TK's Emisar D4 review

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Agro
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Would knowing actual LED temperature help thermal management?
I ask because I just learned that you can calculate it from Vf. It would require different firmwares for different lights though.

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djozz wrote:
Coincidentally, Agro just posted the same need for a direct access to the maximum thermally stable mode. Smile
Best solution is probably a firmware update.

Change the UI as follows:

  • 3-clicks – shortcut to 2.5 amps … This is similar to what DrJones did with his lumodrv ramping firmware. Triple-click is easy to access and is helpful to use as a shortcut to another well-used mode. Another option is maybe set this at 3 amps. It might still ramp down at 3 amps but probably not for a few minutes and probably not by much.
  • 4-clicks – shortcut to battery tester
  • 5-clicks – shortcut to tactical momentary

Everything else can stay the same.

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charles lin wrote:
X3 wrote:
What is this clip ?

Fuzzylogic wrote:
Can I ask what clips you are using here? They seem to be a much better length than the convoy ones.
Yes, the clip is great quality & it fits D4 perfectly well. The only place I know sell this clip is from Taobao

Link does not work…
winspiration
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Does anyone have an estimate as to how long each led can run on turbo before it’s thermally regulated? Or a discharge curve as to the amount of total runtime on its highest setting? I want to choose a flashlight that is amazingly bright but also practical. If it can only sustain turbo for a couple of seconds, then it’s not the light for me. Thanks for your input.

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winspiration wrote:
Does anyone have an estimate as to how long each led can run on turbo before it’s thermally regulated? Or a discharge curve as to the amount of total runtime on its highest setting? I want to choose a flashlight that is amazingly bright but also practical. If it can only sustain turbo for a couple of seconds, then it’s not the light for me. Thanks for your input.

Depends on cell and ambient temperature, but for the 219C it’s 15-20 seconds (from cold) on turbo (before it starts to step down).

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The D4 can only sustain turbo for a couple of seconds, it varies with the emitter choice but very short it will be! Amazingly bright in this size will just get amazingly hot, whichever flashlight you choose, and the D4’s well-working thermo-regulatation is as practical as such a light gets.
There’s more settings than just turbo though, still pretty bright and also sustainable, actually for the size the D4 is build very well thermally (i.e. better than an S2+)

You may want a bigger light though, much more heat capacity and heat-shedding surface area.

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Forgive my ignorance, as I am not fully comprehending the output graphs posted in the OP, but what is the max sustained lumen output of this light? Am I reading it correctly that it’s only about 150-200 lumen? This can’t be…

In turbo, it seems to be dropping like a lead balloon immediately upon engaging, which, if it’s really about 4000 lumen, that’s understandable, but at what lumen level does it level off?

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Pete7874 wrote:
Forgive my ignorance, as I am not fully comprehending the output graphs posted in the OP, but what is the max sustained lumen output of this light? Am I reading it correctly that it’s only about 150-200 lumen? This can’t be…

In turbo, it seems to be dropping like a lead balloon immediately upon engaging.


Like other lights of comparable size (think S2+) D4 can sustain about 1000 lumen without breaking, but it will be way too hot to touch then. I can confirm CRX’s test that between 500 and 600 lumen and hand-cooled it is sustainable. When outside with airflow all flashlights can run brighter without overheating.
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Charles Lin, Efest makes a dark purple 18500 1000mAh cell that’s high discharge… it gives me some 3400 lumens on my scratch built Ti/Cu Quad and 3200 lumens in my Mec-Army P16 Quad.

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Remember that the temperature regulation works differently on different batteries. The VTC6 for example gets so hot so fast that the regulation corrects it much more than on the Aspire for example.

Here’s both cells on turbo with the temp limit set manually to 43°C.

Sampled every 1/3 second. I’ll overlay output on those tomorrow.

On video, without temperature calibration (subtract 3°C):
VTC6

Aspire

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Always a great pleasure to read your interesting and well-presented data, maukka! Smile

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Awesome vids maukka, you are da man Thumbs Up

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Another night, another walk, another couple of notes:
1. If I have the light off, with some low mode memorized. 2-click to turbo. 1-click to turn off. 1-click to turn on. Result? It forgot the low mode and starts with Turbo. That’s unnecessary, if I want turbo again, I can 2-click again.
2. I have a light on some high mode, want much less. Solution? Twist the tail cap back and forth, turn the light on. Result? Nothing happens. You need to wait until it double blinks and then wait some more until you can turn it on.
3. It would be more noob-friendly to blink out battery capacity (scale 1-10) rather than voltage. Could be slightly off with 4.35V batteries, but there are few of them…
4. Thermal regulation really dims it down. It’s way below 350 mA after turbo and takes very long to recover. It’s better to reset it to 350 mA than wait. That’s 219c/VTC6.

