A rechargeable battery. Has a nickel cathode and a cadmium anode. Relatively expensive because of the scarcity of cadium.

The typical ni-cad provides about 1.25 volts. Stable in storage (holds charge well) so often used in emergency systems.

NiCd, short for, Nickel Cadmium is a very popular type of rechargeable battery, mainly due to its cheap cost. Newer types of batteries such as NiMH and Li-Ion have higher energy density and are becoming comparable in price to the Ni-Cad battery.


The Nickel cadmium accumulator was a improvement of the nickel iron accumulator and was developed in 1932, but wasn't put into common use before the 1960's. It consists of a positive electrode of nickel foil and a negative of cadmium. Between the electrodes a porous plastic layer soaked with an potassium hydroxide electrolyte. This assembly is rolled up and put inside a metal or plastic container. The foil buildup is used to get a high surface area.

The NiCd accumulator is usually charged by a constant current charging circuit. A standard charger uses a current of 0.1C, this means 0.1 x cell capacity (a 1 Ah battery would be charged with about 0.1A). Usual charging time is 14-16 hours.

A rapid charger uses between 0.5C and 1.5C, but this type of charger must monitor the battery to prevent overcharging. Since the battery temperature rises rapidly when the cell is fully charged, this is usually done with a temperature sensor that cuttes off the charging current when the temperature reaches 45°C.

In stand-by applications the battery is constantly charged at 0.05C. This type is used in backup power for memory and clock circuits.

The NiCd cell can supply up to 100C(100x capacity) for short periods, but constant discharge should not be higher than about 10C. The NiCd cell has a selfdischarge of about 0.041%/h.

The NiCd accumulator is one of the most used rechargeable batteries, but since it contains the highly toxic element cadmium it is in the process of being replaced with the NiMH accumulator.

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