I recently bought a Solarforce L2m flashlight host (head assembly, battery tube and tail switch assembly). The L2m is only 4.5″ long (~115 mm).
The head assembly is designed for a Surefire P60-sized drop-in. Fizz753 over at Candlepowerforums.com has compiled a very complete and up-to-date list of LED drop-ins.
I used one of my modded Cree XR-E (Q5 bin) LED drop-ins with a DealExtreme 16-Mode 3W 3.7V 7135 Circuit Board (SKU 7612) stuck in it.
Power is provided by a single protected Li-Ion RCR123A 3.7V battery. This 16340 size battery gives about 30 minutes on full with the 7612 board. I haven’t measured the current out of the board, but the specs say 1000 ma, so the output, according to Cree (Cree® XLamp® XR-E LED Data Sheet – PDF), is probably about 180-200 lm.
The next mod I made was replacing the reverse clicky switch with a McClicky switch. The last thing I’ll probably do is replace the crenelated ring on the head with a plain one.
Over at the CandlePower Forums mod discussions, the Seoul Semiconductors Z-Power LED P7 has been one of the most popular LEDs. The reason is simple: it puts out 700-900 lumens at 2800 ma. That’s very bright.
In the Home Made and Modified Lights section, jirik_cz modded his Ultrafire C2 flashlight with a SSC P7. For power, he used a Li-Ion 18650 3.7V battery directly driving the LED. It is a simple and elegant mod.
I happened to have a spare Ultrafire C2 flashlight waiting for a great idea like jirik_cz’s mod. I already had the P7 emitter (C bin) mounted on a heat sink base. An advantage of having the P7 emitter on a heat sink base is that the positive base of the bare emitter is isolated from ground.
I used a Dremel to enlarge the Ultrafire pill so the P7, on some heat sink compound, fit perfectly.
For the positive battery contact side of the pill, I stripped a 17mm diameter circuit board and soldered the LED leads to it. To accommodate the larger diameter LED, (the Ultrafire C2 uses a Cree XLamp® XR-E LED), I enlarged the hole in the reflector with a reamer.
Thanks to jirik_cz, now I have a 5″ (130mm) long flashlight that is a bright as my Roar of the Penguin.