Consumer Report Tells You: What you need to know about Google Glass: They got 3 Hours out of it

Battery life

Google claims one day of battery life for “typical” use. We noted about 3 hours of battery life under what we considered continual “moderate” and “heavy” use. The protocols included tasks such as following turn-by-turn directions, recording video, and listening to music.

http://www.consumerreports.org/cro/magazine/2014/10/what-you-need-to-know-about-google-glass/index.htm