Why does charging leads to battery losing charge at times
Now your typical wall charger on a smart phone provides 1A of charging current. The USB 2.0 on a computer will only supply a max of 500mA, that is half as much. So if your screen is on and you are using the phone then it is drawing more power than it is taking in since the screen is the largest drain on the battery, therefore the battery will drain while charging on a USB connected to the computer.