I will run it off 3 AA batteries, NiMH or Lithium primaries like Energizer Ultimate (I hope they sag fast enough or I'll have to get a driver capable of handling more than the standard 4.2v, maybe even more than 4.5v just to be on the safe side).
I think the price difference between XM-L and XP-G is not that great, and I like the thermal efficiency of the XM-L and its being more floody.
I really don't like those million modes drivers with groups that change on low mode... I think they are obnoxious. I much rather have a permanent mode group, or some other way of changing groups (e.g. cycling through all the modes twice).
I have ordered some 1.4-1.5A Amp drivers , and plan on building a lower output XM-L P60 pill just to see how it fares ..
I expect output to be around 400 to 500Lumen , and thats good output for 1.4 to 1.5 Amp , and since the emitter is under driven , no heat related sag or other issues + lots more run time .. [ No fear of running high for extended periods ]
Yes a XP-G R5 [ recent ones ] can do 400+ , but they also seem to sag a fair bit as the light warms up ... The XM-L will have an advantage here and hold output .
I don't think this is about the emitter ..i believe we're talking about the driver here .. but don't listen to me ..I'm only smart enough electronically to burn down half the house ..I assume there are others out here much more qualified to help you burn the entire house down :P
Here's a little advice on converting the C88 to XML since I did mine today. It does take a 14mm PCB and a 17mm driver as stated before. I had a helluva time getting the emitter loose until I took a little butane torch (my cigar lighter) and heated up the inside of the pill (take the driver out first!) then it just took a good twist with a pair of needle nose pliers and it broke loose. Then there's cleaning out the old adhesive... that's never fun.
The PCB of the Q5 is thinner than the XM-L one I have to replace, so it added a < 1mm gap between the head and the body. If one were so inclined, they could sand it down to the same thickness as the original. I was lazy this time so I didn't. The bottom of the reflector is completely flat, so try to keep the wires and solder as low as possible. You may need to replace the original isolation disk, but regardless I recommend sticking it to the reflector, not the emitter (much more effective and makes more sense).
I used a NANJG 105c driver and I couldn't quite get it to sit right, but a little filing fixes that. I also put an isolation disk on the driver (especially these with chips on the bottom side) just to be safe. With the spring on the driver the battery carrier still fits nicely and there were no contact issues.
I am getting 2.7 Amps on fully charged Duraloops (which probably sags quickly) and I ran it on high until the low voltage warning kicked it 50 minutes later. The light was hot, but manageable. The pill is massive and does a nice job with the heat. I looks like it averaged 2.1 - 2.2A during the run on high. Oh... and it out throws my only other light with a reflector about this size: the 980L. :)