I just did a standby current measure, which is a bit tricky given the tailcap design. The most stable reading I obtained was ~1.4 uA on a fully charged 18650. Seeing as how that translates into a couple of centuries for most 18650 cells, I don't think we need to worry, lol.I worry a teeny bit about the standby current for the Strobe switch, but mmmeh. I'm sure the draw is miniscule and hey - future batteries are his problem, I'm just supplying the gift and 2x123's to start! ha.
I didn't test other battery types, but I don't imagine it is very different. End result, your cells will be dead from old age long before the negligible standy current could drain them. :thumbsup: