A primary electrochemical cell operative to provide a warning indication toward the end of discharge of the cell signalling an approaching end-of-life of the cell. The cell includes a tubular porous carbon cathode structure disposed within a metal housing of the cell together with an anode structure and an electrolytic solution.The anode structure includes first and second electrochemically active elements, for example, lithium and calcium, having different oxidation potentials within the cell and consumable by electrochemical action within the cell during discharge of the cell. The consumption of the active elements during discharge of the cell results in the establishment of different and distinguishable operating voltages for the cell. The active elements are arranged with respect to each other such that the active element of higher oxidation potential (i.e., the lithium) is consumed prior to the other active element (i.e., the calcium). The change in value of the operating voltage of the cell due to successive consumptions of the two active elements is detected to provide a warning indication signalling the approaching end-of-life of the cell.