Nokia Lumia 900 User Manual page 11

To avoid breaking the USB cable connector, be careful when connecting or
disconnecting the charger cable.
Charge from a computer
You can use USB charging when a wall outlet is not available. Data can be transferred
while charging the device. The efficiency of USB charging power varies significantly,
and it may take a long time for charging to start and the device to start functioning.
1 First connect the USB cable to the computer, then to your phone.
2 When the battery is full, first unplug the USB cable from your phone, then from
the computer.
If the battery is completely discharged, it may take several minutes before the
charging indicator is displayed or before any calls can be made.
If the battery has not been used for a long time, to begin charging, you may need to
connect the charger, then disconnect and reconnect it.
Get started 11