1500W LED Flashlight, >100.000 Lumen, >1Mcd

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Holzleim's picture
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Location: Germany
1500W LED Flashlight, >100.000 Lumen, >1Mcd

Want to share this project with some more people being familiar with "slightly bigger" flashlights, so this project is also posted on CPF, for those of you using both platforms.

After some Months of development and build time, it is nearly finished now:

  • around 1.5 kW maximum power
  • >100.000 Lumen total output
  • intensity >1Mcd
  • 3kg weight
  • four groups of light:
    • 1x SBT90.2 behind 62mm TIR optic (tight spot, 560kcd)
    • 4x SBT90.2 behind 30mm TIR optics (medium spot, 500kcd)
    • 8x XHP50.2 in 20mm reflectors (medium width, 160kcd)
    • 8x XHP70.2 without optics (wide flood)
  • 3x buck regulator to drive SBT90.2 at 38A and 4x 33A
  • 4x boost regulator to drive each 4x XHP50/70 at up to 12A
  • 150Wh battery
    • 8x 21700 INR21700-40T
    • 4x 18650 US18650VTC5A
  • 12 lighted buttons for direct access
    • Spot tight more/less
    • Spot wide more/less
    • Mid more/less
    • Flood more/less
    • ALL_ON
    • Tactical Flash Mode
    • Momentary spot tight full, all other off
    • Momentary spot tight and spot wide full, all other off
  • OLED display for extended info/status
  • 2x RGB LED for battery status
  • 36W charging circuitry built in, accepting 5V....12V
  • USB-C or magnetic tabs for charging
  • integrated battery monitoring and balancing circuitry
  • vibration motor for important hints like low-bat warning etc.
  • multiple temperature sensors (and certainly power foldback upon overheating)
  • heatpipes to spread heat from head to body

Will add some beamshots later....


View on the front, protective window still missing (will be delivered mid April)

Here the ALL_ON button was pressed, adjusting all channels to ~75% power

Bringup stage of development process:

Heat of DC/DC converters is conducted through PCB to backside of PCB

many, many threaded holes had to be made....combiantion of alu and copper to keep weight manageble

Short video showing ALL_ON in action:



Size comparison to the light I built before (the samller has 18650 cell, 4x XPL2 for flood and XHP35+20mm TIR spot, 6000Lumen peak, 35kCd; the larger 21700 cell, 4x XHP50.2 flood, XHP35+30mm TIR spot, 12000Lumen peak, 76kCd):

Edited by: Holzleim on 04/10/2021 - 08:56
vestureofblood's picture
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Joined: 08/17/2012 - 15:21
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Location: Missouri

Thats Awesome!!! Thanks for sharing.

In Him (Jesus Christ) was life; and the life was the light of men. And the light shineth in darkness; and the darkness comprehended it not.
http://asflashlights.com/ Everyday Carry Flashlights, plus Upgrades for Maglite.

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I want like 20 of these. I couldn’t afford it, but I want them all the same. That’s pretty amazing.

Marc E
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That just looks immense! Thanks for sharing it here, i’m looking forward to seeing it in action.. once i get my vision back after watching your video Big Smile
Did you build it for a specific purpose or just because you wanted to?

Th558's picture
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SBT90.2 @ 38A? Shocked

Holzleim's picture
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Yes, driving the single spot at 38A, but reducing after some seconds then to ~32A.

I implemented this reducing mechanism for all channels: The very high power is reduced slowly to a level that is safe to operate.

Further, power is reduced if battery voltage drops too low and also with temperature rising.

But due to the 3kg heavy-metal, it can take multiple 100W, or even >1kW rather long.....

And main reason to build it: The building/design itself. Wanted to see what ist possible.

But I certainly also use it: I go out with the dog in the dark (no longer dark now Wink ), and sometimes do some Jogging/Running in the dark.

