Battery eliminator
Encyclopedia
A battery eliminator is a device powered by an electrical source other than a battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

, which then converts the source to a suitable DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...

 voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...

 that may be used by a second device designed to be powered by batteries.

A battery eliminator eliminates the need to replace batteries but may remove the advantage of portability. A battery eliminator is also effective in replacing obsolete battery designs.

Some examples of battery eliminators:
  • 9v mains power supply
    Power supply
    A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...

    , size and shape of a PP9 battery, intended to replace the battery in portable radios. 1960s
  • Solar panel providing power for a portable appliance

History

Early commercial battery eliminators were produced by Edward S. Rogers, Sr.
Edward S. Rogers, Sr.
Edward Samuel "Ted" Rogers is regarded as the founder of Rogers Communications although it was established in 1967, almost three decades after his death.-Life and career:...

 company in 1925, as a complement to his line of "batteryless" radio receiver
Receiver (radio)
A radio receiver converts signals from a radio antenna to a usable form. It uses electronic filters to separate a wanted radio frequency signal from all other signals, the electronic amplifier increases the level suitable for further processing, and finally recovers the desired information through...

s. Another early producer of battery eliminators was the Galvin Manufacturing Corporation (later known as Motorola
Motorola
Motorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...

) which was opened on September 25, 1928 by Paul Galvin and his brother Joseph E. Galvin, to build battery eliminators for radio receivers installed in automobiles.

While it might seem surprising to use such a device in a car to power a radio, the first car radio
Car audio
Car audio/video , auto radio, mobile audio, 12-volt and other terms are used to describe the sound or video system fitted in an automobile. While 12-volt audio and video systems are also used, marketed, or manufactured for marine, aviation, and buses, this article focuses on cars as the most common...

 receivers were based on vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

 technology which required two or three different voltages to function:
  • LT, typically 4 or 6.3 volts at high current to power the filaments
  • HT, typically 100 to 300 volts at low current to power the anode
    Anode
    An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....

     circuitry
  • Additional voltages were sometimes also required for grid bias
    Grid bias
    Grid bias is a DC voltage applied to electron tubes with three electrodes or more, such as triodes. The control grid of these devices is used to control the electron flow from the heated cathode to the positively charged anode...

    .


Batteries designed for these portable vacuum tube receivers were a combination of several different battery types and sizes, combined in a single package and intended to slowly wear out at about the same rate. The battery typically connected to the radio via a specially shaped four- or five-pin connector, keyed so that the plug must be inserted correctly.

A battery eliminator would take the typical 6-volt or 12-volt DC power from a car battery and transform it into the required LT and HT needed to power the vacuum tubes in a car radio.

Without a battery eliminator, it was necessary to occasionally replace the battery pack
Battery pack
A battery pack is a set of any number of identical batteries or individual battery cells. They may be configured in a series, parallel or a mixture of both to deliver the desired voltage, capacity, or power density...

in the vacuum-tube car radio.
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