If a man were to want to construct an LED light from available parts (i.e. drop in LED units, bodies, batteries), but was highly intimidated by the choices available and the technical language, what would he do?

Ideally, said LED light should be cheap(ish), bright(ish), and use rechargeable batteries. Or would he be better off purchasing a light from a fine company such as SureFire, JetBeam, or Fenix?

Yeah, I'd just buy a light that's ready to go. I think putting the bits together yourself is more useful if you have particular needs, or want to dive into the intimidating technical stuff, and isn't all that practical for someone who just wants to see in the dark.

The first decision I'd make would be which batteries you want to use. I originally went with CR123A-based lights, not realising there were other choices with better runtime. If I'd known about 18650 batteries from the start, I wouldn't have spent so much money on batteries and lights I no longer use

If I was starting from scratch now, I'd go with 18650 rechargeables, or maybe even AA rechargeables.

I think we've reached a pint where off-the-shelf LED lights (even the cheap ones) are generally good enough that there's no point in rolling your own. You'd probably be better off just buying one that'll take rechargeable AA, 18650, or 17670 batteries.

17670, you say? I've seen them mentioned, but didn't know anyone had any special fondness for them - what's the story?

17670 is basically just a narrower 18650. Same voltage, but lower capacity.

Many LED lights that take 2 x CR123 lithium batteries will also run off of an 18650 or 17670. Often times, the 18650 is too fat to fit in the battery tube, but a 17670 will fit just fine. I have an older Surefire L4 that I run off of 17670's, because that's the biggest I can fit in the battery tube (and current L4's have even narrower battery tubes, so not even the 17670 will fit).

If I was to construct an LED light for myself, I'd have either 1 mode, or Low/Turbo. I am personally miffed at the trend in clicking 4 or more times on a tail-cap just to select the mode you want. Let the tail-cap turn the light on, and a simple twist of the bezel determine mode.

Low somewhere between 10 and 30 lumens, Turbo somewhere over 120 lumens, depending on your preferences for runtime/brightness plus consistent regulation. The light should remain bright and consistent through the majority of battery life. To give you an example of how a light should not be...Surefire's incandescent lights are a wonderfully bad example. Only maintains max brightness for all of 5-10 minutes, and then it's a steep downhill plunge to 50%. All of my present LED lights have proper and consistent regulation. Now, one thing I would like, when a light drops out of regulation as the battery staggers on it's last legs, is if it slowly reduced output over the next few minutes. Strobing is nice and 'deliberate', but I'd rather have the light trail off, so I can still see what I'm doing while I find a spare battery.

Next, body. I like a thick, solid, rugged tube. It should be able to punch into something without denting in on itself. Hard HA-III anodized. Double O-Rings. It should be able to be submersed in water at least a couple of feet without cutting out. A glow-in-the-dark tailcap might be nice. Those tactical grip-rings are also nice. I'd have the tube come apart toward the rear and have a grip-ring attach there, with a knurled cover for the grip-ring's threads when it wasn't around. I'd also do the same up front, having the possibility of a strike bezel (a ring with steel machined 'teeth' for self-defense), and a standard threaded bezel interchangeable. I absolutely insist on a tactical-style tail-cap if I were designing the light myself, with a momentary-on setting, as well as a lockout feature to prevent accidentally turning on.

Batteries, I'd probably have it accept CR-124A, as well as rechargeables. An interesting idea, might be to power it with a couple of '23A' batteries. These things put out 12 volts each, and are used to power the 'Glo-Toob' device. A bit uncommon as far as batteries go, but I bet they'd make a pretty powerful flashlight. I'd also like to have a battery tray set up so I could pop in batteries that didn't otherwise fit in the tube.

I'd almost forgotten about regulation! I always use rechargeable, protected LiIon batteries, which are pretty consistent in their output until they suddenly die. So, regulation tends to be much less of an issue with batteries like that than it is with gradually-declining primary cells.

The downside, though, is that you really have no idea how much power is left, until everything suddenly goes black.

I always like to have a keychain led around my neck or on my jacket for when the lights suddenly go out. Also good for messing about with your camera without totally destroying your vision.

Don't make me make this the next chat topic:

C30 sez: I like a thick, solid, rugged tube.

(I could also add "steak" to the end of that statement and none would be the wiser! Well.. except us here..

=P

Sorry to hijack, continue on my nyctophobic friends!

*gives adam a wedgie* >.>

I'm with AS on this... I had to try REALLY REALLY hard not to say the same thing.