Here's a little app that might help you monitor battery life. Battery Tile.
Battery Tile | Windows Phone Apps+Games Store (United Kingdom)
Free for a limited time. Hope it is still free when I get my 820.
I think you can purchase it now and choose to install later by email, it will be tied into your microsoft account so you can download it again on your phone when you get it.can you download apps onto your computer. then once my L920 arrived install from my computer??