Abstract: 1. A reserve battery comprising a cell, spaced electrodes in said cell, a lling aperture in said cell, a frangible sealed ampule containing electrolyte, a plunger adjacent said ampule, a conduit between said ampule and said cell aperture, a body of sealing material, and means for moving said plunger into contact with said ampule to crush same and force electrolyte through said conduit and aperture into said cell, said means being so constructed and arranged that upon further motion of said plunger the body of sealing material is disposed across the aperture to seal same.