Got my first D4 in a couple of weeks ago. Ordered from intl Aug 31, got it about three weeks. Went for a grey (green not in stock) with XP-G2 S4 5D 4000K partly for cost, but mostly since the XP-L and Nichia were only available in 5000K at the time (5000K is too cool, if I have a choice, and 3000-3599K is ideal). Also, I have no interest in pounding Nichia 219s to death when I have a nice Jaxman E2L 4000k triple (2.1A?) if I need a lot of high CRI light.
Lot of info in this thread about XP-L and Nichia, very little on the XP-G, and even less on the 5D, even though I think there was a list where it came in 3rd or 4th most popular. Bought a clamp meter that cost almost as much as the light, which makes both items a great deal. I get a bit over 11A with fresh 4.2V 30Q or HG2, and about the same with a 4.1V Sanyo NSX. Suits me. I stay under 3A per emitter, and itās still total overkill on turbo: eye searing (closed eyes), skin burning (the beam or the light), and fire starting (if the paper is a dark color). I get 11s turbo before 1st stepdown using a 49C thermal setting. 59C, but the light reads about 10C too high. The outside of the light gets to 52-59C, depending on conditions. Got 8A with a generic 2500mAh cell, 8-9A using a 20A DMM with short 10awg leads and internal 10mOhm shunt.
Iām a total Zebralight nut. SC600, mkIII HI, mkIV Plus, SC60,62,64. Not counting the AA ones, two of which are high CRI (the XM-L is the worst white-wall tint Iāve ever seen, so I can see why Emisar isnāt using Cree for CRI). I love everything about them except for their complete disregard of my battery terminals in the SC52,53, and 64. The 63/64 really should use the D4ās tail spring. Iād suggest it to ZL, but Iāve already complained multiple times about their battery abuse, and I have to believe they know about BeCu springs. In the meantime some 0.1mm copper foil on the abusive spring suffices.
So, I just got the D4 because it was a cheap experiment, and so many people raved about it. Iām almost embarrassed to say, like so many in this thread, that the ZLs are all on the shelf. The SC64 is a much better EDC because of the size and the clip (even if the clip does wiggle a bit), and the Plus is effectively as bright as the D4 with much better efficiency, temperature control, and moon modes. But, the D4ās tint is so much nicer, and the UI is so much fun. Reminds me of my old keychain Photon Freedom, a SotA 10 lumens back in the day. I donāt know if itās the tint or the UI thatās more of a factor, or the feel in the hand, but I really love the D4. To throw in the iPad-size work bag, I found a LED Lenser PX20 (red/white LEDs) holster fits the D4 perfectly. Shouldnāt need a tailcap lockout, but it really would melt the black nylon if turbo came on.
So, I love it, but whatās a one-sided review. Soā¦
To gripe, Iām not a fan of the well-executed but too-simple driver. ZLs efficient 12V boost driver is incredibly impressive engineering. The D4 is just, well, something that can be easily put together with off-the-shelf parts. The mechanical part of the design, especially the springs, took some ingenuity, though. Maybe as much as ZL, given the price. And the springs are flat-out superior to ZLs struggle with too-stiff springs and pogo pins. I donāt know why thatās given them so much trouble. The body design is basically a ZL copy made easier and cheaper to manufacture. Iām not griping about the $35-40, though. $90-100 ZLs do give me pause, $60-70 ones are worth it.
For the UI, the only real complaint for practical use, is that it memorizes turbo if you shut it off in that mode. I like the three blinks in the ramp, and really donāt get the analogy with a car where the engine stutters at efficient RPM. Itās not a car. It has nothing the least bit in common with a car. Even calling it a āhot rodā only makes sense to me in that it is cylindrical and if you run it long enough on high, itās like holding on to the wrong end of a torch (the flaming kind). Cars have lots of controls and indicators. This has a button and a light. And, if weāre going to gripe about questionable turn-off times, the dark time to turbo after a double click while on makes a lot more sense to me. The double-click event and timeout explanations cover / justify that, though. The tactical mode is completely pointless, since a couple of flashes and itās off doing something else. Iād ditch it entirely and use 4 clicks for lockout.
Iām not planning to get another D4, but 9/25 I ordered a green D4S with 4000K XP-L. Iād have much preferred 21700 or 2x18650 to 26650, but it looks like a comfortable size. And IT HAS AUX LEDs. I wasnāt even considering it ātill I saw a picture with the cyan pseudo-tritium, after that I couldnāt order fast enough. I could see maybe another D4 if green or another smooth color comes out, like purple, and if some other 4000k (CRI?) option comes out. Nichia is just a bad match for a linear driver, but maybe XP-L, preferably Samsung. Donāt expect either, any more than I expect a 21700 tube for the D4S.
So, the light and reading all of this thread have been a ton of fun, thanks BLF.
I agree the xpg2 5D is the best emitter choice for the D4.
If possible Iād love a link to a post with a current circuit diagram and/or a list of current component values. Catching up on the FW development thread has helped and I probably have a good handle on the changes that have been made but it never hurts to be sure. The high quiescent current of previous designs is actually what kept me away from e-switch lights in the past. I just wasnāt comfortable with a light being dead in a handful of weeks if I failed to do a mechanical/electrical lockout.
Rather than continue to derail your review thread Iām going to try and get my thoughts together over here: 
