Soldering looks good and thick but yet you never know... maybe you overheated something? Person need to be expert for drivers to reveal truth.
If I don't have good results I just toss driver in a trash(plenty of guys there :) ) and get another one. Why bother for few$?
But however I would change main spring with carobronze one.
Before you give up on that possible damaged XP-L, test direct driving it with an omten switch & 18awg wires. If you don’t get a much higher Amp then you know it is a bad one.
You say scrape the wire, if you are talking about the delicate bond wires, then yes if you have disturbed them in any way you have most likely damaged the emitter 
I don’t think my XP-L was damaged. I think you may have missed the part where my tail reading was the same before and after the dedome. I didn’t make it the clearest as it was across 2 posts.
Hehe, yes when i read them again i got that now.
I would still test a DD set up before you give up on it though.
4.5A is just so low for an XP-L on a FET or DD i think it is about the lowest i have read about here & because this is the BLF i don’t think many of us ever cherry pick the emitter.
I remember djozz did when he bought cheap XP-E2’s from Mitko to do a write up & test on it but right now thats the only instance i can remember.
Well, i usualy get 4.5-5.1amps from either U2-u3 or V6 bins with a BLF17DD driver so your result is quite okay: consider that the battery will drop very quickly from 4.2v, no there is no point the chase more - with a 4.25v battery youll prolly get above 6 amps at startup but yet, it would drop even faster
I wonder how purple 4200 will perform vs green 4200, cant wait 
I ordered it some time ago, its 100% as V5 1A that Simon from Convoy offers for 3$ or something- absolutely the same emitter- 300 or so lumens at 700ma
Yes. It is nice to experiment and stacking chips but we need to think about runtime. Single cell light should not go over 3,5a(15 or less minutes of full power). I am afraid what would be runtime with 12-15 chips 
Edit:
Any chance they will be offering smaller single cell brothers? I think that would be a lot interest for them also.
It seems the UF1405 coupon has expired :( Any chance of extending it?
Hi Lothar, UF-1405 $25.99 Code: UF-1405, thanks for your liking this deal from GearBest.
You also can see more deal in OP OFFICIAL Group Buy UF-1504, UF-1504 host, UF-1405, tail switch, 26650 batteries DISCOUNT CODES EXPIRED!!!!!!!!
Thank you :) I could not resist pulling the trigger on the UF-1405
I can lay to rest the theory that I have stacking problems. I just checked with my new power supply and at 4.2 volts the most the driver will pull is 3.5 amps. when I raise the voltage to 4.6 volts it has no problem getting 5.2 amps.
Thanks for testing & confirming that Mitko :), i have been wondering about those for a while now.
I don’t know if i should ask this, but will using xpe2
Make it throw better?
At 1-2A possibly, but over that the XP-G2 wins. The XP-E2 just does not handle high currents. The XP-G2 can be pushed much harder with much more output.
But would i get more forward lumens due to larger lens? Lets say
Compared to an sk68 lens?
Yes but that goes for any LED in the 1504 vs sk68
Actually I think you’re talking about candela, lumens has little to do with the lens other than its transmittance and closeness to the LED.
But n10sivern’s point is that the properties of the LED don’t change just because it’s behind a different lens. At even the modest 3.3A I was able to get into the XP-G2 in this light, it’ll still out throw an XP-E2.
Oh, and first lighted tailcap 1504.
i was actually thinking that xpe2 has a narrower beam
Angle compared to xpg2. If they have the same angle,
I guess they would have same effect with larger lens?
Regarding cd and lumens, i was actually referring
To the light when zoomed out. Aspheric lights
Will always lose lumens when zoomed in coz some of it will hit
The wall of the light right?
True, but head to head the XP-G2 will overcome emitter size and beam angle at higher amps. The XP-E2 will only win that battle at low amps.
Yes,
Driven at 2,8A XP-E2(dedomed) should throw around 380KCD. Beam distance starts to be useful somewhere at 200 - 400m :)