Introduction: How to Build an Insanely Bright LED Flashlight!

Picture of How to Build an Insanely Bright LED Flashlight!

In this Instructable (my first) I am going to show you how I built this ridiculously bright handheld LED flashlight so that you too can turn night into day... and impress your friends.

Most of us use flashlights quite often for activities like camping, walking at night, or simply just going outside in the dark. However, the majority of us settle for those cheap value packs from the checkout at the local hardware store. These cheap flashlights produce a useless amount of light if any at all. To resolve this issue I designed and built this crazy bright, surprisingly useful, and very impressive flashlight that is great for lighting your way in the dark, creating cool video and photography effects like sci-fi glowing orbs, using as a work light, and many other things, all for a reasonable cost.

Step 1: Materials and Cost

Picture of Materials and Cost

Here is a list of the parts I used, however, anything similar should work as well. Amazon links are included (I live in Canada so prices and links are mostly Canadian, this should also benefit people who live in the U.S. because of the dollar ).

boost converter - CDN$ 18.01 -

XT60 connectors - CDN$ 2.99 -

LiPo Battery alarm - CDN$ 3.99 -

Switches - CDN$ 6.17 -

Volt/Ammeter - CDN$ 13.57 -

Heatsink - CDN$ 20.04 -

100w LED - USD$ 10.49 -

Lens and reflector - USD$ 4.99 -

11.1v LiPo Batteries (chose whichever apply best to your uses)

CDN$ 24.88 -

CDN$ 49.00 - (This is a 2 pack of the newer version of above battery)

CDN$ 85.14 - (higher capacity for higher budgets)

CDN$ 53.00 - (also larger capacity)

Battery charger - CDN$ 27.59 - (does not include power supply)

Balance Charger Cable Extension - CDN$ 2.04 -

You will also need various materials like wire, terminal blocks, fuses/fuse holder, solder, heat shrink, etc.

The total cost should be under $200, however, it will be comparable with products that cost $600+ Keep in mind, the batteries and charger can be used for other things too, they are not dedicated to this project. Also, this price includes the learning experiences and knowledge that you will gain in doing a project like this one.That is priceless.

Step 2: Design/ How It Works

Picture of Design/ How It Works

So, because the LED in this "weapon of mass illumination" draws a lot of power, up to 100 watts (33 volts and 3 amps), it produces an insane amount of heat, so we need a heatsink to keep it cool, the one that I listed in the parts list may seem like overkill, and it is a little overkill (only a little), but so is this whole build.

To provide enough power to feed this hungry beast, we will need a powerful battery that is designed for high discharge applications and compact and lightweight, this is a portable flashlight after all (rules out lead acid). The obvious solution to both of these requirements is a Lithium Polymer battery (Li-Po). Li-Po batteries are commonly used to power high-performance drones, RC cars, and electric cars. They are small, lightweight, and can discharge very quickly, perfect for our flashlight. I went with an 11.1v Li-Po battery (linked in the materials section).

But wait... the LED needs 33 volts and the battery is only 11.1 volts?! This is where the boost converter comes in. The converter "boosts"the 11.1v from the battery to the 33v required by the LED, or whatever you set it to using the on-board potentiometer to adjust the output voltage. We will have to be careful though because the LED should never get more than 34v, and it will only light up at a minimum of about 26v, therefore we need some way to monitor the output voltage of the boost converter, which leads us to the next component... The digital meter allows us to do just that, and with it, we can see the voltage and current going to the LED. This makes it very easy to adjust the brightness of the light, and also to prevent overpowering the LED. For additional protection, we have a 4 amp fuse on the output of the boost converter because no matter how fun it would be to try and blow up a 100w LED I didn't want to wait for shipping again.

Next up we have the battery alarm. The purpose of the alarm is to protect the battery from over discharging which is necessary due to the sensitive chemistry in Li-Po batteries. Each cell will fully charge up to 4.2 volts per cell and cannot drop below 3 volts per cell at an absolute minimum. If the voltage falls below 3 volts then it will rapidly drop to 1 or 2 volts and damage the cell. However, we avoid this by setting the battery alarm beep at 3.2 volts (using the button on the top), but if for some mysterious unknown reason the voltage does happen to drop too low, don't panic, just throw the battery on your balance charger and charge it at a low charge rate and you can often recover the cell with minimal damage.

In this design, I decided to use 2 switches, one master power switch and one switch just for the LED. I did this so that I could have the fan, battery alarm, and the digital meter on without the LED being on. With this design I am able to see the battery voltage with or without a load, also, it sounds cool when I switch on the master power and it beeps and whirs as everything powers up.

Step 3: Mount LED to Heatsink

Picture of Mount LED to Heatsink

In order to mount the LED to the heat sink first apply the thermal paste, do this as shown above (or whatever method you prefer, I know that thermal paste application can be a very... controversial subject?). I then had to use a small scrap piece of an aluminum heat sink which I then bolted to the LED, clamping it onto the heat sink, as shown in the pictures above. Be careful not to tighten the bolts too much or you will bend the LED.

