<P> The dry cell form was used to power early telephones--usually from an adjacent wooden box affixed to the wall--before telephones could draw power from the telephone line itself . The Leclanché cell could not provide a sustained current for very long . In lengthy conversations, the battery would run down, rendering the conversation inaudible . This was because certain chemical reactions in the cell increased the internal resistance and, thus, lowered the voltage . These reactions reversed themselves when the battery was left idle, so it was good only for intermittent use . </P> <P> Many experimenters tried to immobilize the electrolyte of an electrochemical cell to make it more convenient to use . The Zamboni pile of 1812 was a high - voltage dry battery but capable of delivering only minute currents . Various experiments were made with cellulose, sawdust, spun glass, asbestos fibers, and gelatine . </P> <P> In 1886, Carl Gassner obtained a German patent on a variant of the Leclanché cell, which came to be known as the dry cell because it did not have a free liquid electrolyte . Instead, the ammonium chloride was mixed with plaster of Paris to create a paste, with a small amount of zinc chloride added in to extend the shelf life . The manganese dioxide cathode was dipped in this paste, and both were sealed in a zinc shell, which also acted as the anode . In November 1887, he obtained U.S. Patent 373,064 for the same device . </P> <P> Unlike previous wet cells, Gassner's dry cell was more solid, did not require maintenance, did not spill, and could be used in any orientation . It provided a potential of 1.5 volts . The first mass - produced model was the Columbia dry cell, first marketed by the National Carbon Company in 1896 . The NCC improved Gassner's model by replacing the plaster of Paris with coiled cardboard, an innovation that left more space for the cathode and made the battery easier to assemble . It was the first convenient battery for the masses and made portable electrical devices practical, and led directly to the invention of the flashlight . </P>

When was the first dry cell battery invented