Firelight2's picture
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Wow! Incredible work. Love

Looks like a new pocket EDC! Silly

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sick LOL

Germans tend to exaggerate engineering sometimes…


Agro's picture
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Very nice. Smile

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Wow, very impressive power and integration of all the electronics!

How do the buttons control all the power converters? There must be some computer/MCU in there?

What made you decide on such a high current, 38A, for the sbt90.2? That is most likely above the max output on the output/current graph.

How are your batteries arranged in terms of series/parallel? What made you choose two different cell types?

djozz's picture
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Wowie! Lots of work -> lots of fun Big Smile Thumbs Up

Holzleim's picture
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Yes, there is a ATxmega128A4U MCU controlling everything (polling buttons, LED converter, charge converter, balancing, display, temp-sensors, ....).

I will do some more measurements (Candela) in the next days, but until now it seemed to be that at least for short time operation brightness reaches max at 38A (~560.000 cd for the center sport; ~520cd coming from the four SBT90.2 behind the 30mm TIRs).

Batteries are arranged 4s3p, resulting in 16.4V full voltage and 4+4+2.6 Ah capacity (measured around 150Wh energy; implemented and automatic battery calibration cycle, so that display now shows items like "runtime left").

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That’s an incredible feat of engineering and design execution. Looking forward to seeing some video in action. How do you manage the cell balancing of the vtc5A vs the 40T? Are they on separate balance circuits?

Holzleim's picture
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There are always two 40T and one VTC5A in parallel, and then these four blocks are in series. So each parallel block is balanced as one cell. I had to choose this battery combination to have enough space available for the electronics. Initially I wanted to use 4x 40T in parallel with 70C LiPo, but due to savety and expected life span I went for save cells only. The pack is now capable of doing around 1.5kW for several seconds, and it does around 1.8kW in Flash Combat Mode. Plenty of runtime with 150Wh....

Photon Master
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Absolutely incredible!! Have you thought of building an even more powerful version with this bad boy?

CBAK Energy Technology, through its BAK Power division, announced that from 2023 it will also produce 25Ah/1kW peak power density 4680 cylindrical cells on a large scale”


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Thanks for taking the time and effort to build your beast! I am super impressed with your advanced knowledge and skills. 

Being able to see your work makes life exciting!

Because I like big lights, my flashlightical views lean heavily toward both the extreme bright and the extreme heft.

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Good job! Thumbs Up

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Bleah, THOR mjolnir

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Welcome to BLF Holzleim. Cool
Very complicated and expensive light you are building Shocked

Holzleim's picture
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@Photon Master: interesting cells, good amount of energy per volume. But already now the battery pack delivers enough power to very quickly heat up both the lamp head (>1 kW being dissipated here on ALL_FULL button), and also the DC/DC converter (LED driver) section. Although efficiency being at ~93%, that still means ~100W peak power being dissipated on the driver PCB.

I checked that my chosen principle of conducting the heat originating from the MOSFET, the power-diode (boost converter) and the Induktors to the backside of the PCB, and then to the aluminium of the lamp body. Put a dense array of vias underneath the components, being filled with tin this conducts pretty good (PCB is only 0.8mm thick). Not suited for automated assembly, but for manual work good.

Originally I hab planned to go for 4x LiPo in parallel with 4x 40T, but for safety and reliability reason I then changed to save cells only. The LiPo initially chosen would have offered endless power: 357A continues, 714A short term current, meaning ~ 5000W continues power 


But I made some bad experience using LiPo, lost a big lamp ~10 years ago due to LiPo cell fault:


@vit55: "Bleah, THOR mjolnir"....what does that mean? Interesting that you mention Mjölnir, that is exactly the name I chose for my device. Will engrave that later into the metal on several locations. I thought of this name because especially the tactical flash-combat mode is very impressive: Use currently around 1800W total power for flashing (2000W  would be possible, can be unleashed later per SW update), not measure yet, but should be >120.000 Lumen during flashes. So the name "Mjölnir" came into my mind....


