How about this: XP-L is more efficient than XM-L. But if you run a lot more current through an XP-L, then it gets hotter than an XM-L, although XP-L is more efficient. Back to D4: an emitter can be more efficient than another, but due to different Vf it gets hotter than the less efficient emitter.
After your discussion, I’m more confused than before. 
Will I go wrong if I choose Nichia or is it better to choose Xp-g2?
Which holster do you recommend for this FL?
Impressive.
I stand corrected. I actually looked at fonarevka PCT. There, 219c has quite high Vf curve. In Texas Ace’s tests that’s entirely different matter. I guess I should make major amendments to the predictions above.
Got it now.
BTW, another prediction:
Once temperature control kicks in, XP-G2 will be brightest, XP-L close second (maybe first actually), 219c last.
How do I know? The measurements quoted above. In this torch, XP-G2 makes the most light at 350mA, the highest regulated level of current. Results may vary at other currents.
My quick measurement also agrees with djozz’s tests. The test shows more lumens from XP-G2 for the entire graph, compared to 219c, until the point where the current exceeds what XP-G2 can handle. This is defining efficiency only in terms of lumens per amp though, not lumens per Watt. Because lumens per amp is what matters on this type of driver.
XP-L HI isn’t on that graph. Normally I’d expect XP-L (domed) to have the highest lumens per amp, but perhaps the XP-L’s advantage doesn’t start until it gets to higher currents? Or maybe the HI’s lower bin eliminates the advantage? Let’s check the measurements… Going from djozz’s test data, I see…
- XP-G2 S4 @ 1A: 440 lm
- XP-L HD V6 @ 1A: 490 lm
- XP-L HI V3 @ 1A: 400 lm (estimated)
- Nichia 219c @ 1A: 390 lm
But at higher current, XP-L HI may be more efficient…
- XP-G2 S4 @ 5A: 1330 lm
- XP-L HD V6 @ 5A: 1820 lm
- XP-L HI V3 @ 5A: 1486 lm (estimated)
- Nichia 219c @ 5A: 1200 lm
The estimated HI values are the HD values / (1.07 3), since Cree specs each bin as 7% brighter, and HI is three bins lower.
It looks like the intersection point is at about 2.8 amps or ~980 lumens. … which I think works out to about 11 amps and 2850 OTF lumens in this light. So, in the D4, XP-G2 is likely the most efficient up to about 2850 lumens, and then the XP-L HI is the most efficient for higher levels.
XP-G2 has the highest Vf though, so it’ll have the most sag on a low battery. Nichia 219c should have the least sag.
For practical purposes, they’re all good choices… so pick whichever one has the tint you like. Tint is much more noticeable than the other emitter differences.
In my D4 with the stock XPG2 emitters, with the light cold and then turned on to max turbo I could go maybe 20-25 seconds before the head gets too hot to touch. Now that I’ve swapped in 219C emitters I can go 13-15 seconds.
I’m still undecided if I want to leave it like this. I like the tint, output and high CRI, but it gets super-hot way too fast.
I compared it side-by-side with a Sunwayman I’d modded into triple XPL HI 5A2 running on an 18500. With both lights cold, the D4 Nichia produced more light, but the XPL HI triple had more throw.
After a full minute of operation the D4’s temp regulation had dimmed it to maybe 10% power while my Sunwayman without temp sensor but with timed stepdown to 50% was still touchable and produced noticeably more light.
It may just be XPL HI is a better choice of emitter for this kind of hot-rodded light.
I’m not sure if I want to try swapping in some XPL HI into my D4 tonight or wait until my next D4 arrives and do it on that one.
One possible solution to this problem would be a firmware update: Allow the user to manually cap the maximum output of the light. It wouldn’t be as bright, but might be more practical.
In the measurements I’ve seen, 219c has significantly lower Vf at all current levels, compared to XP-G2 or XP-L.
For example, at 5A, djozz measured:
- XP-G2: 4.05 V
- XP-L: 3.90 V
- 219c: 3.43 V
It can also apparently handle a ridiculous amount of current before it pops, which is fortunate since the low Vf allows it to draw so much more current. But with the highest current and the lowest efficiency, it’s going to make the most heat.
