THE NICKEL CADMIUM (NiCd) BATTERY


Alkaline nickel battery technology originated in 1899 when Waldmar Jungner invented the nickel cadmium battery. The materials were expensive compared to other battery types then available and its use was limited to special applications. In 1932, the active materials were deposited inside a porous nickel-plated electrode and in 1947 research began on a sealed NiCd battery that recombined the internal gases generated during charge rather than venting them. These advances led to the modern sealed NiCd battery which is in use today.

Among the rechargeable batteries, the NiCd remains a popular choice for applications such as portable radios, emergency medical equipment, professional video cameras, data loggers and power tools. Over 50% of all rechargeable batteries for portable equipment are NiCdís. The introduction of newer battery chemistries caused the use of the NiCd to drop slightly. However, recognition of the limitations on the alternative chemistries has led to renewed interest in the NiCd chemistry.

Some of the distinct advantages of the NiCd over other battery chemistries are:

Fast and simple charge.
High number of charge/discharge cycles (if properly maintained, the NiCd provides over one thousand charge/discharge cycles.)
Excellent load performance, even at cold temperatures (the NiCd can be recharged at low temperatures).
Simple storage and transportation (the NiCd is accepted by most air freight companies).
Easy to recharge after prolonged storage.
Forgiving if abused.
Economically priced.
Available in a wide range of sizes and performance options.

The NiCd is a strong and silent worker; hard labor poses no problem. It prefers fast charge over slow charge and pulse charge over DC charge. Improved performance is achieved by interspersing discharge pulses between charge pulses. Commonly referred to as burp or reverse load charge, this charge method promotes high surface area on the electrodes, resulting in enhanced performance and increased service life. Reverse load also improves fast-charging because it helps to recombine the gases generated during charge. The result is a cooler and more effective charge than with conventional DC chargers.

Another important purpose of reverse load is to minimize the crystalline formation for improved battery performance and prolonged service life. Research conducted in Germany has shown that reverse load adds 15% to the life of the NiCd battery.

The NiCd does not like to be pampered by sitting in chargers for days and being used only occasionally for brief periods. In fact, the NiCd is the only battery type that performs best if fully discharged periodically. All other chemistries prefer a shallow discharge. So important is a periodic full discharge that, if omitted, the NiCd gradually loses performance due to the formation of large crystals on the cell plates, also referred to as memory.

4.1 Memory: Myth or Fact?

Charging The NiCd Battery

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