The electrifying effect of radio was changing the World and nowhere was it more evident than in the United States. Radio was bringing everything into focus and the true spirit of Roaring Twenties or Jazz Age was being felt on all fronts by 1925. 

A big market was born. Another market opened up for batteries, battery chargers and battery eliminators. 

  Chevrolet Sedan equipped with radio 

Explanation: in terms of supplying power to a radio set, the “A” battery was that which powered the filaments of tubes. The current requirement was on the order of two or tree amperes at 5 Volt, a 6 Volt storage battery was generally used. This high current drain meant frequent charging of the storage battery. The owner had to purchassed a charger. The function of the “B” batteries was to supply the plate voltage to the tubes. Typically, ten to twenty milliamperes of current were drawn from a 90 to 180 Volt “B” battery pack, depending on the number and types of tubes in the set. These “B” batteries (also called dry batteries) would last anywhere from a few weeks to a few months before replacement was necessary.

The above discussion also applies to the early automobile radios, except that the “A” battery current was generally supplied by the automobile battery. 

 Ford T - 1925 

The “B” eliminator terminology was also used for a few years, and in the case of the car radio, it was in the form of a motor generator, or later, the vibrator power pack. This will be described more fully in a later section.