I recently bought one of the fake Solarforce L2m’s with the xm-l u2 emitter. This is a very bright little light on aw 16340 imr’s. It will not run on cr123 primary’s , nor will it run on cheap ultrafire 16340’s. All it does on either of these cells is come on a very low, almost moonlight mode, and nothing else. When you try to change modes it kind of flickers and stays at the ultra low mode. On the imr’s it changes through the modes with no problem at all. I like this little light a lot but am just curious if this is a defect in my driver or does the light just require that kind of current. What do You guys think? Am I headed for a problem that will kill my little light or should I just keep playing on imr’s and not worry about it? We tested it at 561 lumens in our light box after 30 seconds and 8800 lux at 1 meter on imr cells so it has very impressive performance for a 4” $15 light imo.
My guess is that the voltage of the primary is to low to run at full power and the ultrafire 16340s are just crap.
Are the aw 16340 longer in size than the ultrafires? Could be a tailcap/connection issue
Good point. Have you tried the paperclip trick?
As Scaru said above, I can almost guarantee the problem is with the batteries - and the drop in, maybe sort of.
I have a few of the red UltraFire batteries, and not only do all of them under-perform, but two of them trip and cut out at any decent enough draw to run any decent to good drop-ins or lights that I have.
For $15 I got an UltraFire wf-502b as my first P60 light with an XM-L drop in included and it runs fine on any of the UltraFire crap batteries, and until I bought a couple Solarforce L2s and Manafont UF 3-mode XM-L drop-ins and some better batteries, that 502b appeared to be insanely bright to me. Now, it is obviously inferior. But it all makes sense. If I can get a 502b body alone for $6 or so shipped - then obviously for a total of $15 that drop-in that it came with is a cheap cheap generic, and doesn’t meet the standards of the drop-ins MF sells separately. In other words, whatever the driver is in that generic cheap drop-in, it’s not trying to pull much juice if those sad batteries can run it. It won’t even try to pull more from the newer, better batteries. Same results.
In addition, I suspect that drop-in runs a very narrow voltage range, because when I put that drop-in in my 501a, and try to run it with a single cr123a (3v) it lets me run through the modes, but is very dim. In your case, your drop-in wants more than 3v minimum. I have some 16340s on the way, and an L2m battery tube, so I’m pretty excited to put it all together. And I would suggest investing another $15.98 in one of those MF UF 3-mode XM-Ls. Your sweet little pocket rocket will impress you even more, especially if you stick with better-quality 16340s.
I just measured both cells. The ultrafires measure 32.70 and the aw’s measure 33.25. I dont know if that is a significant difference or not. Excuse my ( newness ) but I don’t know what you mean by the paper clip test.
32.70? Do you mean 3.27? The "paperclip" test is when you remove the tailcap and use a piece of metal to replace the tailcap. (back of the battery to the battery tube)
Another newbie question. Does the above mentioned drop-in require soldering or does it screw or press as one unit into the head of the flashlight? Would the drop ins that E1320 sells fit in this light? Possibly the 5 mode with no blinky modes?
E1320's drop in will fit as will the manafont drop-in. No assembly required.
Sorry. Yes I meant 32.70mm which is 3.27cm. I will try the clip test thanks.
Oh, length. I thought you were measuring voltage.
Ok, now this is weird. I just tried all three cells again and all three worked perfectly. I have repeatedly tried all the different cells with the same results, with only the imr working. Now they are all working even the primary. Idk?
The reflector screws on to the brass pill. Is that a normal setup? Are the drop ins from Manafont and E1320 the same way? I don’t mean to sound redundant but I really do want to learn about this,
In general, yes, they are assembled the same way. I suspect the issues you are having are still from inconsistent, poor quality cell function. When we refer to “drop-ins” we are referring to the entire module that fits in the head of the light host. Some have better drivers or programming than others and some have better components than others - meaning when we pay so little for just high-output electronics, it’s likely we’ll get a dud here and there. Sounds like you got an OK deal with the fake SolarForce and whatever drop-in that came with it, but I’d definitely at LEAST get a better reviewed set of batteries. And you’d really appreciate a better drop-in as well, I’d guess. AND…when you get around to it, order a REAL SolarForce host and just take a look at the differences. 
I would like to try the drop in scene. I might see if I can buy a better quality drop in and definitely will buy some better cells. My brother has some Eagletac 2500’s that seem to do really well.
It could just be a connection problem with the tailcap. Problems like that will be inconsistent. As the AW was slightly longer it’s going to be pressed slightly harder against the tailcap making a slightly better connection, which may explain why the UF’s weren’t working before. If you unscrew the inside of the tailcap a little you’ll get a better connection, you might need to place a washer underneath.
Thanks I will try this.
You should measure the potential difference between the battery cells. The lithium-ion 16340 cells are rated at 3.6V whereas if your using CR123A (lithium), it is only rated at 3V. A 0.6V difference can make a huge difference in terms of light output with the Cree XML emitters because from the 3V, the emitter will dim alot, and using the lithium ion 16340 (3.6V), it will put out a bit more light.
So if your running 3V Primary Lithium cr123a batteries, you are lacking the extra voltage needed. However, if your using 3.6V Lithium-Ion CR123A, they should work like the 16340 (which is a replacement for the cr123a).
Correct me if I’m wrong here.
It's great to have you here, diyau!
I actually have some of each. I originally bought the rcr’s because I had purchased a 4 cell xenon ultrafire flashlight on ebay. This was the light that started the madness for me and my brother (rdrfronty). It was the brightest flashlight that we had ever seen but was extremely inefficient and went through 4 cr123 batteries in very short time so I went to the rcr route. Fortunately my brother started researching led’s and we discovered a whole new world of bright efficient lights. Now I know after reading on this forum and doing a lot of playing around on our own that good quality cells make a light! I wont throw my cheapies away but will put them in a drawer for emergencies only.