Peter Cole wrote:

Something doesn't add up. The spec claims 10 hr run time on full.
Assuming 6 W-hr per C cell, that's 18 W-hr for 3, or 1.8 W for 10 hr. At
360 lm, that's 200 lm/W. Cree's absolute best LED (now only being
sampled) is 132 lm/W.

You're right. A similar flashlight from the same manufacturer that uses
4 C cells is rated at 3 hours full brightness, so two hours would be
more likely. Interesting the wording "fully charged" apparently implying
that they're expecting you to use NiMH batteries.

MAybe it's worth a try since Costco lets you return costco.com stuff to
any store.