With most of the gadgets and accessories and tools I buy, I look for ones that have flexibility in mind, whether it’s in how many jobs it can do or if it can work or survive in a pinch with a different add-on. I like flashlights that can use a few different cells or combinations depending on what I have at hand. I think it’s a relatively common mindset.
My only issue with 26650 and 21700 compatability is the springs. Will a shorter cell rattle? Will a longer cell crush?
I am looking to order the D4SV2 above, but do not see it listed on the site… Is it not on the new site?
D4SV2 is not a separate item. Go to the D4S and under the UI selection you can select Anduril with the RGB Aux LEDs.
I must be dense… I see only the selection of one color of aux led.
no amber color?
because they are smaller and lighter, better for EDC while still having great capacity
The aux led is under the UI option as mentioned by wolfstyle
Nope, amber option is limited to single colour only
I’ll have to weigh some… the 21700’s are 5mm narrower but also 5mm longer so the size issue should very nearly be a wash…
Edit: An 4500mAh 26650 Golisi Gold is barely a half ounce heavier than a 3000mAh Samsung 30T, so I really can’t see weight being a problem. True, the 26650 is almost a quarter of an inch wider, but it’s also the same measure shorter. So again, the differences are so small as to be very nearly unrecognizable. If you are so close to failure at carrying weight that a mere 1/2 oz could make or break you, then the problems you face are much larger than which battery selection to choose.
I understand that carrying a wider light, even less than a quarter inch wider, in silk suit pants might well be problematic, but then, anything of any comparable size would also be an issue. At which point, pocket carry would have to be dismissed and a belt carrier figured out. This light offers unparalleled output for it’s size, and it does that by using a readily available 26650 format. Granted, the 21700 is making inroads towards popularity in Li-ion cell choices but still it’s availability is much more limited than the 26650.
A neck light may well be of consideration if carrying a flashlight is problematic. Output and run time will suffer, but then, that’s what compromise is made of…
E07 is more EDC friendly than D4S and they have the same head diameter
But apart from the size, I sold all my 26650 lights and cells, I’m only keeping the ones that also accept 21700, I’m done with having a lot of battery sizes
It depends upon each person’s needs and how they use the light. In my case the 26650’s would be the last ones I would sell. Each to his own.
If I calculated this correctly, the 21700 cell is 83.36% of the 26650, yet the 26650 has 50% more capacity. So the 26650 is much more efficient for the capacity it holds vs it’s size. I probably missed something somewhere, usually do. 
Close, but not what I’m seeing.
Dropdown 1 - choose body color
Dropdown 2 - “IOS V3 UI” /or/ “Anduril UI (the same aux LED function as the D4v2) +$1.99”
Dropdown 3 - LED selection
Then some checkboxes for Aux LED colors.
Nothing here says the checkboxes are only for the Ramping OS V3 or that choosing Anduril gives you RGB.
So… Is the RGB AUX hardware in ALL new D4S but hardcoded to a specific color if you choose Ramping, or is a different LED/Aux board put in if you choose Anduril?
I see now, not just a cost to flash the new firmware, but that also includes the leds!!! Is not very clear on the selection page, since there is a place to select the aux colors.
If you choose Anduril in the 2nd option, just omit the third option. Otherwise it’ll be the old style single colour aux led if IOS V3 UI is selected.
Maybe Hank should just consolidate the single aux led options in the third option to the second one for better clarity.
True, the E07 is an excellent light, very slim and lighter than the D4S. However, I much prefer my D4S which I comfortably belt-carry in an old Thrunite TC20 holster.
The E07’s light weight means less mass to cope with the heat buildup while pumping out all those highly advertised lumens. Also, its extreme flood beam can’t compare (IMO) with the more focused projecting beam of the D4S. Even with SST 20’s the D4S still is the best combination of throw and flood of any light of its size that I have ever owned or heard about.
Without doubt, the D4S is a mini-Masterpiece!
this was a good starter for me so i added some comments to help me understand. What is the maths involved to get these integers in the PWM1_LEVELS? If I wanted to cut PWM on FET to 80, would my end value be 204? I see 128 for 219c on fw3a so 50 PWM (a bit conservative imo, so id like to increase pwm to 80%)
You may have missed the third dimension. 26650 is 26*26*65 and 21700 is 21*21*70. (with rounded corners). Volume is directly proportional to lengh and to a square of diameter. So 21700 is 70% of 26650. And capacity / volume? It may get close at certain discharge levels but most of the time 21700 wins.
For the volume of a cylinder you square the radius not the diameter
It’s just a matter of what constant do you multiply by later, pi or pi/4. So it’s directly proportional either way. And the constant goes away anyway when we express volume of one cyllinder as a fraction of volume of another.