Why won't my android phone charge from my computers USB port? It actually seems to drain the battery Why won't my Android phone charge from my computers USB port and why does it seem it actually drains my battery?
To expand on Matthew's comments, from wikipedia (http://en.wikipedia.org/wiki/USB):


  As with previous USB versions, USB 3.0 ports come in low-power and
  high-power variants, providing 150 mA and 900 mA respectively, while
  simultaneously transmitting data at SuperSpeed rates.[25]
  Additionally, there is a Battery Charging Specification (Version 1.2 –
  December 2010), which increases the power handling capability to 1.5 A
  but does not allow concurrent data transmission.[22] The Battery
  Charging Specification requires that the physical ports themselves be
  capable of handling 5 A of current[citation needed] but limits the
  maximum current drawn to 1.5 A.


In other words, it's worth it to try as many sources as you can find when looking for a good charging port.