Lithium ion batteries are the power source of choice for cellphones. Lithium ion batteries are manufactured with a circuit that functions as a kind of fuel gauge. The circuit uses the battery voltage to estimate the "state-of-charge", that is, the amount of usable power remaining. Over time the circuit will become inaccurate and must be reset. Otherwise the cell phone may shut off unexpectedly even though readouts indicate the battery still has power remaining.
1. Use the lithium ion battery installed in the cell phone until the battery power is completely consumed. This will not harm the lithium ion battery because it comes with an internal "safety board".
2. Take the battery out of the cell phone and put it on a charger which...(continues)