Abstract: The invention is directed to a self-powered lavage instrument used with an external fluid source for debridement of soft tissue. A housing includes at least two housing parts which are selectively attachable to and detachable from each other. A fluid nozzle is defined by or connected with the housing. A pump assembly is removably installed within the housing, and includes a case carrying an electric motor, a fluid pump and a plurality of power cells. The fluid pump is connected with the fluid nozzle and connectable with the external fluid source. The pump assembly further includes a plurality of clips, with each clip frictionally engaging and thereby electrically interconnecting two of the power cells.