Cell phones have changed the world. A person can remain in "touch" with people around the globe thanks to cell phone technology. Even though cell phone technology is just a few years old, cellular phones have penetrated all corners of the world.

Cell phones are now available in thousands of models. Cell phone battery is one of the most important cell phone accessories. The cellular phone battery life is one of the key factors users look at when purchasing a new cell phone.

A battery consists of a cathode, an anode and an electrolyte. The cathode is a metal oxide strip, the anode a metal strip that has a tendency to oxidize, and the electrolyte a conducting medium in which the anode and cathode are kept. When the anode and cathode are connected, the anode draws oxygen atoms thus generating electricity. Various types of batteries are available like alkaline batteries, lead acid batteries, lithium/manganese dioxide batteries, nickel metal hydride batteries (NiMH), Nickel cadmium (NiCd) batteries, lithium ion batteries etc. For mobile phones lithium ion (Li-Ion) batteries are predominantly used.

Lithium ion cell phone batteries are rechargeable batteries. They are much lighter than other batteries because they carry extremely high-density charges and are easier to store than NiMH batteries. They do not suffer from memory effect. Sony Corporation first introduced lithium ion batteries in 1991.

Memory effect is a strange phenomenonif a battery (usually nickel batteries) is repeatedly charged at partial discharge, the battery "forgets" that it has the capacity to discharge fully. Gradually the battery loses all capacity to fully recharge and has to be discarded. Li-Ion batteries also have a low self-discharge rate of approximately 5% compared to other batteries that are generally around 20-30%. However if mistreated Li-Ion batteries can be dangerous and have very short lives.

Some guidelines that can increase cell phone battery life are:

• Never discharge Li-Ion battery fully, recharge it at 40% capacity.
• Never store batteries above 60 deg Celsius.
• Do not keep batteries in moist places.
• Do not dispose off batteries in fire. They may catch fire or explode.
• Store in a cool places, this will increase their life considerably.

One of the disadvantages of Li-Ion cellular phone batteries is that they have a fixed shelf life of approximately 5 years. The capacity of the battery reduces about 20% every year. Hence it is a good idea to check the manufacture date on cell phone batteries before purchasing. Generally in cell phones, the batteries cannot be interchanged and cellular phone batteries are model specific.