I should also pass along what I heard from
daredevil in another thread: that model of light turns off abruptly when the battery voltage gets too low. So if your rides would routinely be approaching the 2-hour mark, that's a possible issue. If you'd only go that long once in a while, then I guess a guy could simply carry some extra AAs along, and reload batteries.
You can cop a charger pretty cheap here. Comes with 4 AA's.
I got one of those, it's sweet
It keeps the batteries topped off with a trickle charge, too. However, I'm transitioning to 18650-based lithium-ion lights from here on... more capacity, faster charging. I'm waiting for my
LumaPower MRV SK to arrive, and
that should address my current setup's lack of long-distance reach. "Only" 280 lumens, but they're almost all focused into one very potent hotspot