Flashlight concept #2 - the ideal Luminus SBT-90 Gen. II light

Hello everyone,

We have seen some interesting new flashlights with Luminus SBT-90 Gen. II, e.g. Acebeam's K75 or Nightwatch's NI40. While Acebeam's K75 is too large and too expensive in my humble opinion, the NI40 has a more interesting size but lacks some features like 21700 compatibility, a wider reflector, a nice UI with configurable modes and a good thermal regulation.

With these things in mind I would like to discuss ideas what the ideal SBT-90 Gen. II flashlight should look like and what features would be reasonable to have. Personally, I'm quite thrilled by a size like HaikeLite's MT07 Buffalo but with an up to date battery carrier for higher currents.

My most important questions right now are:

  • What is a reasonable reflector diameter size taken the LEDs die size and lm/W ratio into account?
  • What driver would suit best for this LED? Provided we used a battery tube of 3x 21700 batteries, would a 3s buckdriver (12V) be more useful for a good contstant regulation at less than maximum power or should we better go for FET with 3 cells in parallel and push the SBT90 Gen. II to its very limits?
  • If using FET, how can we deal with the extreme excess heat that is generated with > 20A current?

Desired Hardware Specifications

  • Luminus SBT-90 Gen. II (3V)
  • Titanium/stainless steel bezel
  • 75mm SMO reflector
  • Aluminum Tube (with 3x 21700)
  • E-switch
  • Efficient 3s buckdriver or max.power 3p FET driver
  • Integrated USB-C port (in thread section), maybe with powerbank feature

User Interface

  • Andúril/NarsilM firmware
  • Individually configurable thermal regulation

Interested!

I would like to see one like this and a smaller one like the GT Mini/NI40 combined. I would prefer one cell like the Noctigon K1 but they’ll probably be lights like that soon anyway. Maybe even the K1 will have this LED. I hope so anyway. Would 4 18650s or 3 21700s make more sense? I think we should make the fins as thin as possible so we can increase the number of them but don’t put them too close together unless there’s a fan

You can have both efficient and powerful buck driver. Check this thread from Lexel: Lexels driver compilation. He is developing a 40A CFT-90 buck driver for BLF GT, he has a starting point so.

This would make a very nice thrower, or should i say, cell drainer ?
interested

Maybe the Acebeam K30 GT

I dunno K75’s size is pretty ideal for this emitter. It’s a large emitter and needs a large reflector. It is also a power hungry emitter, and sacking more potential power capacity for a slightly smaller handle wouldn’t make much sense. In small sodacan lights where portability is a concern, 3x18650 tubes make sense, but not for large dedicated throwers. If going with a 3x18650 tube, I would make the reflector much smaller, and just turn it into a combo flood/throw light— “relatively floody.”

The only thing I don’t like about the K75 is that its heat sinking leaves a lot to be desired. While looking good, the random fins halfway up the reflector don’t do much good, and there’s not enough fins down near the neck of the light where they should be. The light gets hot fast— real fast.

I would love the SBT90.2 in something like a maxtoch XPro host, but I don’t think 2 21700s in series would be as ideal as 4 18650s in parallel.

What I think would be a novel concept is something akin to a dedicated handle searchlight like an updated Klarus RS80 with its large 6x18650 battery pack, or even a 6x21700 battery pack, but shape the host in such a way that it’s as compact as possible, and with a singular, large reflector, and then give it a nice handle that is balanced. That way you make it more ergonomic, but while being beefy enough and has enough capacity for turbo.

Very interested in this. I have the Nightwatch and the beam is great.

That's an intruiging idea. How about using the Sofirn SP70 host design (including some upgrades like actual 2x21700 support and SMO reflector)? Certainly, it would need a different driver, too.

Wow, I wasn't aware of the K30 GT yet. However, I think something of size in between K30 GT and K75 could be worth aiming for, couldn't it?

I like the 3*21700 design., but 2*21700 long tube is also interesting

For driver i prefer buck driver more, 3v@20A is 12V@5A, most(if not all) 21700 battery can handle fine, and moreover, we can drain every last juice of battery.

I dont think i will ever need powerbank feature, it’s a nice thing to have, but i think it may rise the cost significant

:sunglasses: Haikelite is doing it.

I hadn’t seen the new acebeam k30gt yet either. My take: though I like the size and 3x cell layout, there are not enough cooling fins, and no 21700 support. It s very similar in head size and length to my catapult v6 which I really like for a jacket pocket light, and the bigger handle of the acebeam should fit the hand better.

.25 lux on an object is not bright enough for me at longer longer distances,since I live and work on a large ranch with both livestock, predators, and big game, so putting lots of lux on an object while far away is paramount…so my acebeam k75 is nice- I use it all the time. It just doesn’t handle the heat well enough, and though it is not that heavy, it is a little bit unwieldy. I’ve often thought that a vertical handle, and more effective cooling fins would make this light better.

Lux, your concept intrigues me. Nobody can seem to get it right with this led. What if you could buy different sized heads to fit on the same handle? Led and driver stay with the handle. Heat transfer would be an issue, but is there a way to make heat transfer to the head better?

My idea:
A configurable body. A lightweight, highly finned head housing a 4 1/2 inch reflector that can either be screwed to a battery handle just like our flashlights, or a separate battery pack on the belt, or a battery pack below a very ergonomic handle similar to modern cordless drills. Hmm, stuff to think about. I can do cad design, and could always 3d print plastic handles and such for prototyping, but dont have machining access anymore.

Doing what?

So, a courui d01 with 21700 in place of 18650 and added features…

3 40T's would be interesting for this LED for sure - great power, decent capacity. Expect 30+ amps draw I suppose?

The MT07 is a beast, though a little big/heavy for me, but a reduced diameter battery holder with 3 21700's would be an advantage.

PearlRiver - what exactly is HL doing?

Looks like a nice light. I’m sure it will do over the stated 260kcd.
I’m talking about something a bit more compact though. IMO it’s a bit heavy for pocket carry. I have an NI40 coming but would prefer a 21700 side switch anduril light which is a bit shorter and lighter.

I'll 2nd that! I find the easier I can carry a light in my pocket, the more use it gets.

I say, the BLF GT4 host with single GT reflector and SBT90.2 :smiley:

The best flashlight is the one that you always have with you. ;-) I fully agree with you except for one thing. I have some doubts that SBT90.2 is an emitter that fits well into a pocket- / EDC- flashlight. I see following challenges here but please feel free to correct me:

Price/Size ratio:

Usually, EDC lights have a quite sensitive pricing level. With a $ 35.00 LED inside the price is likely to reach "premium" areas.

Size/Heat ratio:

SBT90.2 is a monster in terms of excess heat, being driven up to more than 20A. The smaller the flashlight gets, the more difficult it will be to transfer and dissipate the large amounts of heat. Unless driven at lower currents with more efficiency, maybe other LEDs would suit better?

LED/Reflector Size ratio:

With its die size, footprint and domeless layout the SBT90.2 seems to be best for throwers. Since these specs would collide with a small sized reflector, there might be alternative, cheaper but also brandnew LEDs like SST-70 or XM-L3 more appropriate? However, maybe with the right TIR lens the lack of a large diameter-reflector could be compensated somehow.

Lux_perpetua is Haikelite?? Or it look more alike ? Nevermind…

Have anyone try put this sbt90.2 to convoy L2? Does is fit? Just for a try with convoy driver…who know it will be much so low heat? Idk.

I’m just curious how the 20+ amp passing and where the heat will dissipated. I think most about current flow should be regulated constantly with rise with temperature. Or is there any better regulator out there for sbt90.2?