Abstract: A so-called sea water battery is disclosed which has a battery cell system with electrode plates, preferably magnesium and silver chloride plates, and using as electrolyte a solution of chemicals introduced from the outside into its cell system. According to a particular charcteristic of the invention, the pipe or duct by which water is supplied into the cells contains an ejector mechanism drawing from a particular tank a solution of chemicals and admixing this solution with the feed water. The chemicals thus introduced into the battery serve one or several of the following purposes: to increase the conductivity of the electrolyte; to counteract excessively vigorous dissolution of the electrode materials; and to improve the efficiency of the electrolyte.According to an optional characteristic of the invention, the chemicals to be introduced as has been said are provided in said particular tank in solid form, and water is passed through said tank to solve them and to carry them off.