Yes all of that is understood. Thanks anyway. :THUMBS-UP:

A lower current cell is also of benefit for a linear driver, reducing the driver's dissipated heat.

There are some duper low price deals for high capacity low current cells in AliExpress. Asked Henrik to get some reviewed, by the way.

Quite low Vf, so low it could also work very well with an efficient buck driver like an LD-29 fed with single cell. Stack an R050 over the stock R025 for 4.5A maximum drive current.

Sofirn sells the C8S host with 20+mm driver hole and smooth reflector, I wonder what sort of throw performance would that net with the white flat. 200KCd?

Cheers :-)

For people got confusing about different performance L4P and Djozz got of their tests.

Djozz got best performance at 4.8- 5A while L4P got it at 5.75A.

L4P explained why they got different readings: “Excess solder could cause that when power density is high like with this LED. Also, I’m using lead-free solder which has a little bit better thermal conductivity.”

I did my own re flow and I used very thin layer of solder paste we mostly use here (that cheap budget mechanic solder paste in syringe) and I got similar performance to L4P test.

Yes I also find that confusing but I know that my test subjects Osram white flat performs as in L4P test. And since I am testing it for more than month in fet dd setup I know it is robust emitter that will work without any issue with low current 18650 cell like LGBD1 and that it can even survive abusing with high current cell like Samsung 30Q but I don’t recommend that to anyone. Why would anyone want to run emitter on 7A if it has best performance on 5.5A?

So yes. Barkuti is right. If you want to be worry free get regulated drivers, but if you insist on FET DD be very careful and use low current cell or you could fry something out :slight_smile:

New tests:

52KCd in Godmes T01 (14500)
118KCd in Olight M22 (30Q)

Original driver in both. The main difficulty of this led is propperly focusing. It was impossible to focus the TK61 (600KCd max) and Warsung MX900 (83KCd max)


FYI. For the record, I’m not trolling anyone here, Jack, nor am I trolling anytime, period.

Other readers didn’t exactly agree with you 1:1 on every single technical point, observation, or at times confusing or contradictory comments you’ve made until you further clarified your comments but that doesn’t mean they obviously don’t understand or didn’t read. That includes me.

Look at your Post #122 as an example. Even you admit there are seemingly confusing elements involved.

All I poised was that can the Osram KW take relatively short bursts from high current cells on highest draw mode without harm if for whatever reason I need/wanted to do so. The point being this led isn’t apparently going to immediately fry with a short or even long burst from a high current cell. Is it optimum? No. Is it recommended by you? No. But again to be clear I don’t disagree with your initial comments about this led performing best with a low current cell. Totally understand.

Congruently I also surmise I can still put a high current cell behind it if I keep it away from operating on essentially turbo mode. But it’s not absolutely essential because it can take the abuse as you said. So it’s really not a safety issue according to you, right? This led apparently isn’t going to melt, fry, or cause a fire with a high current cell, right? It’s really a better performance issue, right? No problem there. I fully understand. Ergo, I’m not trolling.

You see there are times and situations when and where I foresee I may not happen to have a low current cell on me when this led happens to be in an empty light that I need to use for whatever reason.

It’s not going to definitely harm anything according to the long term results of your high current testing other than it’s just not needed for best performance so why do it? Agreed.

And again, fully understood. So am I a troll?


PS. Am I correct that English is not your first language at Location ‘X’? I guess I have trouble deciphering exactly what you’re saying at times. Maybe moreso the syntax.


Well you are wrong. Again, I’m not trolling. I kinda suggest you quit going there with that deal. It’s better that you understand you gain nothing by name calling or trying to paint someone negatively so that you try to look superior to others.

Now reread edited post #124 to better understand where I’m coming from.

Performance discussions about leds used in flashlights, however heated, however annoying, however one seems to not understand the other, are not trolling.

A troll has no opinion, has no conviction, does want to convince someone else, he just wants to mess up. This not going on here.

Well, at any rate, the BLF Rules prohibit fighting, and regardless of a user’s opinion or motives, this is always the best course of action:

I’ll lock this thread for now. If there’s something else to add the technical discussion please PM me and I can re-open it after tempers calm down.

Thread re-opened. To those who participated in the argument that broke out, please go back and delete those posts. Thanks.

I read the Texas Ace test that showed that a cheap thermal paste is just as good as a top one for flashlight use.
But Osram LEDs are quite vulnerable to bad thermal transfer. I have GD900 and I wonder if it’s worthwhile to invest in something better?

Arctic MX-4 won’t let you down.

Cheap thermal compounds tends to dry very fast.

Very worthwhile to invest cause you don’t want weak link in your modd or build.

If you have two copper surfaces, liquid thermal paste is the best way to go (it’s much, much better than any standard paste). Otherwise something like Arctic Silver 5.

The flatness of the surfaces will make the biggest difference though.

In my experience GD900 works rather well and is quite sticky.

Besides GD900 and way price-ier there's GD900-1 and then GD007


If you want to use liquid metal, conductonaut is the best option.

If you want regular thermal paste, I use MX-4 because it’s one of the best but also has other advantages like being cheap for a large tube, being easy to clean off, having low viscosity, etc.
Other thermal pastes that are good include NT-H1, kryonaut, IC diamond.

Thanks for the answers. I may try better GD pastes one day.

Frankly, I forgot that the first light I’m going to try has a brass pill. So I think liquid metal is an option?
Though if I go this way, my pick will be galinstan as it’s way cheaper than the other options.

But for alu this doesn’t work.

GD-900 that I have is only marginally worse than MX-4. Definitely the difference is not worth the investment.

If I were to switch, I would probably go with Gelid GC-Extreme because it:

  • is nearly the top performer
    • which maximizes the improvement over GD900
  • doesn’t have problem with drying
  • is not very thick
  • is alu-safe

It is expensive though.

All non-liquid-metal thermal pastes are fine on aluminum, never had problems with MX-4 drying out, it’s been in my PC for like 5 years now and temps are the same.

On he other side, I had/have problems with MX-2, after few months it's completely dry? AS-5 was similar, dry after few months.

Why do you need such thermal pastes and extremes? This led gets the maximum output at low currents around 4.5A

I can’t wait to get mine!

Kryonaut is also known for drying up.

That’s exactly my question. :slight_smile:
We can discuss what is better and what is worse. But is the difference going to be 0.1, 1 or 10% with this LED? Anybody bold enough to make a guess or curious enough to try?

Meh, looking at the surface areas of LED board and shelf, this is like 100 times larger than the thermal slug of the LED.
And as long as there’s just a thin layer in between, so preferably with screws or other wise pressed down firmly, it will be fine.
Many tests have shown this.

The drying up seems like the biggest problem though.
Once the grease is dry, it will do a poor job.
So frankly, i think you could maybe better use silicone grease than thermal gunk that will dry up.