【convoy】L21B SFT40 3000K Ra=95 available now

I have one installed in a Z1 with the 6A driver, I got approx 950m. Unfortunately I didn’t write the candela down

Thanks, that’s good to know. Looks like Simon’s listing is with a 6A driver too. 950m definitely beats my current furthest thrower (FT03 XHP50.2 @ 735m).

I hope your Z1 doesn’t squeak like all 20pcs of mine. Careful dismantling to add lubricant that you don’t slice the orings. There is one at the rear of the head, make sure it’s in place and screw the head back on very slowly. Quite a few on BLF have sliced it

Yeah, I saw reports of that after I ordered. I’ll report back if I get a squeeky one. Thanks for the tips.

Just tested mine on a fresh charged 40T.
My Lux readings are always on the high side so probably reading at least 10% too high.
I have measured it at 5 m for 19600 Lx which equals 490 kCd (Approx. 1400m)

Taking into account a 10% error still makes it 440 kCd (Approx. 1326 m)

Lumens are measured with my Lumen tube calibrated against a Maukka calibration light, measured 1490 Lm at startup.

The hotspot of the 2mm is almost double the size of the 1mm2, which makes it a great thrower which has far better usability than the 1mm (that is a great laser like beam, but its got a very tiny hotspot.)

My L21A with WF 1mm2 and 5A driver measures 840 Lm and 22500 Lx which equals 562,5 kCd

Thanks mate… Now on my notes, there are 3 sets of data measured at 1300m ish…

Thanks mate… Now on my notes, there are 3 sets of data measured at 1300m ish…


There’ll never be the same measurement across the board when the led is driven above its rated spec

What is the reading at 30s?

The flashlight hosts are almost completed.
Next, the manufacturer will start to produce 18A drivers. Considering the matching problem, some adjustments may be needed.

I’ve just measured that for you, it drops 110 Lm after that it’s pretty stable and doesnt drop very hard anymore

That’s higher than what I was able to achieve on 3 of mine.

I got different readings for other set ups too. These are all different chips of the CULPM1

7A - 1313 & 8A - 1318 (same chip)
7A - 1260
6A - 1300
6A - 1200

Just shows how much variation these Osram chips have.

On the datasheet for the 8RF bin, Simon sells, has got a Min 1690 lm and Max 1900 lm at 6A

Matching problem? BTW, I’m very excited about this light!

Just dropped in (last couple of pages). 3 x 21700 light picks my curiosity.

Any rendering or some info?

Likely very similar style to the 4x18a. Though I personally wouldn’t mind a little extra aluminum be left behind in the head at the bottom of the reflector well with deeper fins and a thinner bezel that allows for a larger reflector.


please could anyone explain, how does low-voltage protection/warning on S2+ 5000mAh / S21A 6000mAh drivers work?
Is it warning only - starts flashing once voltage decreases to certain level? Or does it also cut off the battery - if so, at what voltage?

Also, how does the driver work? What is the max. current on let’s say 50% load? Does it pull 2500mA continuously? Or “caches” 5000mA then 0 for a while, and so on?

I’ve pulled some ICR18650-26Ds from dead laptop battery (2 out of 9 cells dead), and would like to know, whether I can use them. They are rated at 5200mA max current, but I don’t want to push luck drawing 5A off them. At the same time - they’re not protected, thus my interest in voltage cutoff.

Someone else can chime in on your questions but I wouldn’t use the ICR chemisty, specially old cells. ICR can be dangerous without an added protection circuit.

You’d ideally want to use cells with a current rating of 10A+ for a 5-6A driver current. These flashlights require the highest possible voltage on load, when drawing a high load the voltage will drop and how far that drop is depends on the performance of the cell used. There are other factors but I’ll leave it at that. For a 5A cell I’d advise 3A max load. Get something decent. Note that old used cells have a higher risk depending on how healthy it is. If a cell gets unstable just remember you’re holding a sealed metal tube that has the potential to explode

Just a warning S21B does not go along with 20->22mm adapter from KD. The adapter is too high and you cannot screw the retaining ring. It accepts only genuine 22mm drivers. Until you find lower adapter or you file it down.


First of all can't say how the driver cut-off works (never experienced it yet), but the word says cut-off, which is self-explaining.

Cut-off in drivers is one of those things which overall needs room for improvement. In my opinion it is overall set too high (read my P.S. in #3881 post here).

There's still too much actual ignorance about li-ion cells, and besides positive beliefs in this matter I have some straightforward experience. Like leaving a couple scavenged ICR18650-26C cells straight connected to a white led with thin wires for many days (with no driver - closest config to a direct drive setup, less resistance and faster result). Consider the minimum Vf of a white led is around 2.5V or close. This means a li-ion battery connected to a simple direct drive, linear or buck driver driving a white led just cannot get overdischarged. Back to my experience, after disconnection the cells climbed well above 2.5V, which is to be expected.

Another thing I can narrate is my latest experience with my li-ion converted hair clipper. Powered by two TurdFire IMR14500 700mAh (LoL!) cells in parallel, weeks ago I noticed them going weak and losing charge quickly (very high self-discharge). Since I needed it, while I ordered and waited for new cells I recharged the appliance every few days. At some point I forgot to recharge it for many days, and when I noticed it wouldn't even turn on or barely move without load. And still, I confidently dared to recharge it. Nothing wrong happened (it still works right and today or tomorrow will give the old cells their last run). Why? Because li-ion batteries need time to chemically decompose at low voltages. Can't say how much, but must be quite lenghty. I know what I'm saying because I also dared to recharge a couple of the above mentioned ICR18650-26C cells from 1.7V or around. It was a pack of 6 from an old laptop battery and I recharged and tested them all without problems. At last I raised all cells to ≈3.9V and observed their self-discharge over a few weeks. Two cells lost some voltage, and so I discarded them. I kept the rest.

But well, you are free to believe as you like - and deal with the results or consequences.

P.S.: On a side note, overall low lifespan for these (now old) cells. Sold better binned and improved also under other wraps: Shockli and Vapcell, for example. Heter is their OEM manufacturer.

Mon, 11/23/2020 - 13:58


Had 4pcs 30Q discharge to 0v and left like that for 4 days, no hope whatsoever in reviving that low.

That’s quite possibly correct what Barkuti says but it’s a different story if a light has parasitic drain in an e-switch. That’s different altogether though, only a protected cell will stop that issue