OK, thanks freeme - just got your advice, but sorry to say it's too late .
The light is a wide hold for sure, and awkward. The pic with the Coke can shows the body of the light to be 8.3% wider, but in real life measured, it's 9.75% wider . It's the only light I'm thinking of leaving the handle on - SRK size lights make no sense to have a handle on it, but this one does for sure. On the handle, it feels well balanced. The handle is better than I thought it would be - it does have a cheap looking rubber covering, but it feels pretty darn good - nice and soft but rigged and balanced.
There's a few things I did:
- XM-L2 U4 1C/20 mm Noctigon - nice fit, sanded down the 20 mm shelf center under the MCPCB to 1000 GRIT paper (smoothed out machined rings), GC Extreme under the MCPCB
- 20 AWG LED wires - not the min size, little longer, shorter than stock 22 AWG wires though
- removed the 5 diodes, replaced with 20 AWG Teflon coated wires (on furthest away pads, ran a longer wire)
- wired 'LED-' wire to a direct ground pad (no driver, true DD)
Did not bypass springs or mod the tail PCB at all - left as-is stock. Did not secure or add thermal grease for the pill top/shelf, also left as-is.
Amps: 5.15A across the switch
lumens: 1870 @start, 1812 @30 secs
throw: 296 kcd, measured at 5m (pretty solid reading, not even noticeable drop over 20-40 secs or so)
This is pretty darn good for not even bypassing the springs or adding jumpers on the tail PCB. One EFEST 26650 4200 cell measured 5.05A direct on the driver, so I think 4 of those cells in parallel help.
I'd say a FET DD driver should work out pretty well in here. I don't think the driver board traces are hurting much, but more could be done to reduce resistance.
For the lumens measurement, for me it's expected, since I measured just over 1900 lumens in a recent Yezl Y3 mod with a 5.30A tail reading, plus a UCLp lens. Possible I could measure 2000 in this light with a UCLp in there, with the springs bypassed. UCLp's have been giving me at least 5.0% gains, maybe up to 7%. For kcd, a 5% bump in lumens could be a 10% bump in kcd - it seems to be always higher, I've seen double many times.
So, lots of possibilities with this light. My raw kcd measurement could be 5-10% low (possible) because the shorter distance of 5 meters. A de-domed XM-L2 U4 1C could hit a min of 600 kcd, maybe much higher. I saw Racer86 reported a ~250 kcd on a TK61 mod with dome, higher amps but on a U2 XM-L2. I think this light has more potential than a TK61.
More pics for the mods:
Stock light beamshot on ceiling:
Stock LED and wires (22 AWG). The scratch across the plate is my doing - tool slipped when prying it off. A coupe of taps on a hammer to the edge of the MCPCB loosened it up good, the screw driver type tool to pry it up.
Retaining ring, and 'filler' ring below the driver:
Stock driver:
Closer look at the rings:
One thread shown here - I'd consider this almost fragile, careful not to mangle them. I'm afraid it would not last over many uses, hopefuly you don't need many though:
You can see the trace routes here. Must be a simple 2 layer board, like our OSHPark drivers:
Before sanding:
After sanding:
Diodes removed:
LED re-flowed and mounted:
22 AWG Teflon jumpers added: