uses nickel oxide in its positive electrode (cathode), a cadmium compound in its negative electrode (anode), and potassium hydroxide solution in its electrolyte. This is rechargeable, so you can use it over and over.

NiCd batteries typically last longer, in terms of number of charge/discharge cycles, than other rechargeable batteries such as lead/acid batteries.

A battery charger is a device used to put energy into a secondary cell or (rechargeable) battery by forcing an electric current through it.

The purchase of a charger is cheap and simple. They are so foolproof these days that even if you get the polarity wrong, you won't get a spark, and the charger will not be damaged.

a high energy density, 3.6V battery that is widely used in the portable equipment market. It uses lithium metallic oxide in its positive electrode (cathode) and carbon material in its negative electrode (anode), and the lithium ions inside the battery transfer between the positive electrode and the negative electrode during charge or discharge.

Features:
- High voltage of 3.6V lets you cut down on the number of batteries you use.
- High energy density minimizes battery size and weight, making it perfect for use in small portable equipment.
- No metallic lithium is used so charging and discharging are very safe.
- No memory accumulation so it provides a full charge every time.
- The outer casing in square type batteries is an aluminum alloy, so overall battery weight is lower.

a secondary battery which lasts more than twice as long as CADNICA batteries. Twicell uses hydrogen absorbing alloys in its negative electrode (anode) and nickel oxide in its positive electrode (cathode). Since its release, the first in the world in October 1990, the "Twicell" sealed Nickel-Metal Hydride battery has developed a strong reputation for high capacity, high performance and high quality. In November 1996, Sanyo was the first manufacturer in the world to achieve 300 million cells accumulatively.

The HR-4/3AU (3,500mAh) is a new battery (volumetric energy density: 300Wh/l), first marketed in May 1996, that well exceeds the volumetric energy density of lithium-ion batteries. Sanyo released another Twicell battery of even higher capacity (volumetric energy density: 340Wh/l) in the end of 1997. In addition, the new Twicell HR-4/3FAU(4,000mAh), released in September 1996, was specially designed for notebook computers and has the same diameter (18mm) as the lithium-ion UR18650 battery.