Lithium-ion sony VGP-BPS21 battery is divided into two phases: the first constant current charging, to close to constant charge termination voltage, which is a 800mAh capacity battery, the termination of charging voltage 4.2V. Batteries 800mA (charge rate of 1C) constant current charge, the beginning of the slope of the battery voltage to a larger step, when the battery voltage approaches 4.2V, the 4.2V constant voltage charging change, the current gradually decreased and the voltage changes little to the charge current reduced to 1/10C (about 80mA), the view that close to full, you can terminate the charge (some chargers to 1/10C start timer, over a certain time after the end of the charge). Lithium-ion battery during charging or discharging the event of overcharge, over discharge or over-current, it will cause damage or reduce the battery life.
Often see this argument, because the number of charging and discharging is limited, so it should be possible to run out of phone battery power recharging. But I found one on lithium-ion battery charge and discharge cycle test table, on the cycle life data is as follows:
Cycle life (10% DOD):> 1000 times
Cycle life (100% DOD):> 200 times
Which DOD is the depth of discharge the initials. Can be seen from the table, number of charge cycles and the depth of discharge, 10% DOD cycle life than when the 100% DOD for much longer. Of course, if the actual charge equivalent to the relative total capacity: 10% * 1000 = 100,100% * 200 = 200, which the full charge and discharge is better than some, but users of that claim to do in front of some of : In normal case, you should have reservation in accordance with the remaining battery charge runs out and the principle of full charge, but if your battery is expected in the first two days you can not adhere to the time of the day, you should start charging a timely manner, of course, if you are willing to back the charger to the office has a different matter.