Cannot charge battery via usb cable to pc after upgrade firmware and android version to 4.1.2 (Galaxy S2) I cannot charge battery via USB cable to PC after upgrading firmware and android version to 4.1.2 (Galaxy S2 mobile). Anybody please explain to or advise me, how I can I get my PC charge my mobile's battery via USB cable.
Many USB ports on computers do not have power sufficient to charge a phone battery.  Does the phone charge with the plug-in type supplied with it? Some computers will advertise a charging USB port.  The default current (amps) is 1/2 A or 500mA in a standard USB connector.  It is not uncommon for tablets to require 2 Amps.