Ahh, my apologies, the box does claim 6 hours. (I seemed to recall reading 4 somewhere) That's what I based the "two hour commute" on, two hours there, two hours back. Based on a 6 hour battery life, that'd make it a 3 hour commute. On my example long-distance run of 80km, it'd just make it.

That said, in practise for me, I've turned it on before leaving home, and found it turned off when I arrived at work. That'd be leaving sometime before 4:30AM and arriving at or slightly after 5AM. This does not inspire confidence.

Still, the good news it worked for [MENTION=40124]ItsJustMe[/MENTION], and probably countless others. I suspect I am in the very small minority.