First maybe a bit of history.
increasing power to the LED
Through the late '90s the only available LEDs were 5 mm types ~3 lumens each. Then in 2001 Lumileds made the 1 watt LuxI, 30 (later 42) lumens at 350 mA. Nuwai made a torch using a 3V CR123A battery, a LuxI LED and a circuit that feeds 350 mA to the LED called the Quantum (Q1). Then Lumileds came out with the LuxIII 75 lumens at 700 mA. Nuwai replaced the LuxI with the luxIII and called it the QIII. Unfortunately the circuit was still feeding out 350 mA and the QIII is not brighter than the Q1. CPF members discovered with a 3.6V RCR123A they can push 700 mA into the LED and increase brightness to 75 lumens.
Improving the LED
When Cree came up with the XR-E at double the brightness at the same power input many CPF members tried to upgrade their torches. But the Cree does not work with reflectors designed for the Luxeons. OOPS. SSC had been making Luxeon clones under licence for the local market. They put a Cree die inside a Luxeon style case and called it an SSC-P4. Now we can do a direct swap.
Heat management
From the following EDC-P7 review.
http://www.candlepowerforums.com/vb/showthread.php?t=213131
After 10 minutes, the body became uncomfortably hot (keep in mind that I am in foodservice, and have been know to take pans out of the oven onto the stovetop with bare hands). After 20 minutes, the body temp was so high, that I turned it off for a few minutes because I feared for the Li-ion's safety. I let it could cool down, because of the high temps to the batts (sadly, I forget to take home the IR thermometer from work, so not sure of temp). Total run time was 45 minutes when I noticed a significant decrease in brightness, at which time I stopped the test.
Edit: for the above temps, I left it on a table top w/o touching it, to accumulate max heat. I re-did the test, but this time holding it in my hand the whole time. From 5 to 20 minutes, there was so much heat that I had to switch hands, but it never became so hot that I had to give up turn off the torch. Keep in mind, though, that I have asbestos hands. You may have to switch hands more often or turn it off, if the heat gets too high. After 25 minutes, the heat generated was not a problem.
I had to switch flashlights after using my EDC-P7 for 5 minutes. That is why most 1*18650 SSC-P7 runs at 2 amps (they all claim 2.8A so not to lose face).
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Now let us look at design parameters.
Choosing the LED
The LEDs in the link in the OP falls into 3 groups.
Cree XR-E, XP-E, SSC-P4, Luxeon Rebel.
These are small die LEDs and can be focussed very tightly for maximum throw/brightest hotspot. Max current 1-1.4A. Max lumens 250 LED, ~200 OTF.
Cree MC-E, SSC-P7.
4 dies per LED makes a bigger LED area and bigger hotspot. Unfortunately the reflector has to be deliberately defocussed to hide the gaps between the dies making for some floody lights. 700 LED, 500 OTF lumens max.
Cree XP-G, XL-M, Luminius SST-50, SST-90.
The bigger dies make for a bigger hotspot and more light.
XP-G - 350 LED, 275 OTF lumens max
XL-M - 160 LED lumans @350 mA, 750 LED lumens @2A. Production units not yet available.
SST-90 - 2250 LED lumens at 9A.
In General
The 1st group will give you the tightest hotspot, the others give bigger hotspots or are out and out floods.
Cree XR-E, XP-E, SSC-P4, XP-G can be driven comfortably at 1A though have been driven up to 1.4A.
Cree MC-E, SSC-P7 can handle 2.8A.
Luminius SST-50 can handle 5A.
Luminius SST-90 can handle 9A. An electric frypan or kettle or toaster runs at 12A. Look at how thick the wire is. You can go down one wire size but that is still hard to manage.
Choosing the battery type and driver.
LEDs max out at between 3.2V to 4V (Vf).
3*NiMH gives 4.05-3.6V. A single Li-ion gives 4.2-3.6V. So it is possible to direct drive an LED without a driver. Both the EDC-P7 and the P7 Mag mod are DD with no driver. (XR-E, SSC-P4, SSC-P7)
Most of the newer LEDs have lower Vf so it may be wiser to use a dropping resister or driver. (XP-E, XP-G, MC-E, SST-50, SST-90)
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Drivers come in 4 Types - boost, buck, boost-buck and PWM.
Boost drivers take a lower voltage and boost it to a useful voltage for the LED. 1.5V 1AA or 3V 2AA/1 CR123A primary.
Buck drivers take a higher voltage and lower it to that is required by the LED. Multiple lithium batteries. Most buck drivers add an additional volt to the Vf as its input requirements.
Boost-buck or buck-boost can take a wider input voltage range and either boost or buck as required.
PWM (pulse width modulation) does not change the voltage. It controls brightness by doing
_|¯¯¯¯¯¯¯¯|_ or _|¯|_|¯|_|¯|_
It controls brightness by changing the width of the pulse. Often it is used in combination with a dropping resistor, boost or buck driver.
Choosing the Flashlight Body.
Your choice of batteries determines the body type.
Using NiMH DD means 3D Mag or 3C cells in a 2D Mag body. You can do 3C if you can still find a C size heatsink. There have been a few 3AA in a 1D body and 4D with buck driver.
Note the Mag mods so far are designed for the incandescent body. The new Rebel MagLEDs are different inside and mod procedures and parts may not work or have to be changed first.
P60 style lights preferably one that is bored out for 18650. You only have to modify the light engine/drop-in. And if you mess up you can always buy another drop in.
Other 18650 lights. The light engine and head may be glued down. By the time you take it apart you may have damaged some bits you need.
Heat management
The LuxIII is a 3 watt LED. The replacement SSC-P4 is a 3 watt LED. So any flashlight that can handle a LuxIII can also handle an SSC-P4.
The Cree XR-E, XP-E, SSC-P4 is a 3 watt LED. The SSC-P7, Cree MC-E is a 10 watt LED. (The SST-90 is a 35 watt LED) So you need to figure out how to get rid of 3X the heat.
In the 2nd photo of the How To Mod a Maglite P7 - 38 PICS you can see the size of the heatsink for a P7 magmod.
http://www.candlepowerforums.com/vb/showthread.php?t=238641
In the P60 drop-in style bodies CPFers have been stuffing aluminum foil in the gap between the drop-in and body to increase heat flow. Or fill the space with arctic silver. Here is what Bigchelis did to a DeCree-XPG.
http://www.cpfmarketplace.com/mp/showpost.php?p=2453829&postcount=85
I will make comments for the P7 and driver mentioned in post #6 in a separate post.
