mechanisms on the battery pack housing cooperate with keepers on the associated hand tool for latching the battery pack in place thereon.