A hand-held, battery powered liquid applicator having an on-board reservoir. An electric motor drives a piston in the reservoir via a pinion gear member and rack gear. A gear shifter may disengage the pinion gear member from the rack gear. A battery compartment may have a door has recess to enable a user to grasp a dry cell located farthest from the door. The rack gear may have modified profile teeth at the end of travel to allow the pinion gear member to slip when the piston is urged past the end of travel. The piston may have a length substantially equal to a characteristic length of the reservoir. Liquid may be drawn into the reservoir by powered or manual retraction of the piston and liquid may be delivered from the reservoir to an applicator head by powered or manual motion of the piston into the reservoir.