I have an outboard, but it does have a generator - max six amps.

The Rule pump is rated 20 amps ( I don't think it draws that much). With an 80 ampere hour battery, that means the pump could run for four hours, or long enough to drain Lake Mead, if my calculations and understanding of ampere hours is correct. Each spring I fill up the bilge above the floor to clean out the beer from broken cans the previous summer. The pump (with automatic shut off) takes perhaps a minute - at the outside - although I have never timed it (1 1/2" hosing leading ouside through the bottom in the motor well/lazarette.)

My exterior Whale Gusher is flush mounted on the port side of the cockpit bench, aft of the bench cover, on the vertical face, just in front of the back end of the cockpit (about where the tiller post is). It is mounted high on the vertical lazarette wall. I keep the handle just inside the motor lazarette opening panel. The retainer string for the handle is long enough so I can take it out of the brackets in the motor well and insert it into the pump. Hope this all makes sense.