Abstract: Alkaline electrolyte electric primary cell comprising a visual indicator of its state of charge, the said primary cell having a negative electrode basically containing zinc powder in contact with its outside casing. The said charge indicator is constituted by a perforated copper or copper alloy sheet which is visible from the outside of the primary cell and is in contact with the negative mass. On assembly, the copper sheet becomes coated with a film of zinc and appears to have a grey color. During cell discharge the zinc of this film oxidizes and the original coloration of the sheet comes visible through a transparency provided in at least a portion of the casing. The sheet may be located at any selected depth in the thickness of the negative electrode and the time of restoration of original coloration is a function of the location depth and thus indicative of the residual state of charge.