Will do some beamshots and/or video clip one weather conditions here are better, currently we have continues rain....


@Th558: Thanks for asking this, did some measurements: You were right, the sweet spot for short term (some seconds) seems to be at ~34A; Changes SW now to begin at 34A, then drop down to ~30A over some seconds. I just implemented the 38A hardware-wise, to have enough headroom to max out the sweet spot per SW.

@CNCman: Thanks for the welcome words. Yes, several 100€ accumulated for material, beginning with the SBT90.2 being rather expensive. But that is ok, I will not build such a big one every year....took me already many hours of development and building time...

thefreeman's picture
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Super impressive !

Photon Master
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Wow I want one so bad… (: wish I had your knowledge and could build something like this myself. The heat issue makes perfect sense…

Skylight's picture
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Awesome! Extremely skillful and well executed build. Crown Thumbs Up

I like the way you mounted those XHP70.2 without a PCB.

You should really join the 9th BLF Old Lumens contest this year.

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What a great build Thumbs Up

What I think is that
The SBT in the middle is useful
the four others in the 30mm reflectors are not so a good choice,
cause of many heat.many amps.less throw cause of diameter and so on.
Maybe I am wrong. Innocent

But good skills and well done,thanks for sharing

regards Xandre

Holzleim's picture
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Thanks for the nice words

Maybe some words regarding usefulness:

When I began this project I set me as design targets:

  • I want to build a LED light with > 1000W power, but still being in somewhat "normal" (big)flashlight factor
  • I want to build a useful light, not only aiming at the "wow" factor when using it the first times

Form my previous builds I knew how useful a pure floodlight component is, especially when walking of running in the woods. You can move around the lamp a bit without loosing good sight on the items just in front of you.

My smaller builds had pure flood LEDs without any optics, and then a single spot, being as tight as possible for the chosen lamp size.

Using this combination, I was already very satisfied with flexibility I could achieve.

But I sometime missed something between the tight spot and the pure flood, to light up the path 10-20m in fron of you.

Now, looking at the spot: I made some experiments and fun builds aiming at very tight and intense spots. But although being very impressive and fun to play around with (light sword...), it is not really useful to light up only such a small spot at a far target.

For many of the "light sword" lights you must use binoculars in parallel with the light to make use of it. This becomes even more critical when moving (running or walking), because then the tight light ray bounces a lot and it is even harder to see something in the distance.

With this background I decided that for my big lamp I want the following:

  • Lamp head should not be bigger that ~10x10cm (actually it is 10.4 X 11.4 cm)
  • Array of big LEDs without optics for pure flood -> 8x XP70.2 
  • Something between flood and spot, for 10-20m range -> 8x XHP50.2 in 20mm reflectors
  • Spot in the range 4....8 degree FWHM, fitting in the head, and leaving space for the mid-range elements
    • 1x SBT90.2 in 62mm TIR (LLC56N) giving ~6° FWHM and ~600kCd
    • best space usage made me add 4x SBT90.2 in 30mm TIR (LLC05N7) with ~12° FWHM and additional 500kCd; very nice to light up not only a small spot in the distance, but instead significant area

This setup resulted for me in very good flexibility, offering useful, tight spot, and impressive amount of flood and mid-range lighting.


But at this point, let me put this question here in the community:

Do some of you really have use-cases for the super-long throwers, as they are also being offered these day a commercial products like for example Astrolux MF05 or similar?

I agree, as said above, very fun to play around with, but for real world usage not that often matching an opportunity.

Robin Dobbie
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https://imgbb.com doesn’t put a giant watermark on images.

Completely epic light, btw. A veritable cornucopia of emitters!

Holzleim's picture
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As I just wrote about potential of battery:

This happens when one capacitor accidentally got mechanically damaged, then failing after some days:

Nearly finished repairing this, but the effect would have been significant worse if I had the 700A peak capable LiPo had in the design.....