cathode of silver chloride or cuprous chloride. When activated by water, they rapidly build up voltages of 1.3 to 1.8 volts and operate at a constant potential between −55 and 95 °C (−67 and 200 °F).
Cuprous chloride, CuCl, can be prepared by treating metallic copper and cuprous oxide with hydrochloric acid or by treating metallic copper and cupric chloride with hydrochloric acid.