LED flashlights: Lessons learn from an early adopter

I've been buying LED flashlights for a couple of years now. I made a mistake or two along the way and thought you might be able to benefit by my experience.

First: it doesn't make any difference how many lumens you have if you can't afford the batteries to generate them. I bought my lovely wife a Frontgate "500 lumen" model that came with free imprinting of one's name ("Kate!") Maybe it really was putting out 500 lumens (one of our neighbors said that they thought it was a motorcycle coming down the street), but the original 4 CR123A photo lithium lasted probably 10 days or two weeks, used probably 30-40 minutes per day.

The price to replace them: $6.49 each, retail, and it takes 4 to run the thing. You can get them for $1 each or so, online, but, I thought, why not use rechargeable ones?

I tried this, but the only 'RCR123A' batteries I could find are made by Tenergy, and they have some unfortunate characteristics for use in flashlights. They go out without warning. I found this out being 40 minutes away from home on a walk one night, and the flashlight just went dark with 2 seconds warning.

It turns out that 131 lumens is plenty. I ordered a Maglite rated at this that uses 3 D cells and it's fine for our dark nights. The instructions say "don't use rechargeable batteries" and to that I say "bah!"

I tried our eneloops, which are AA batteries that come with a D-sized shell. This didn't work to start with, but I looked at the cap end of the flashlight that connects to the bottom of the battery. It was too wide for the little AA eneloop, so I stuck in a square of aluminum foil and voila! These batteries work fine in this flashlight, and get dim slowly rather than cutting off quickly and leaving you in the dark.