I do not see the urge for this copper disc replacing the tail-PCB, it costs time and money, as measured it does not improve the current/output (not surprising with the PCB having massive tracing on both sides), and you do remove the last fusable bit (apart from the internal battery fuse) in the circuitry in case of a direct battery short.
Anything will break over time, use,even wire, especially IF you keep bottoming out the springs….I use both wire and braid depends on the application. Usually use braid on big springs, depending on the application, sometimes I solder bypass to the outside, sometimes down the middle?
As far as the copper plate used for a PCB, you’ll never worry about PCB traces in any light at any amp, and it’s something to do, looks cool, will never burn out, it’s matter of pride, a beautiful functional job well done, regardless what anybody else thinks, and I know its mine and something I’ll keep. 
:+1:
Just like polishing the machine marks, ridges, off the emitter board shelf, and removing the ano from the body for the driver ground ring, chamfering thru holes, all holes, tapping out mounting holes, clean fresh threads, can it be seen, does it show measure??
It might not matter to the BIG scheme of things, but then again, I never cared what other people thought, any way. 
:+1:
W2’s re-flowed, swapped out the FET to a 404DP, Tested on the rock, it’s going to be a bright one!
Yeah well, has this been tested? Will the traces act like a fuse?
It’s really no different than bypassing directly to the mounting screws, just prettier!
For the record:
After I shortened the LED wires in my two 1st batch lights by about 1 cm I measured a current increase of at least 0.5 A.
Could even cut more (LED wires a pretty long in 1st batch lights) but need some buffer since I flash the mcu frequently for firmware tests.
@KawiBoy:
Of couse my remark was meant in a functional way, I would never want to prevent people making their flashlights prettier 
I don’t know how mine was made but it does widen if I push it from the ends. And the length won’t change much, if at all, the way I’ve installed it. Pretty sure it will be fine then.
What you do, Kawi, is the flashlight equivalent of neon lights under a car. Chromed valve covers, chrome alternator, chrome water pump, mirror on the inside of the hood. Flashlight Art. And like you say, you then have a personal investment in it that makes it special to you. And it kicks booty as well!
Earthing “straps” are made from flat flexible braid. Correctly routed it doesn’t “bend round corners”, it should flex in a radiused bend. Earthing “bonds” are made from tubular flexible braid. Both are flexible. Both have their applications. I personally prefer flat “strap” braid for this application, and as previously discussed have had good results using the particular roll of desolder braid which I have to hand. I find it convenient and workable.
Others have different experiences, or different opinions.
If you don’t like the flux on desolder braid, you can always wash it off with e.g. IPA or acetone. Or use the technique posted previously, of using flat nose pliers as a heat sink to prevent solder creeping down it where it isn’t wanted.
I suggest trying whichever type you think best, and see how you get on. Easy enough to change later if dissatisfied.
See e.g. Earthing Straps – Copper Braid Products and Earthing Bonds – Copper Braid Products for some technical information.
That's crazy! If I follow correctly, the FET you swapped in was the A20DP?
Correct
I wish somebody (RMM?) had bought a hundred of these to hot-rod and resell at a premium price, to show the world what can really be accomplished.
I don’t look forward to the eventual cheapening of the retail lights over the next year or two as the beancounters intervene. How long til they bottom out like the earlier soda-can lights did?
There must be a half-life on good design and implementation that could be charted. The curve would be inverse to the profitability, I suppose.
They already cost more than $100 at ali (and more than 100pcs are sold).
Thank you. Ordered me some.
I use the Bopper: https://www.etsy.com/transaction/1257576221 for my copper rounds. She is also here:
https://boppermetalsupply.com/
Might be cheaper on her own website, dunno.
Beverly - great support, reasonable prices. Recommended by O-L wayyyy back.
Dunno if it's the best though for these tail boards because they will not be perfectly flat, but might do - dunno.
16 AWG and go longer - still big bump. I've done it.
This is not the best comparison because there is two weeks between these pictures and it’s Autumn. So leafes drop and nature changes color. But it’s the same place and same time of the day.
First picture is with stock Q8. Just cleaned dust and made sure that driver sits right. On the other picture it’s the same modes light. Just spring bypass with 22awg wires and changed to 100A FET.
Nature isn’t that pale what newer picture makes you think. The amount of light is just so ridiculous. Here’s also picture with BLF A6 on the same day with modes Q8. You can see that the grass is still greenish .
A nice earthing strap like the ones pictured in the link would be great. One could be cut and the cut end soldered to the upper end of the spring while the end with the lug would be secured with a brass screw that also fixes the board in place.
Finally off tomorrow... planning spring bypass and if I can find the screws locally I will get those swapped out.
Mine had to be 2nd batch as I've seen none of the mentioned issues.
Anyone know if 2nd batch screw holes aree threaded?
It just always seems a little funny all this work, not really for current, but for voltage. I mean voltage drop through the circuitry is what maybe 0.15V or something and the work is to get it down to 0.07V. It's not that there are big power losses in the wires, just you need that extra bit of voltage to get these LED's to draw harder (for a couple of minutes before the battery gets lower anyway). But if the xp-l2s have lower vf and don't fry... I wonder how the xp-l2 output would be without all the mods. If they're operating near their turnover, and they likely are, then you might see most of their advantage even without all the other mods. Of course they do happen to be one of the more expensive mods.
This is a crazy question, but DB do you still have a stock unmodded tube to connect to your xp-l2 light? I know, unmodded stuff in DB's hands, lol. Ok never mind.
I got around to doing a spring bypass yesterday. I removed the std inner springs and bypassed with 20 ga wire. I had already cleaned the driver board contact rings in the head and reamed the too small board holes out; which got the driver mounted flat with new 3.0M brass screws. The standard spring bypass with 20 ga wires netted an increase of 1322 lumens for 7139.
Tonight I finished a 1/16” thick copper plate for the tail, soldered in single springs and bypassed them with 20 ga wire. That netted an increase of 122 lumens for 7259. That was a lot of work for smallish return. A lot of work as I cut the plate by hand then filed it round to the scribed line. That was with steel screws, my brass ones are maybe a week away still.
Next, when I get to it, will be larger wires from driver to MCPCB.