The LED indicator will start blinking RED when the battery level is low. To charge the headphones, plug the included USB cable in to the Micro USB socket on the headphone. Plug the other end of the cable into a USB power source. The Red LED indicator stays lit when charging. When the battery is fully charged, the LED indicator turns white. Customers should note to charge the battery before using the headphone for the first time. 3 (Three) hours charge gives approximately 30 (Thirty) hours of playback at medium volume.