This is probably correct, and an interesting way to look at it. XP-G2 should have the least heat, and the most lumens after regulation stabilizes.
Now I want three D4s so I can have one each with XPL HI, XPG2, and 219C.
Would it be worthwhile replacing the XPG2 with XPG3? Would it be brighter or run cooler?
Brighter and run hotter, the xpg3 has a way lower voltage than xpg2, very close to the 219C.
Brigher, hotter, floodier.
Why 219b 9050 version is not available 
Why 219c 5000k 90 cri version is not available
Any expectations for new versions?
Stuck between S41 219b and D4 219c. I think with FW3A, 219c 83 cri will be more unnecessary than high cri 219b.
So how about double the output.
Shadow TC-750X, modified Shadow BL-20, MAXToch DX21
I’m certainly missing something because it looks like the 219c is ill suited for DD and will be brightest will a half full cell?
I wouldn’t complain if there was a 219b 4750K 92+ CRI option. It’s my favorite LED tint. Because of this, I have a bunch of 219b lights, including triples, some of which are FET+1.
But the 219b tint isn’t as nice on direct drive. It looks great at up to 1.5 amps per emitter, but it gets colder and less vivid when the current is maxed out. On a hotrod like this, the 219b’s tint advantage doesn’t mean as much. Output would max out at 2400 lumens or less (probably 2000 or 2100 lm), and the tint would be diminished above ~150 lumens. For optimal 219b tint, a different light might be a better choice.
There are six emitter options, though, for a wide range of preferences. The XP-G2 3D option is very, very close to a 219b. And the 219c is very nice too, just slightly cooler than 219b and not pink.
The D4 is already pushing 20 amps from one cell. Doubling the number of emitters isn’t likely to increase output very much. The limit here is mostly the battery, not the emitters.
Cell voltage sags under load, while emitter Vf rises under load. For direct drive, turbo is where the two curves meet.
With one high-amp battery and one 219c emitter, there will probably be magic smoke. The curves meet at like 12 amps. The 219c’s Vf is low enough that a high-amp cell can overload the emitter. Not a good idea.
With one high-amp battery and four 219c emitters, it works out fairly well. It pulls about 20 amps, or 5 amps per emitter, which puts the peak power level slightly on the safe side of the emitter’s peak output.
So, it depends. The 219c can work in direct drive, but only with the right hardware configuration.
IIUC the amp ceiling is determined by the cell, and as of now it would be around 20A… which spreads well on four emitters.
Thanks for the explanation, it makes sense.
BTW: some cells are advertised with 40A+ on ‘pulse’ - not sure how long that is. Could such a cell toast the leds at startup?
My comment was more a “can we push it any further jest”. Only the very specialized 26650’s or 20700 could push the amps needed. Heat has already been the villain here. Still I see a Hepta light after these quads being tried. This tiny format has so greatly exceeded a practical use that it’s become the “Fun factor” most here are hooked on. I’d love a quad XHP-35 on a pair of 20700’s side by side with a booster drive. Nothing practical there but great fun factor. What I love about these styles of lights is after it’s made all the hobbyist and would be engineers on these forums get a crack at it. Slowly we discover:self thickness, heat sinking, driver efficiency and all the other tricks to squeeze ever ounce out of it. While other substitute better batteries, LED’s, drivers and copper boards. I’ve seen silver plating and diamond dust potting just for a few more lumens.
Do you all realize this forum has pushed the original P60 LED at 80 lumens to over 4000 on an XHP-70, made 12,000 lumen soda cans the actual size of a soda can. Created drivers and programming that’s used by manufacturers. Being such a P60 fanboy, I’d like to see these morph into dropin’s. Until then I’m waiting for one of these in the mail.
Well said TS, and after receiving my D4 xpg2, the fun factor is certainly at play. Thanks to TK it’s actually safe to use also!
Just for grins… XP-L W2 2B (XP-L2?)
This is the only emitter in all talked about here that is capable of exceeding 2000 lumens all by itself.