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djozz wrote:
Pete7874 wrote:
Forgive my ignorance, as I am not fully comprehending the output graphs posted in the OP, but what is the max sustained lumen output of this light? Am I reading it correctly that it’s only about 150-200 lumen? This can’t be…

In turbo, it seems to be dropping like a lead balloon immediately upon engaging.


Like other lights of comparable size (think S2+) D4 can sustain about 1000 lumen without breaking, but it will be way too hot to touch then. I can confirm CRX’s test that between 500 and 600 lumen and hand-cooled it is sustainable. When outside with airflow all flashlights can run brighter without overheating.

+1
I’m no expert here but have a few lights of all size and although i may have not argued as clearly as djozz, i would have said that this kind of small light should not run much higher then 600 lumens because of heat dissipation – as of today. The 3k/4k lumens extravaganza is just that, a quick burst if need be but only for a few seconds. No magic involved here.

Now, hopefully, one day in the not too distant future… we may have more efficient leds that produce very little heat… and this kind of minor miracle may last much longer then we dare imagine. Pure light, no heat, that would be intense. Could you have imagined a D4 just five years ago? Can’t wait to be ten years older! Evil

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patmurris wrote:
Now, hopefully, one day in the not too distant future… we may have more efficient leds that produce very little heat… and this kind of minor miracle may last much longer then we dare imagine. Could you have imagined a D4 five years ago? Can’t wait to be ten years older! Evil

- The year 2027 -

“Wow, I can’t believe this EDC light steps down to 10000 lumens only after 10 minutes…”

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winspiration wrote:
Isn’t protected safer though?
imo No, because the light already has built in protection, read post #1:
ToyKeeper wrote:
This driver also has low-voltage protection. At 3.0V it’ll drop to the lowest level, and at 2.8V it’ll shut itself off as far as possible.

winspiration wrote:
Does anyone have an estimate as to how long each led can run on turbo before it’s thermally regulated?
About 30 seconds at which point the light drops to 10% output…
Look at the post below by CRX.. it depends partly on what thermal regulation setting is being used

Pete7874 wrote:
what is the max sustained lumen output of this light?

In turbo, it seems to be dropping like a lead balloon immediately upon engaging, which, if it’s really about 4000 lumen, that’s understandable, but at what lumen level does it level off?

See post 958 below, to get some idea. It has been suggested that 600 lumens might hold steady. afaikt there is no way to set the light to 600 lumens, or any other specific lumen level, unless you have a light meter.

you Can set to a NoPWM mode of about 150 lumens:
Post #1

ToyKeeper wrote:
Loosen and tighten the tailcap, then click: Turn on at the highest regulated mode (~135-165 lm).

Post #958

CRX wrote:

"High CRI Lights for Sale":https://budgetlightforum.com/node/75426

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maukka wrote:

Thanks for the videos.

Would be great to see the lumen ouput overlaid on these graphs also Thumbs Up

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Hmm… So, if you start at a lower level, what is the highest output it can sustain for a couple minutes? 600 Lumens sounds low? So after two minutes my Zebralight SC600 II would be brighter? I see H2 on the Zebra is about 670 listed output, so maybe around that level?

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DB Custom wrote:
Charles Lin, Efest makes a dark purple 18500 1000mAh cell that’s high discharge… it gives me some 3400 lumens on my scratch built Ti/Cu Quad and 3200 lumens in my Mec-Army P16 Quad.

Yes, I know Efest 18500. However, compared to 18650 vtc6/30q/GA & 18350 Aspire; I expect a good 18500 size battery will do High Discharge: 10~15A, Capacity: 1300~1500 mAh.
patmurris wrote:
Link does not work…

The link works on my side…….Try copy & paste
https://world.taobao.com/item/45807591464.htm?fromSite=main&_u=t2dmg8j26111
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Agro, all your notes are confusing.
If you have implementation ideas perhaps you should just offer new code, maybe then a simple reflash would allow others to sample your idea of perfection?

I know several here have already done due diligence to get the D4 to where it is today, I like mine and will be the first to admit I’m still playing with it and learning.

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20 amps running through this small light body, in the palm of my hand… Should i be worried?
How much of a magnetic field would that produce? Would it affect a compass up close?… How about PWM induced field variations?

Agro
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DB Custom wrote:
Agro, all your notes are confusing.

Could you explain what do you find confusing about them?

DB Custom wrote:
If you have implementation ideas perhaps you should just offer new code, maybe then a simple reflash would allow others to sample your idea of perfection?

I would be very happy to do it. Typically these are not major changes. But I have no hardware to be able to reflash the light myself, so I can’t check my changes.

DB Custom wrote:
I know several here have already done due diligence to get the D4 to where it is today, I like mine and will be the first to admit I’m still playing with it and learning.

