I also wonder if the extra length is for some of the jumbo-sized 26650 cells out there or maybe with a sleeve to accommodate a 21700. Looks cool anyway.
Oh Lord! Where does it end? Yet another MUST HAVE light! :person_facepalming:
I expect the lanyard hole adds a few mm in length as well, glad to see that included!
Has anyone before in these 4700 posts actually checked this?
And where in the driver is this power (24W!) burnt off? 
(the light is fine after 10 seconds reverse battery contact).
That dark blue D4s looks awesome, but is that a new blue DRESS next to it as well? It looks shinier than the old Cyan color.
Oh wow 26650 D4!
Good catch.
Comparing manufacturer predicted beam specs for XP-G emitters, since both manufacturers have that emitter modeled:
Carclo 10622: 4.3 Cd/lm
Ledil C12885: 8.0 Cd/lm
Aside from a different optic, I wonder if the additional height also fits in any changes to the driver.
Given more PCB area, it seems pretty reasonable that additional 7135’s could be added, although that doesn’t add height.
To be honest, I’m not thrilled with the optics choice.
Not that Angie is bad, quite the opposite, but siamese optics are a proven choice that enables higher throw in the given size.
Angie with a rotated-pad-pcb is going to deliver a largely artefact-free beam. But personally I’d rather take a large few minor artefacts for a more pointy beam.
Still hoping they will come out with an aluminum 18650 battery tube for the D4 with knurling.
I hate smooth tubes and the Titanium version is too heavy for my pocket.
Holy crap, I want one.
Gonna start browsing for 26650’s in my vicinity.
I’ve got plenty of batteries just waiting for something like this. This is exciting. When can I get one? What are my color choices?
I guess that I’m the only one that is concerned about a 6A current and 24W of heat produced in the head when the battery is reversed. Say I put in a 30Q in a D4 the wrong way, close up the tail and do not check if it works and put it away. The sustainable power for this size light is about 8W so it gets hot fast. Perhaps some part on the driver will go at some point, will it break the circuitry or will it create a dead short?
I think that it would be a good idea for Hank to address this problem.
This is already known. I didn’t know it was “just” 6A instead of short circuit. Yeah, the light protects itself, but a dangerous situation is created if you leave the light like that. I think Hank already knows as well…
You are not the only one. It was already concluded by someone here that the reverse polarity protection was a flaw, was it toykeeper??
You probably should stop doing this 
You’re not the only one. I just don’t have a resolution except to consider this one of the reasons casual users should not buy this light.
I’m actually a bit surprised 6A for 10 seconds didn’t kill the light. The driver PCB is fiberglass, right? So it’s not going to take much heat away from whatever component is soaking it up, nor get that heat to the head very quickly so a user can feel the warming, indicating that something is wrong.
An early post of TK answering (before it was know that it didn’t have protection)
Since then, it was discussed some time ago, from here onwards:
Also, TK’s post after that:
Glad I never managed to put the battery in reverse position :person_facepalming:
We’ve pretty much all known since we were toddlers not to stick screwdrivers in wall outlets. We survive those little holes in the wall, perhaps we can put a battery in a flashlight the right way…
Yeah, Neal posted that on facebook.
I don’t think he was supposed to reveal it yet… I think Hank wanted to be the one to announce his new product. But Neal can only keep a secret for about 5 seconds. 
I’m hoping to do a review soon, if a D4S shows up in the mail. I’m going on a trip soon though, so I’m not sure if there will be time before I go.
I gave Hank some emitter suggestions, but I don’t know if he’ll do what I suggested.
Specifically, I told him he could avoid the heat issues of the 90CRI 219c by using 90CRI LH351D instead. And I told him people would really like a 4500K version using two 4000K and two 5000K emitters.
I hope he’ll make that happen, but I have no confirmation about it either way.
The reverse polarity behavior was noticed fairly early on, and I notified Hank, but I don’t think he ever fixed it. It doesn’t seem damage the driver, but it can damage the battery.
It appears to be fixed in the D4S. I checked a moment ago, and my DMM measured zero on a prototype with the battery inserted backward. The same DMM measures about 4A to 6A on a D4 with the battery in backward.
First, I just want to note that iamlucky13 currently has exactly 13 posts. 
About the driver though, it does have some changes compared to the D4/D1/D1S. I don’t have a production model yet though, so I’m not sure what all the changes are.
It seems one change is fixing the reverse polarity protection.
Thanks for pointing out the previous discussion, I missed it at the time but this afternoon I did find a short discussion without much detail on reddit.
But is there someone with enough knowledge of the driver to point out in what component(s) that heat is generated?
The reason I’m concerned is that I have build D4 with 2700K 90 CRI 219C leds for a lighting enthousiast, but who is new to flashlights. His first question, by email, when he received the D4 that I sent him (with battery and charger) was : “what direction should the battery go?”. He luckily had some sense that he could damage something by inserting it backwards but what direction is automatic for us is clearly not automatic for the rest of the world (he is a pretty smart guy). At that point I told him the right direction and eased his mind that the D4 was reverse polarity protected so nothing would have happened anyway (so later I had to update this story for him).
Thing is that the D4 takes such good care of the battery and the heat by means of the firmware that I did not expect it to have some silly hardware flaw that instantly makes it a dangerous light for anyone not knowledgable about the background of this light (including me even so it turns out).
The guy is smart enough to after the update use his D4 now in a safe way and so am I.
I’m glad to hear that