The batteries that most people used in their homes from the 1930s through the 1950s were the familiar C or D cells that we still sometimes use for flashlights-in fact we still call these “flashlight batteries.” These batteries have to be changed often, and if “dead,” can leak chemicals. Fortunately, most homes got central station electric power by around 1940, but portable radios continued to rely on batteries. That is very high voltage compared to today’s radios, which need only a 9-volt battery to operate. Later, in the 1930s, engineers designed more efficient radios that used much smaller dry cell batteries, but these still had to supply up to 90 volts or more to operate the radios’ vacuum tube circuits. Two of these batteries could be small dry cells, but one of them was usually a large, acid-filled battery that could ruin furniture and carpets if it was knocked over. These were usually designated as the “A,” “B,” and “C” batteries. Many early radios required two or three batteries of different voltages to supply various circuits. Most homes in the 1920s still did not have electric service, so it was necessary to use batteries to power a radio. The next big boost for the battery was the invention of radio broadcasting in the 1920s. Today’s automobiles carry with them a small electric generating system that partially reverses the chemical processes in the battery which are responsible for generating electricity, and the effect is to "recharge" the battery while the engine is running. As in other batteries, the chemical reaction between the metal and the chemicals that are dissolved in the liquid creates a source of usable electricity. Inside a sturdy box are heavy lead plates, separated by a liquid acid solution. In many ways, most auto batteries still resemble the lead-acid batteries that powered most electric cars in the early 1900s. Today, the battery is an essential part of every automobile. It was not used to power the car itself, but to operate the starter and to supply energy to the ignition systems of the rapidly evolving gasoline automobile. But the battery did become a permanent feature of every automobile. Edison’s work on batteries advanced the state of the art, but electric cars never achieved much success, and in fact almost disappeared by 1930. At that time, the superiority of the gasoline automobile had not yet been demonstrated, and there were many electric cars on the market. Thomas Edison worked on smaller, "alkaline" batteries (based on nickel and iron) in the early 1900s, because he believed they could be excellent sources of power for electric cars. At the telephone central station, where switchboard operators worked, large banks of acid-filled batteries supplied current to all the telephones in the area.Īfter 1900 automobile designers also began demanding better batteries. That’s why telephones usually continue to work during bad weather, when the lights go out. The batteries are located in the telephone company’s central offices and the electricity is carried to your home on the telephone wires. Most telephone systems, even today, supply power directly to the telephone from batteries rather than relying on commercial electric power lines. Large, rechargeable batteries were developed to supply the needs of the telephone system after the 1880s. The telephone, invented in the 1870s, also needed batteries and the success of the telephone system led to more battery research. The small 9-volt batteries used today are a good example of this. Dry cells can be stacked inside a single container to produce batteries with other voltages. A single dry cell produces about 1.5 volts. A carbon rod is inserted into the paste and conducts electrons to the outside of the cell, where wires or metal contacts carry the electrons that power the device. The interaction of the paste and the zinc creates a source of electrons. It holds a moist paste inside a zinc container. The dry cell is not completely dry, but it seems dry in comparison to the voltaic pile. After many years of experimentation, the “ dry cell” was invented in the 1860s for use with the telegraph. The salt bridge consists of a concentrated, nonreactive, electrolyte solution such as the sodium nitrate (NaNO 3) solution used in this example.The pile or battery remained a laboratory curiosity for years, until the newly invented telegraph and telephone created a demand for reliable electrical power.
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