|OddMix ELECTRONICS - BATTERIES|
Batteries Primary Secondary Galvanic Chemical Cells Voltaic Electrolytic Information
|Fig 1. Two Modified Leclanche Cell 3V Primary Battery|
Batteries are one of the most common components produced in the industrial world. They are a class of components that are commonly used to supply electric power for portable devices. Many times they no way around using them as no other power supply is available. Archeological evidence - like the Baghdad battery and richly electroplated jewelry items - suggests that batteries were known and used, possibly for electroplating in ancient times
The Leclanche type single fluid, primary cell survived relatively unchanged since its invention in 1868. All dry cells are descendents to the original wet cell. Dry cells are not dry. Instead of the liquid electrolyte, dry cells have their electrolyte in a gel or paste form. It increases the cell resistance, but makes it possible to have portable cells for flashlights, radios, and other items.
|Fig 2. Sixty Modified Leclanche Cell 90 Volt Primary Anode Battery|
An electrochemical cell converts chemical energy to electrical energy. Each type of cell has a unique open circuit voltage. The value of this voltage that is always small is solely dependent of the chemical composition of the cell. Cells of the same chemical composition have the same open voltage regardless of their physical size. Larger size cells however can provide larger current then smaller ones. A cell is an elementary component of a battery. When more than one cell is connected together they are called a battery.
|Fig 3. Six Ni-Cd Cell 7.2V Secondary Battery|
Batteries, or multiple cells, can be classified as primary or secondary types. The primary battery types are further divided as disposable, like dry cells, or permanent like fuel cells. The secondary cells are generally rechargeable. Because of the secondary cells store or accumulate the electric charge when connected to charging circuits, in European literature, they often referred to as accumulators. In American literature lead acid batteries often called storage cells.
Two major secondary cell types are used most often. The lead acid battery is standard equipment in most automobiles around the world. The other popular type, frequently used cell is the alkali electrolyte based Nickel Cadmium or Ni-Cd. It is an improved version of the nickel ferrite or Ni-Fe cell, which was invented by Thomas A. Edison.
New primary and secondary cells are continually under development and some are actually currently in production. Of these new types, the lithium and lithium-ion cells are the most notables. They have higher energy density, open circuit voltage, low weight for their energy density and exceptionally long storage time. Presently their cost is the limiting factor of their use.
The power density of present day primary cells and batteries are still very limited, and their power is the least economical to use of all available power sources.