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.
It’s not that there is a fixed amp ceiling… the value is determined by a combination of cell type, cell voltage, cell sag, emitter Vf, heat, and the resistance between them — wires, springs, etc.
With one XP-L emitter, direct drive on a full 30Q pulls around 6A or 7A, which makes a nice turbo mode. With one 219c, direct drive pulls 10+ amps and kills the LED. With four 219c emitters, direct drive pulls about 20 amps divided four ways and it again makes a nice turbo mode.
However, if I were to connect eight XP-E2 red emitters, which are 2V LEDs instead of 3V, the same cell could probably push 40 amps and kill all eight emitters. They can only take about 2A each, and they would be getting more like 5A.
Or if I were to short the cell with a thick copper wire, the battery would probably release many more amps and start on fire. If it’s rated for 40 “pulse” amps, that doesn’t mean it can’t put out more than 40 amps, or that it will put out 40 amps before dropping down… it means it can withstand that much current for brief periods without exploding. However, a fire could start if the current is sustained too long.
When you think about it like that TK, isn’t it surprising I haven’t had a flashlight turn into a small bar-b-que pit yet? (knocking on wood)
I’m surprised we’re not seeing wearable power supplies yet.
You could wear a lot more batteries than you can fit into a handheld light source.
My first-run Emisar D4 is finally running the latest firmware. Well done, TomE and TK! :+1:
I just got back from a hike in a dense forest. I had a Zebralight H602w headlamp mule steadily burning at 330 lumens while walking the trail. I used an X6 running Bistro to see down long stretches.
At trail junctions, I used the Emisar D4 in momentary turbo mode. Perfect for lighting up everything for a quick look around.
I also discovered that the D4’s momentary mode is memorized even after a tailcap lockout. 
So if I drop it in a cup of water will it heat up enough to make instant coffee?
Just tried the 18350 tube.
This thing is comically tiny for the amount of light it produces on 18350. 
A 219c D4 is on my way… Please refrain from making the wait worse! lol!
I haven’t received it but i already need another one…
One thing i’ll do for sure is to line up the D4 shorty (2017) with a DQG Tiny 26650 (2016) and a good old SRK triple (2013)… and consider they put out about the same amount of light. What’s next? A 2K lumen keyring light? :smiling_imp:
anyone? mine still processing.