Also known as: Power Cell
Battery is the normal power source used to operate a mobile phone. The battery capacity is usually measured in units of mAh (milliamps x hours), which is the electric current output that the battery can produce over a specified time. The higher the mAh rating of the battery the longer it will be able to power the phone. Mobile phone batteries are often available in "standard" or "extended" versions, the latter having a larger capacity to power the phone for a longer period of time.
Several types of battery have been used in mobile phones, the main types being: Nickel Cadmium (NiCd), Nickel Metal Hydride (NiMH), Lithium Ion (Li-Ion) and Lithium Polymer (Li-Po). NiCd and NiMH (to a lesser degree) suffer from memory effect.
All batteries slowly lose their charge with time, even when unused. The rate at which batteries self-discharge will depend on their type, and it is found that an unused Li-Ion battery is the best at holding its charge, a NiMH battery the worst, and NiCd is somewhere in between