Abstract: The present invention is directed to any electrochemical cell casing design having an electrolyte fill aperture. The electrolyte fill aperture receives and directs the electrolyte into the casing. A fill plug has at least two components—an insert section detachably connected to a placement unit. The placement unit allows a user to properly position the insert section into the electrolyte fill aperture. Once this is done, the placement unit is detached from the insert section. The insert section in then hermetically sealed to the casing. If desired, the fill plug can be used for filling the electrolyte in the casing.