2250 Lumens of Nichia 90CRI Light - Convoy S2+ Shorty Build with GXB172 Boost Driver


Like many people here, I always wanted a small flashlight capable of producing some very high-CRI light, but while also being very bright! ... and yet sensible for everyday use. Sure one could get a basic Convoy S2 light and throw in a Nichia 219B emitter and have a nice light, but the main problem is that.. it's still too dim!

Well I guess that's not very true but it's been pretty difficult to break the ~1500 high-CRI lumen barrier on a single cell, single emitter package, so I thought I'll give the Nichia 144 LEDs a shot!

For those unfamiliar, the Nichia 144 is something like the Cree XHP50 equivalent, using 4 dies together on a same package, and can be driven with either 6V or 12V depending on the configuration. The upsides are generally better tints than Cree, but the downside is that they have a different thermal pad making it incompatible with Cree XHP50 MCPCs.

Clemence recently produced some 16mm MCPCBs specifically for the Nichia 144, so I thought I'd try them out. Big props to Clemence for his work with Nichia LEDs and the very fine MCPCBs he's developed for them! (Check out his thread here: https://budgetlightforum.com/t/-/42898).

I haven't seen any actual small flashlight made around here before with a Nichia 144 LED, so I thought it'll be fun to try it out! Here's the LED reflowed onto the PCB.

Now Djozz managed to do some very fine tests (https://budgetlightforum.com/t/-/42057) with these LEDs. One problem with this LED (here I'm using a E1000 5700K CRI9050 version) is that it's very inefficient! For example, at 6A drive, it only manages about 2500 lumens, while a Cree J4 XHP50 LED (CRI 70 though) does some 4000 lumens (don't worry I'll tackle that soon!). But that's ok! The problem is that we need something like 6A at 6.5V to drive this LED if we want to achieve 2500 lumens!

How to achieve this while still keeping:

  • A single, small lithium cell (no 2S cells, no 26650 cells etc)
  • The same LED (which request a boost driver, but needs to be capable of high power output!)

Fortunately, it was a good way to give my GXB172 driver a first test run!

In fact, I thought this little build would be an ideal first candidate for me to knock out the kinks in the design and firmware for the GXB172 driver which I've recently put together. I won't go into the details here but it's a 17mm full-featured, constant current single-cell Boost driver capable of handling 50W of power! That's more than twice the Kaidomain H1-A boost driver can do. Check this thread for more information (https://budgetlightforum.com/t/-/50015), but keep in mind that too is a work in progress.

So in a way, this build's main goal will be to test out the problems of the GXB172 driver, and to optimize it so hopefully I'll have a decent design I can release so everyone can build their own!

Row-call for the components!

I bought a clear-coated Convoy S2+ host, as well as a shorty-body-tube for this build. Note the 700mAh 18350 WindyFire battery (one of the best hi-drain 18350s around - let me know if there are better ones) which will be used in this light, as well as some Arctic Silver thermal paste, a Nichia 144 E1000 LED which I reflowed onto one of Clemence's 144 MCPCs, my GXB172 driver, and the internal brass pill.

Before assembly, I customized the firmware for this particular light.

I knew I wanted something that was reasonable, which I can also use everyday. So instead for an insane 6A LED drive (which would deplete my small battery in something like 3 to 4 minutes), I decided to go for a more reasonable 4.2A drive which should give me about 2250 lumens. At about 30W of power, this should should be a good test of the GXB172 and provide some decent runtimes and heat management.

The GXB172 was programmed and verified on the bench, and it's ready to be installed!

Above's a general outline of the firmware, just that I configured the Turbo to 4.2A, Bright to 800 lumens, Med to 200 lumens, and enabled memory and candlelight mode just for fun!

Again I won't go into the discussion on the firmware, and yes it will work with Bistro / Narsil etc with modifications and porting changes, but check my GXB172 thread for more discussion on that.