They did amazing work. But there are (mostly trival) wrinkles here and there and I do what I can to smooth them out – give feedback to the makers.
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Maukka, are you using the 219c for your tests?

If you are, do you have any explanation why mine steps down in under ten seconds using the vtc6 and lower ambient temperature than you? Should I check if the thermal paste is badly applied on mine?

Btw, I haven’t fiddled with the temperature limit, so it’s still at 45 degrees.

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Just did a little test underwhile browsing BLF. I put a fresh 30Q cell in my D4 and using my sphere I set the output at 550 lumen (my D4 now has 3500K 90CRI 219C’s so it is comparable to the stock 219C’s at about 600 lumen). I started hand-cooling the light. I must say I had a rough time, I had to swap hands every minute and it was still an unpleasant temperature, but it really was sustainable, after 12 minutes I decided that I could just go on like that and stopped the test. The output had dropped to 500 lumen then.

I did it again (start at 550 lumen) with a more depleted 30Q (3.7 V at start) and now it was a bit easier, but not much.

So yes, 600 lumen as the maximum sustainable temperature inside at room temperature seems about right. But without hand-cooling it will be lower (TK’s temperature feedback makes it about 300/400 lumen, as read in CRX’s data)

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Excellent test Djozz,

But what does it tell us?

Would the D4 be “improved” if:

It were 4 – x mm longer and had a heavy shelf behind the emitter? (would a longer light be a problem?)
Is this telling us that this light is a great candidate for real cooling fins?
Not an expert here but are there other drives that can run the light with less heat (or brighter for the same heat) thermal efficiency?

I understand the meteor m43 has a more efficient driver arrangement, could something like that be a “good” option for the D4?

And My personal soap box, I say we need a “just right” sized light between the 4×18650 MeteorM43 and the 16340-18650 D4.
I’m thinking 26650 with 6-9 emitters. How much meat and fins and with what type of driver should it be specked with?

Please chime in!

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
Ajaan Lee Dhammadharo)

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Ronin42 wrote:
And My personal soap box, I say we need a “just right” sized light between the 4×18650 MeteorM43 and the 16340-18650 D4. I’m thinking 26650 with 6-9 emitters. How much meat and fins and with what type of driver should it be specked with?

How about 3×18650 with 7 emitters? Evil

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Ronin42 wrote:
And My personal soap box, I say we need a “just right” sized light between the 4×18650 MeteorM43 and the 16340-18650 D4.
I’m thinking 26650 with 6-9 emitters.

Sounds like you’re describing DQG Tiny 26650 III… 2,500 lumen on turbo, and it’ll run at 900 lumen all day long.
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In thinking about TK’s now famous quote

“Basically, thermal regulation is rather unpleasantly like trying to steer a fast-moving cow around a hairpin turn on an icy race track. While wearing someone else’s glasses.”

I have a dumb question/idea.

If it is so hard to manage (thermal management of the X where the sensor is placed near the emitter) and as the gating interaction seems to be the ability to hand hold the light (as opposed to frying the emitter). What would happen if instead we just thermally managed the body/head of the light.

When Light gets X hot (subjective to the hand) then use that temp as the target temp. My hunch is this will make the management and both easier and more accurate.

Then all we have to do is try to steer a fast-moving cow period and (“around a hairpin turn on an icy race track. While wearing someone else’s glasses.”) goes away.

Am I crazy?

say something nice

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
Ajaan Lee Dhammadharo)

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hIKARInoob wrote:
Ronin42 wrote:
And My personal soap box, I say we need a “just right” sized light between the 4×18650 MeteorM43 and the 16340-18650 D4. I’m thinking 26650 with 6-9 emitters. How much meat and fins and with what type of driver should it be specked with?

How about 3×18650 with 7 emitters? Evil

Hard to tell what’s optimal, but that is definitely an option.
What it DOES NEED is active cooling of some sort, so it can maintain an output of at least 2000+ lumens indefinitely.
Make it as small as possible and don’t forget high CRI.

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hIKARInoob wrote:
Ronin42 wrote:
And My personal soap box, I say we need a “just right” sized light between the 4×18650 MeteorM43 and the 16340-18650 D4. I’m thinking 26650 with 6-9 emitters. How much meat and fins and with what type of driver should it be specked with?

How about 3×18650 with 7 emitters? Evil

I really like your idea. I always though that 3×18650 fit much more comfortably in the hand. The number of emitter I leave it to the experts, but 3×3 is 9. Sort of like an in-out burger (for those who don’t know their best seller is a “double-double”) so maybe a triple triple is what is needed for the Goldy Lux light. (pun intended)

I have always thought that 4× 18650 light were just a bit large to actually want to carry (sure it can be done) but out of our flashlight actual carry minutes what percentage is from 4×18650 lights? My hunch is it is out in the long tail of the bell curve.

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
Ajaan Lee Dhammadharo)

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