Method and apparatus for fast battery charging with universal high power input source

In described examples, a connection is detected of a voltage adapter (140) to an electronic device (110) via a USB cable (130). A non-zero predetermined current is selectively sourced or sunk to or from one of a first data signal conductor (DP) and a second data signal conductor (DN) while providing a non-zero voltage to another one of the first and second data signal conductors (DP, DN) to configure the voltage adapter (140) to provide charging power to the electronic device (110) via first and second power conductors (VBUS, GND) at a particular voltage level above a nominal voltage level. The voltage adapter (140) selectively adjusts the charging power to one of a second particular voltage level and a default voltage level. The voltage adapter (140) automatically adjusts the charging power to the default voltage level in response to disconnection of the voltage adapter (140) from the electronic device (110).