In order to maximize performance, a phosphor bronze spring was used with a spring bypass for good measure. I also soldered the spring on upside down - yes verified that it fits my flat-top batteries just fine! We'll need all the current we can get from our battery (expected ~8 to 9A or so!). This spring was specifically chosen so it would fit on the small spring pad on the GXB172, and yet have as large a contact area as possible to the battery terminal.

Everything fits together pretty well!

The stock Convoy S2+ comes with a clear reflector, so I swapped it out with an orange-peel one! The Nichia 144 is one pretty LED! Care was taken to insulate the wires and reflector to make sure nothing was shorting the output, which would be a bad thing!

Finally it all comes together!


Above is a very quick video showing the basic functionality of the flashlight, and to show you that I'm not making this up! The light is extremely bright! But my camera stops down pretty quickly so I'll make another one properly when I have the time in the future.

After putting it together, everything worked great the first time around! There are some additional fun things I haven't covered yet , but feel free to check this page and I'll be updating it with more information soon!

Next up, more detailed and everyday use testing and tweaks to come. I'm sure there are a lot of tiny little problems and bugs to be found and ironed out, so I'll be working on them! This is only the beginning of the project!

Thanks for reading ^_^


nice one!


Nice job. :+1:
A good single cell boost driver has been needed for a long time.

I’ve got several 144’s just waiting for this! Good job

Man this is exciting news

I’ve been waiting for this for a long time :slight_smile:

Nice build! Inspiration….

Excellent .

Looks good!

Maybe you can use a Nanjg style spring it may fit better?

Would you know the total current draw from the battery? Is it around 7amps?

Since you asked, the Aspire 18350 cell is quite a bit better, especially for this high drain application. Not too sure where to buy them though. They have been slowly disappearing at all online stores.

See HKJ’s tests for these two at 5A and 10A:

Maybe Vapcell 18350 1100mah from liionwholesale as a runner up?

The Efest IMR18350 700mAh are also a bit better than the Windyfire (at least at higher Amps), despite not better than the Aspire 110mAh/ Keeppower 1200mAh (and eventually the Vapcell) :wink:

EDIT: Sorry: nice work with this :wink: I will take a look on your other thread, to see if this driver suits my “needs” for a blast of light :smiling_imp:

The Vapcell 18350 1100mAh is supposed to be the same cell as the Asprire 18350 cell.

Nice build with a great driver!

Thanks everyone very much for the kind comments!

Yes the Nanjg spring looks more appropriate to the driver, but as you can guess, the total current draw from the battery is pretty high even with my output turned down to 4.2A. Current draw depends on the battery (how much the voltage drops as current is being drawn), as well as contact resistances etc. I measured just about 8A or so on the bench but it might be a little different inside the flashlight itself due to contact resistances etc. These play a big deal since even just 50mR of extra resistance somewhere = 0.4V drop at 8A - very significant. As a result, I decided to go for as big a contact I can with the spring, so I chose this bronze spring which has a large contact patch to the battery-end.

Thanks everyone for the good suggestions for 18350 cells. I'll pick some of them up and they should provide better performance than the WindyFire!

Awesome job!

Where’s the group-buy for those drivers? :heart_eyes:

No 'group buy' just yet, but if the response is good I think we can look into getting a batch of them assembled and made ^_^. Check out the GXB172 thread for more information on the driver: https://budgetlightforum.com/t/-/50015. Thanks for your comments!

Made by the same factory in China. Yongdeli

Looks great! The candle mode is really cool!

Thanks! It's a really simple flicker algorithm but I have some ideas to make it more realistic. I suppose the first step is to try it out in a <3000K flashlight though because it looks a little odd now coming from a 5700K emitter. I tested it yesterday night with a yellow plastic bottle on top of it in a dark room, and it was surprisingly pleasant, would be fun in outdoor camping I think. I'm also pretty sure I've seen some mention of candle flicker and other modes in some custom firmwares, like in the BLF lantern, or some of the modes in Toykeeper's firmwares.

Many thanks for sharing this excellent build! In line with true BLF spirit, this is a good inspiration. really cool build.
I like the candle flicker mode, was wondering why almost no other light has it.

Awesome job man! Congrats!