According to footage obtained from a Hololens event in Tel Aviv by wearable technology professional Niv Calderon, Microsoft's augmented reality headset will last anywhere from 2.5 to 5.5 hours when all is said and done. This information was given by Microsoft's Bruce Harris, who can be seen in the video below describing a few details of what we can expect whenever the Hololens hits the market.

https://www.anrdoezrs.net/links/3607085/type/dlg/sid/UUhgUeUpU40077/https://www.youtube.com/watch?v=vXu5toPPqVE

The low end of the spectrum is going to be reserved for heavy usage with the most demanding software experiences available, whereas the upper end seems to suggest that more passive use will be possible. It's anyone's guess at this point when, or if, consumers will be able to purchase the Hololens anytime soon, but this recent development provides more credence to the idea that this will be a product in the near future.