The measurement relies on the calibration of the attiny MCU, which is known to have significant variation between units. Voltage measurement varies by about 0.1V and temperature varies by like 12 C.
… maybe? It would probably improve things a little, but I haven’t tried it. I have some thermal transfer foam, but it’s not easy to wedge it between the MCU and the pill, especially in such a tight space with wires in the way.
Exactly.
One-upped again. More lumens, more mAh, more bling. You really don’t know how not to customize anything. 
Sometimes I mess things up…
You guys are far more accurate/ articulate/ nerdy than I am so your results would be more interesting than mine. There is nothing I would like to change about the firmware except the inyoface LVP warning so for now don’t wanna pull the driver out
Just an idea dudes…
Now we’re all going to have send our D4s to DB Custom to get blinged!
That’s pretty easy to disable. Look around line 1600 or so and comment out the calls to BlinkLVP().
Not sure if this has been discussed yet or possible but here’s an idea: instead of stepping down to around 500 lumens, allow to user to choose the output level (current), depending on the ambient temperature of the environment being used this can be adjusted to suit everyone’s needs. It doesn’t need to be lot of options, maybe just 3: 1/1.5/2A
In my case I think the D4 can run comfortably at ~750lm in 25C ambient temp like my triple S2+. After seeing maukka’s graph and how slowly the output recovers after step down, I think it is better to dumb down the temperature regulation.
Thanks for the tip, but it is bearable for the moment :+1:
I haven’t entered the game of firmware development yet as I anticipate rapid improvements in certain areas within the next year or two, although what’s going on just now is kool as can be, I think my sincerest efforts will be more appreciated some time future.
Are those necessary for 20700 or are you just having fun?
I don’t think calculating temperature from Vf would help. I’ll explain via analogy.
Let’s say I’m blind and I want to go outside, but my guide dog is very photosensitive so I need to select an appropriately-dark pair of doggie sunglasses first. I can’t measure the brightness outside directly, but I do at least have a lux meter and a window, so I check that to determine which glasses to use. This is sort of what the D4 does now.
However, I also have a GPS clock which tells me the time, date, and location. So maybe I could calculate the average brightness at this location based on the time and date plus a reference chart for average seasonal weather conditions. This is like calculating temperature based on emitter Vf.
It seems like it would be less effective.
Great review!
Thank you.
I needed space for the longer cell, so I removed the spring from the driver and added 3mm with the brass spacer at the tail cap. The brass ring at the head is merely cosmetic to blend the gold and green. 
It’s still as short as it can possibly be… the spring in the tail cap is fully compressed when assembled.
The nitecore HC30 head strap works great! Groves line up perfect.
I like the D4 combined with sunglasses, this is one bright flashlight! :+1:
A heat shield between the head (of the flashlight) and the (human) head could be a cool touch…
I don’t know why I can’t see them without doing “View Source” but the links in Khas’s post #1213 are:
and
This light is an instant classic! I doubt anyone is on the fence with it, but if so… it’s certainly worth the money! Premium build/feel, fantastic UI, there’s nothing bad here.
Love that the ramp stops at the end of its travel rather than loop around again. Easy to start on low or last level used.
Some features I would pay more for: magnetic tailcap and a battery tube or tailcap with raised section for a clip, like the TK20 or Zebralights. A solid clip like that is worth the effort and money.
Because of the 3pc design the tailcap or battery tube could be sold as an accessory or replace the standard part for a different model.
It’s sold as a bright light but it would be nice if we could set set the max so it’s not even there in the ramp, set the max to whatever you want your brightest to be and that’s now the max level. Just like an alcoholic needs to keep alcohol out of their house, having that high at hand is so tempting. 12 steps clicks would be an appropriate location for setting it.
Either way this thing is a gem. The UI is quick and fun to use, much faster to find a level than I expected.
Kudos to all involved in development of this light!
question por favor. Can this light destroy itself in any way? What is the default on the thermal config? I turned my light on max and let it run. I counted to at least 30 I recall and there was no step-down. I turned it off, didn’t want to fry anything. It would have stepped down eventually, right? Thanks.
The v1 lights had a 45-second delay between step-downs, IIRC. V2 is only 4 seconds. If it’s v2 (has the reference blink in the ramp), it probably should have stepped down within 30 seconds unless it was using a weak cell.
What battery was used saypat and was it fully charged?
The step downs are obvious due to the high output and to where it has to get down to ,for controlling the heat. I get to around 12-15s before my 219c starts backing off, as even then the heat is still increasing fast. Very very clever ! Love it 