Cell phones run on batteries that are recharged through connection to an electrical socket when they are drained of power. Cell phone batteries are square, flat, installed in the back of the device and covered by a protective cover. Since cell phones are left on for most of the day, the battery is in almost constant use. Cell phone batteries do not last forever and it is important to identify the warning signs that indicate a battery needs to be replaced. Step 1 Determine the purchase date of the cell phone or the installation date of the battery. Cell phone batteries only last between one to two years, which equates to approximately 300 to 500 charging cycles. If the phone battery is older than two years, it should be replaced. Step 2 Turn the phone off and place it into the charger or insert the charger connector into the cell phone. Allow the cell phone to charge for the amount of time recommended by the manufacturer. The average charging time is usually between four to six hours. Step 3 Remove the cell phone from the charger and immediately turn it on by pressing the phone's power button. Step 4 Wait until the phone come on and then check the battery level icon located on the cell phone's main display panel. If the battery level is lower than full, it indicates that the battery is not fully charged. This means that the battery is getting old and the level of charge it holds will continue to decrease. Replace the battery as soon as possible. Step 5 Use the phone as normal and pay attention to the battery level. If the phone dies within a few hours, or the battery level drops rapidly, this is a sign that the batteryshould be replaced. Related product recommendation