Re: 17.6 hours
... the T580 that work issued me is dual battery, much to my annoyance when I went to force power-off the damned thing by yanking the battery only to find the damned thing was still chugging along...
The T580 is... decent enough for what I do with it (infrastructure admin, so lots of SSH, web GUI interfacing, and remote desktop), although Visio still causes it to grind to a studdering halt.
Haven't bothered with doing things like games or media, I have other devices for those tasks.