frugal led light

Sort of following on from the post about lights that suck the last juice from cr123 cells, I picked up a couple of those "Police" branded far eastern made led lights - both 6 led and 9 led versions.

Interesting difference. The 9led one has a booster sandwhich nestled in the top of the tube (which pops right out if you push on it from behind) and draws about 300mA on a fresh cell. I think LED Museum reviewed it a while back. The leds are a bit blue, but even colour. Unfortunately not evenly matched, as when the cell is low I can see 3 distinct brightnesses in the leds.

The suprise is the 6led light. Open it up - no booster. Running direct off the 3v cell. Stick on a dmm and I measure 30mA draw, and it's as bright as my minimag + newbeam. The leds are a tinged a cyan-green at the edges. This seems like it'll be one loooong running light! It even lights enough to see around a dark house on an almost dead cr123 - bear in mind there's no boost cct.

I thought white leds needed >3v to operate. I wonder what brand they are...?

A nice touch is you can unscrew a collar inside the head and drop out the led assemblies on both. Very nice shell for modding, given the £7 (inc delivery) price! /ubbthreads/images/graemlins/smile.gif

White leds run fine on 3v, they're just dim at that voltage (5 ma in your case, 30 ma for 6 leds).

L91 AA lithiums are about 1.7 volts each, so two of them will run a white led at about 15 mA, which is reasonably bright. I replaced the incandescent bulb in my 2aa minimag with a 3mm white led from lsdiodes.com, and put in two L91's. The result is a light about halfway between the original CMG Infinity and the later Infinity Ultra in brightness, that should have absolutely stupendous runtime.