Inside the box, the Microsoft Band 2 comes with a USB charging cable. To charge the Microsoft Band 2, plug the USB end of the cable into a powered USB port (USB 2.0 or greater) and connect the magnetic charging connector on the USB charging cable to the charging port on the clasp of your Band. The battery on the Microsoft Band 2 can reach 80 percent after charging for just 20 minutes.
Full story from the WindowsCentral blog...