Headlamps are really the best form of flashlight. If you don't own one I recommend you get one because they put light right where you're looking (like in someone else's face:-) and they leave your hands free. I've got a couple that I bought for camping and hiking and such, but find myself using them all the time when working around the house, doing close work on my electronics bench, etc. The first one I bought was a Petzl Tikka XP and it's been a workhorse for many years now. I also bought a Black Diamond around the same time, but it's not nearly as nice (not waterproof, a single button to cycle through too many options, discrete LEDs for low light mode draw more current than the main LED) but I do use it now and then for things like house painting and working on the car, where I don't want my XP to get spattered or greasy. I know LED technology has advanced quite a bit since I bought them, brightness and efficiency have increased a lot, so I'm often looking at the latest models to see what might end up replacing the XP.
I like the XP a lot, but the spot is rather narrow for hiking. In flood mode, with the plastic diffuser slid in front of the LED, the brightness isn't really sufficient for hiking.
A few weeks ago I ran across an article at the www.light-test.info webside titled "Tikka XP - still dangerous (cree xp-g mod)" located here (the web site is throwing a DNS error for me at the moment). Anyway, great article about rebulbing the XP. The stock XP light is rather cold blue, and I decided that I wanted more of a warm white, kinda like an incandescent bulb color temperature. So I got on eBay and ordered a "CREE XM-L2 XML2 10W LED Neutral White U2-5A3 4000K-4250K on Alu. 20mm Star Base" from seller "led-dna" who is based in Hong Kong. I ordered it December 21 and it arrived just a couple of weeks later. (The package had postage a bunch of $2 stamps all over it, but the exchange rate is so huge that it works out to something like 81 cents USD!). This is what was in the anti-static bag:
The ad says 4000K-4250K "neutral white" color temp, but the insert in the package says 6500K-7000K "cool white" - who to believe? I think it's probably the former because it's has a pretty yellowish cast, very much like an incandescent. So much for the insert.
The replacement process is pretty straightforward, just take the battery compartment back off and remove the three star screws:
The module then pops out:
The Fresnel lens is loosely held by the black plastic holder, which in turn is held in place by the gray molded plastic clips at the top and bottom. Removing both exposes the LED mounted on a standard round star aluminum heat sink:
The stock LED at this point is just sitting there with no other physical securing going on. So you simply unsolder the wires at the star, remove the stock LED, position the replacement LED, and resolder the wires to it. There is some heat sink grease on the back of the star, which makes thermal conduction with a wire bale going back to the circuit board. Presumably to sense overheating, because there is a momentary "blast" button on the top of the XP that gives you really high output for a short period of time before turning itself off if you hold it too long.
You want to pre-tin the solder pads on the new LED before soldering the wires to them. Below you can see the thermal grease on the back of the stock LED (a LUMILEDS with the following on the back: RX0H 8002392 4107LXHLMW1D LUXEON):
I transferred as much of the grease from the back of the stock LED to the back of the new LED. Another thing you won't see in my pix here is I took a small piece of aluminum tape and made the black plastic holder more of a reflector. This really increases the light output of the new LED because it is more wide angle.
Here is a before and after with the XP aimed at my bathroom wall at night. This photo is very underexposed and doesn't really show you the quality of the light outside the central spot, and the semi-gloss paint on the wall is making a strange reflective sheen:
There is a blue area in the center of the Cree beam, which isn't quite as noticable in "blast" mode, and is gone completely when the plastic diffuser is over the LED. The new beam is much wider, and I prefer this to the stock narrow beam.
The whole surgery took maybe half an hour, most of this was spent putting the aluminum tape on the black plastic "reflector" and trimming it so it wouldn't short out any of the circuitry inside. I'm happy with the result, and not to knock the seller, but I wonder if I got the real thing (a high brightness binned Cree). The super low price, the wrong color temp on the label, the bluish blob in the center, and no part number printing anywhere on the Cree make me somewhat suspicious.