Q3J or Q3K for Surefire KL1, whats better?

Im thinking of ordering a couple of Luxeon HD Leds so I can mod my KL1 Head. The head will be used on an E1E with standard 123 Battery and/or an E2E using the Pila 168S Rechargeable Battery. I assume the Batteries dont make much difference as the Voltage will be regutated at the KL1 Head. The Q3J Luxeon is rated between 3.27 - 3.51 Volts and the Q3K is 3.51 - 3.71, am I being too critical or is there a better suited of the two choices? Thanks

From what I understand the lower voltage is better, it makes for a more efficient LED.
RC

My KL1 has an R2H in it. So long as I am using it on a fresh cell, one cell drives it well and it stays nice and white. Once the battery is depleted a little, it starts down the green road. I have been using with 2 cells now and it doesn't seem to get green at all now and the white light produced is a much more pleasing hue than the Q3J in my McLux (although the McLux is brighter due to the converter).

I seem to be getting the jist of all this, It would be better to get a lower forward voltage so I can use the KL1 head on a single cell (in my case the Surefire E1 body). seems like the J is the better option with the lower forward voltage. Has anyone used this LED on a E1 with KL1 head? If so what are your thoughts.

andyz,
A lower forward voltage will mean a slightly longer runtime. I'm thinking 10% at the outside. I have an R2K modded KL1 that I often run on a single cell. It runs fine. Given a choice however, I would go with the lower forward voltage. The Q3J's that have been going around have been nice and cost effective. The light stays nice and white through the life of the batt.

Good to hear Chop, I ordered 4 Q3J's last night. I see what you mean about these forums, It was only a couple of days ago I was saying im not going to mod for a while and here I am without even one of my lights arriving and allready ordering HD's for modding. I read a few posts on replacing the LED's and it looks pretty easy. Ive got all the right gear to do the job so I thought why not, at least if the lights arrive and im not happy with the KL1 performance then I can bring out the hammer and blow torch and crank that baby up /ubbthreads/images/graemlins/grin.gif

andyz,
There are people on this forum that have been around alot longer than I, but I have done more than a few KL1's. If you need any help, don't hesitate. Just PM me.