KL4 & L2 Upgrades

Having just upgraded my Gladius to a XP-G R5 I now want to upgrade some of my older lights to some newer emitters. I have a early 4 flats L2 and a Blk Kl4 with the E2d bezel swapped onto it that both could use some work, now I'm not up on the newest & greatest so is a P7 in the KL4 and a 2S2P MC-E in the L2 still the way to go ? Will keep the stock drivers and all lights are fed AW cells.

The latest and greatest us the Cree XML. It's more efficient and it's a single die instead of quad dies. This makes for a more artifact free beam.

Ok so XML's to replace my Luxons the KL4's seam to have been heavily documented before in various Mods the L2 should be similar inside, just need to work on any shimming of the emitter as needed. Anyone else have any tips/ideas I have only swapped the Lux 3 in my Gladius for a P4 and now a XP-G so far.

I'm not that familiar with the KL4's, but since you mention that you'd like to retain the stock drivers, you might find my L2 thread interesting. In my first post I included a few links to some exceedingly good threads, both on the L2 and the KL4.

(Although that modest project of mine is still on hold, it looks like a 2s2P MC-E is still the way to go regarding the original ~6.5 volt LuxV drivers.)

Thanks Kestrel I have done a few searches and seen a few of those threads but there all worth reading, I picked up a spare KL4 & E2DL heads on the MP to mod the KL4 (it belongs to a buddy) and swap out then do the original so he does not have any down time (Only light light he owns) I still am on the look out for a stock L2 head to mod so I can keep mine stock.

Ok where are you guys getting emmiters ? My last few came from DX or the Bay it looks like I'm gonna do the following.

My L2 - MC-E
My KL4 - XM-L
My Buddies KL4 - thinking P7 (will see how mine goes)
My E2DL - ?

If the KL4 head is the old version that uses a Luxeon V LED, then the driver is a boost driver that was designed to boost 2x123A (at roughly 5V) to power a ~6.5V LED. If you use a Seoul P7 with Vf of around 3.0V at the boost driver's drive current of around 650mA, your Vbatt > Vload and you'll be in direct drive. Whether or not the boost driver will like this depends on how hard you run the LED in direct drive and how robust the driver is. For 1xLi-ion at a nominal voltage of 3.7V, a P7 could draw over 2A drive current. I know that folks on CPF have done this mod and have claimed that it works, but my opinion is that it is unwise and the numbers don't bode well for product reliability/longevity.

You will face the same issue with an XM-L swap in an old version KL4. In fact, it'll most likely be worse than for a P7. At 3.7V Vf, an XM-L will draw well over 3A. You risk cooking the LED and the boost driver.

For the old version KL4 that uses a Lux V, the standard LED swap is with a Cree MC-E wired in 2S2P. That is electrically compatible with the stock SureFire boost driver.

Now if your KL4 is the new version that uses a Seoul P4, then a direct swap to a P7 or XM-L should work fine, at least in terms of driver compatibility. You'll probably have to drill out the reflector opening to fit the larger diameter P7. You may also have to change how you solder the P7's leads to the KL4 since the P7 is much larger in diameter than a P4. For the XM-L, you may have to shim it to the proper focus height, depending on what MCPCB the XM-L is on.