3S 26650 12x 219b Mag build - help finding a driver

Flashlight Modding and DIY Parts
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I have been deep diving over the past week bringing myself back up to speed on flashlight modding, and am stumped on what driver I should use for my build. I know I need a 12v to 3v buck circuit, and that my build must be very commonly done during the Mag mod craze, but I can’t find what I think I need available anywhere. And I definitely don’t want to pop my rare 219b leds.

My theme for this build is 3D mag vibe but way brighter. Long running, doesn’t overheat in 15 minutes, wall of light. Basically what the 3D mag was to me as a kid, when 60 lumens was hugely bright, and 500 lumens was the sun. I want at least a thousand lumens out of this in high cri where I don’t have to worry about babying the light.

Host:
3D incan Maglight

MCPCB:
I’d really like to find a 50mm mcpcb that spreads the leds further apart, but can’t find anything like that without contacting custom pcb makers. So I’m choosing the following because it seems well made and will let me use the MCPCB style for smaller builds in the future if I want. And it’s available in the USA.

SL 12x 3535 Copper MCPCB
https://www.mtnelectronics.com/index.php?route=product/product&product_id=1005

LEDs:
12x Nichia 219b 2700k

I love this particular LED and have them on hand and think it would be perfect for this build. If you think there is a single led that would work better for it overall, let me know.

Batteries:
3x Vapcell 26650 7000mah 30A K70 Rechargeable INR Button Top Battery

In series with magnets between the cells to allow continuity. I suppose I’ll have to machine a bit from the inside of the tail and fit a lower profile spring. Plus a sleeve in the tube to keep the width proper.

Heatsink:

I have some aluminum, brass, and delrin on order I’ll machine down to fit inside the head of the light and adapt to the contacts for the bulb, that I’ll make room for the MCPCB in, and put thermal paste around the outside to help contact to to the head of the light. I know I could just get a p60 adapter from malkoff, but I figure it will be more fun to try and make my own since I have a lathe and mill.

Driver:
Here is where I’m stumped. I know I need a buck for the 12v from the cells down to the 3v the 219b needs. I figure each led needs 2.5A to not be over driven and hot and still provide good output. But 12x in parallel has a higher amp need, right? So 30A out of the buck driver? Or, if not, then 2.5A out of the buck driver. Both of which aren’t options on MTN electronics who sells the mega mule components my MCPCB is part of.

Am I way off on my assumption? And if the LED board really does need 30A, I should be good with the 30A rated 26650, right?

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12 3V LEDs at 2.5A each that close to each other without a proper heatsink? I wouldn’t even think of that.

You write you want at least 1000 Lumens, so I figured you will severly underdrive each LED with like 350mA or something to get to 1500lm or whatever, but 2.5A per LED makes ~1000?ish Lumen per LED, so 12k Lumen for all 12.
You can drive that with enough thermal mass, sure, but I wouldn’t want to drive those LEDs without a driver with thermal protection.

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Had the same problem - finding a high amp driver with 12v input for 3v LEDs is problematic. Easiest solution is to use 1x 6v LED and this driver from Kaidomain:

One can use it witn 1x6v LED, or 2x3v LEDs in series - Convoy sells LHP73B on 16mm, they will fit inside Mag 3D (You can even fit 3x16mm PCB inside 3D with a little bit of sanding them down in certain areas). 2xLHP73B with this driver should get You about 6000 lumens. Downside - 70CRI. But tint is quite pleasant…

Edit:
I read OPs post one more time - You plan to use other radiator, than I plan in my Mag project - since You have 50mm radiator diameter You should be able to fit (that needs to be verified) 4x 16mm PCBs. 4xLHP73B will get You 7500 lumens with driver listed above. Stock Mag switch should be fine with 5A of current.

Edit 2:
If You choose to go with Mag 2D instead of 3D, You can get this driver from Convoy along with LEDs.
30mm 6V 8A driver for L6 XHP70.3 - Convoy flashlight.
And also there are 6v LEDs with high CRI - SFT70 3000K, You can use 4x in parallel. With 8A driver You should get +/- 3800 lumens.
And kaidomain has AR coated glass for Maglites.

1 Thank
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This is a great suggestion and gives OP a lot more flexibility.

If OP can find a 12V to 3V driver, then 4xSFT40 3000K in parallel is a great combo.

If OP can find 12V to 6V driver, then 4xSFT70 3000K in parallel.

If OP can find 12V to 12V, then 4xSFT40 in series or 4xSFT70 in 2S2P would both work.

These emitters are much more efficient and robust than the 219B, while giving better quality of light. They also let you choose 4 TIRs, one for each emitter, to customize the beam profile as you like it.

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Since when does a SFT40 deliver better light than 219b?

If there is a 12v to 6v driver, a 2S2P with 3V LEDs is also possible
Or just use 3 3v LEDs in series, maybe even 7070? LHP73b should come out in high CRI at some point

For 6V LEDs, keep the B35AM in mind.
For 12V LED - FC40?

Do you want substantial throw or is flood alright? What about a mule?

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WB, hiyaside!

27 Jennifer Garner
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It’s hard to find color reports of the 219B 3000K, but here’s one indicating +1.1mDuv, 95.2 CRI, 84.5 R9, compared to the consistent 97-98 CRI achieved by SFT40. There are also different bins of 219B floating around, and if you’re unlucky you can end up with one that’s a decent bit greener than 519A as in this comparison. On the other hand, all 4 of my HB4 binned SFT40/70’s are a bit rosier than a halogen bulb.

Nichia’s LEDs tend to struggle with blue spike and cyan dip, while Luminus’s 95CRI 3000K does a great job addressing this. This is particularly evident when comparing the 519A against SFT40:

Screenshot 2025-04-21 151438
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Screenshot 2025-04-21 151611
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Of course, OP can choose to use the 219B if they so desire–the 2700K has a good chance of faring better. I personally find SFT40/70 a better engineering solution that also provides more flexibility in drivers/optics. A single SFT40 has the output of 2x219B in parallel; for the SFT70 it’s closer to 4x219B, and has no difficulty pumping out 1000+lm even with a single emitter. And as @L4M4 remarked earlier, 12 LEDs is overkill for 1000 lumens.

If OP is willing to wait, this is a good solution if OP wants to maximize the output/efficiency and minimize the cost as much as possible.

For any CCT other than 3000K, B35AM is a fantastic emitter if one doesn’t need throw and drives them conservatively. For 3000K, the SFT70 is strictly superior in every way: standard footprint, compatible with standard optics/gaskets, more output, better thermals, better power handling, higher intensity…

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This estimate is a bit optimistic, as even the 4500K variant barely puts out 550lm at 2.5A. But I do agree that 12x of them is unnecessary–more LEDs at a lower current is always more efficient, but the extra efficiency diminishes extremely fast with the number of LEDs. Eventually the extra efficiency is outweighed by extra optical losses.