Photoflash battery

A photoflash battery is a specialized zinc-carbon battery optimized to provide a high electric current output for a short duration of time, such as required to fire a flashbulb. Service life for this battery in flashlight service is short, since flashlights required a lower but continuous long duration current.

Photoflash cells were in production during the flashbulb era, and were slowly phased out as alkaline cells came into general usage. The photoflash cell was produced as a 1.5 volt size D, C Size and AA Size.

The cathode (the material packed between the carbon rod and zinc shell) of a zinc-carbon cell is generally made of powdered carbon black (or acetylene black), manganese dioxide and electrolyte. The MnO2 to carbon ratios vary between 10:1 and 3:1 for general purpose cells. A 1:1 mixture is used for photoflash batteries. This allows a high current output with intermittent use, perfect for photoflash use. These cells have reduced capacity compared to those with a higher content of MnO2.[1]

Another common type of photoflash battery is a higher-voltage series assembly of cells, often totalling 22.5 volts, used in battery–capacitor flash units. The battery slowly charges a capacitor, which then is discharged through a flashbulb to provide the heavy pulse of current to set off the bulb. . Higher voltage photoflash batteries are also made to fire reusable xenon flash tubes. These tubes require a high voltage. Eveready battery manufactured a 240 volt battery for such use, the Eveready 491 (NEDA 729). Also offered by Eveready was a model 497 battery capable of 510 volts, with a tap at 180 volts.

See also

References
  1. David Linden, Thomas B. Reddy (ed). Handbook Of Batteries, 3rd Edition. McGraw-Hill, New York, 2002 ISBN 0-07-135978-8 Chapter 8.


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