There is one thing I forgot to ask, are your DMM probes thick enough to measure high current? I realize that most of the original probes that come with the DMM are not good and we usually make our own one by using 22awg or thicker wires.
To answer your questions above:
Yes the Qlite is a good one and it is actually a variation of these Nanjg-105C. If you want to bump up the current you can do it by adding extra 7135 chips , or you can ask Richard (from mtnelectronics) to help you to do so when you order from him. I modded a JAX Z1 for a friend before and I used this Qlite driver too, it works like a charm.
2. Yes, you need 22awg or thicker. But bear in mind that going too thick may cause some problems to the assembly later.
3. Spring mod is necessary to reduce the resistance in all the springs.
I think that’s about it and waiting to see your results later.
Everything bibihang has said so far is pretty spot on, however I would predict the Vf to be closer to 4v in his theoretical calculation. No biggie.
Your 2.2A with the dedomed XP-G2 is only slightly lower than I had with the stock driver with jumper wires on the springs. If memory serves me correctly I was getting 2.3-2.4A. Modding the springs may be all you need to do to make up the difference in the tail cap readings.
You’re going to spend a lot of money on a new driver (or spend a fair bit of time making the 17mm driver you have fit) compared to adding 2 R330 resistors on the sense resistor. Start with one and take a reading, if you’re not satisfied that it’s bright enough, add the second. I’m getting around 4.6A at the tail with 2 and it makes 204,445 candela. As a side benefit you don’t lose the ability to run with the second battery when you need more runtime. Personally I’d rather carry my extra lithium-ion bomb in my light, where it’s less likely to be damaged when I need more runtime.
That said, bibihang is right that you’re still not using the most efficient driver in the world since it’s a buck driver.
Oh, and your batteries make a huge difference in measured output. Try it with 2 good batteries or 1 great one (like an Efest purple) and I’d be amazed if your reading didn’t increase. The 5200mah battery you have most likely is limiting your current due to voltage sag. I got a measurable difference going from 4000mah king Kong batteries to the Efest batteries, and yours is even more susceptible to voltage sag than the KK’s.
Also do your best to take your reading at 30 seconds. Set everything up with a cheap battery so that all you have to do is put in the good one (fully charged) and start a stopwatch when you turn it on.
I’m beginning to think this is mostly a spring and battery issue.
