During the Intel Developer Forum Spring 2007, the USB Implementers Forum (USB-IF)
announced the availability of the Battery Charging Revision 1.0 specification.
Consumers like Windows Mobile users currently use USB to charge batteries on
their peripheral devices. With the announcement of the new Battery Charging
specification, the USB-IF Battery Charging Workgroup has defined a standard way
for portable devices to draw current from wall chargers or PCs. In addition, the
Battery Charging specification allows PCs and hubs to provide increased levels
of current, in order to shorten the charging time of connected portable devices.
"The USB-IF has responded to the growing trend among mobile devices to
utilize USB for charging capabilities," said Jeff Ravencraft, USB-IF
president. "The Battery Charging specification allows multiple types of
portable devices to charge from USB ports or from a standards charger, thus
eliminating the need to carry multiple chargers for different kinds of
One of the issues addressed with the Battery Charging specification is
defining a mechanism for portable devices to detect whether they are attached to
a wall charger, high current host or hub, or to a regular host or hub. When
connected to a wall charger or high current host or hub, portable devices are
allowed to immediately draw currents in excess of 500mA. When connected to a PC
or hub, portable devices are required to limit their current to 2.5mA, 100mA or
500mA, as required by the USB 2.0 specification.
The Battery Charging Workgroup has also defined a Dead Battery Provision in
the new specification, which allows portable devices with dead batteries to draw
100 milliamp (mA) minutes or hours before connecting. This permits portable
devices with dead batteries to be able to charge from a host, even if they are
not able to power up.
Cheers ~ Arne