When it's time to charge Glass, you'll see an empty battery icon with a flashing red bar on the display. Plug the charger into a wall outlet and plug in the micro USB cable included with your Glass to recharge the battery. While charging in an inactive state, an empty battery icon on the display will animate whenever the display is activated.
The Power LED
While Glass is charging, the LED on the curved back of the device, near the power button, will pulsate slowly. It will remain solid when Glass is fully charged.
Checking battery level
To check the battery level while using Glass, swipe back from your timeline until you see the Settings bundle.
Battery Charged indicates that your Glass is fully charged.
The connectors of the cable and charger are two-tone so you always know which way to plug in the USB. On Glass itself, the cable is at a right angle facing backward (the white half of the connector facing out) so that the base of the connector can be used to stabilize Glass on a flat surface while charging.
You can use the included USB cable to charge Glass, but you'll get more power directly from a working wall outlet. Use the included charger to charge Glass fastest.
Extra chargers are available for purchase in the Play store.
Best charging practices
Make Glass inactive when not using it
Putting Glass in an inactive state will lock the touchpad, disable incoming phone calls, and turn off notification chimes. This will save battery while you're not using Glass. Enable On-Head Detection from the Settings bundle to put Glass in an inactive state automatically whenever you take Glass off.
Hard power down
While Glass is plugged in, pressing and holding the power button for 15 seconds triggers a hard power down. The LED light turns off and Glass will not charge when hard powered down.
Turn off Glass while it's charging
Charging Glass automatically turns on the device, even if it was powered off before plugging in. To power down while charging, press the power button for 3 seconds. You'll know it's still charging if the LED light pulsates.
If the LED light turns off, you’ve held down the power button too long. Start up Glass again, and try pressing the power button again for only 3 seconds.
Powering Glass after a long period of disuse
If you haven't charged Glass for a couple of days/weeks, it may take longer to charge Glass. In this state, it's normal to not see the empty battery icon on the display. It's also normal that Glass won't turn on when you press the power button. But don't worry. Grab a cup of coffee and return in a bit, and Glass should turn on normally.