You can also add the lens and reflector here using epoxy to attach it to the LED.

Step 4: Case

Picture of Case

For the case, I up-cycled an old flashlight that was broken and being thrown away. I started by gutting the internals which consisted of a car headlight and 2 small lead acid batteries. I recycled the batteries and got to work modifying the case to fit my components. You will only need the essentials for this step: hot glue, epoxy, sandpaper, and a Dremel.

I started by removing some supports with my trusty Dremel (Dremels are awesome tools). Next, I assembled most of the parts, leaving the wires extra long to cut to length later, and attached them to the reflector. Epoxy is your best friend when doing anything like this. I test fit the assembly into the case, it fit perfectly. I then cut vents for the fan and finished them with pieces of speaker grill I recycled from a broken Ipod dock. At this point I cut and sanded the slots for the: digital meter, battery alarm, master switch, and the trimmer potentiometer mounting them, along with the boost converter, using plenty of hot glue, because nobody will see the inside, right?

I added some finishing touches like Velcro on the batteries and the roof of the case for easy mounting, as well as some decals that came with my batteries. And it was time to wire.

I know many of you will not have the luxury of using an existing case so I am excited to see what ideas you all come up with for your case. Be creative and make it you own.

Step 5: Wiring

Picture of Wiring

I have included a simple schematic that shows how to wire all the components.

When wiring, be sure to leave the wires long enough to fit in your case. I did the majority of my wiring before putting everything into my case, however, you may choose to wire after, depending on your case.

For this Step, you will need a terminal block for the ground and power connections, wire (12 or 14 AWG for high power connections), a 4 amp fuse and fuse holder, and various other small materials.

*don't forget to use heat shrink tubing for all possible connections*

First solder some wire onto a female XT60 connector and put a switch in series with the ground wire, this will serve as the master power switch. Next, fasten the ends into the terminal block creating positive and ground rails (depending on the type of terminal block you use you may have to bridge wire to other terminals for each connection).

Boost converter

Solder the inputs to power and ground

Add a switch and a fuse holder to the negative output. We will use a 4 amp fuse here.

Also, you will want to have an accessible potentiometer for adjusting the voltage going to the LED. I just extended the trimmer POT that was already on the converter.

digital meter and LED

Connect the 2 thin wires to power in the terminal block, red to positive, and black to ground.

The thicker black wire goes to the negative output of the boost converter, after the fuse holder.

The yellow wire goes to the negative terminal of the LED

The thicker red wire goes to the positive output of the boost converter.

Battery alarm

To wire the alarm, connect the balance connector extension to pins ground to 3, however, snip the ground wire and connect it to the main ground on the terminal block.

Step 6: What Not to Do

Picture of What Not to Do

Here is a list of what NOT to do:

My mistakes mostly involved the boost converter, and I actually blew up 4 boards in the prototyping process of this build. But it's OK because that's how you learn, at least that's the best excuse I could come up with.

Converter 1 & 2 (yes i did it twice :( . Don't short the output - the board will pop and sizzle. The first time I did this I was touching the wires to the LED for the first time. As I turned up the voltage the LED blinded me and I accidentally shorted the wires.

Converter 3. Don't rush and try to pull off the wires before the solder is fully melted, you will pull off the solder pad. The solder is lead-free so it will take a lot more heat to melt than good old 60/40.

Converter 4. Don't accidentally reverse the input polarity, there WILL be fireworks with this one.

Aside from that everything went fairly smooth.

Step 7: Changes/version 2

Soon I plan to:

- upgrade the trimmer potentiometer with a proper one that has a nice knob, and add voltage limit somehow.

- make an adapter to plug in 2 batteries in parallel.

- make a fan controller

- experiment with making the beam narrower

- make an adapter to plug into a mains powered supply like a Laptop supply

Also, I am going to make a second version of this light in which I plan to make smaller and waterproof by making the case itself the heatsink. I will upload another instructable on that when it is complete.

Step 8: Gallery

Picture of Gallery

Thanks for reading my first Instructable. If you have any questions, concerns, or suggestions please post them in the comments and I will do my best to answer them. Also, for those of you who build this light please post pictures as well. I can't wait to see what you have come up with in your design!


mcduffiechris (author)2017-04-04

Neat project; however, that is nowhere near being a "cheap" project. I understand the neatness of building something like this, but if you just wanted to buy an equally bright flashlight (9,000 lumens), you could simply buy the $20 chinese ones online, and you get two with chargers for the batteries. But, back to being positive, it was evident you put a lot of time into it. Kudos to you.

HillTech (author)mcduffiechris2017-04-04

Thanks for the comment,

Of course, you could buy those ones but they are only claimed to be 9000 lumens and most of them are nowhere close .

clark5113 (author)HillTech2018-01-04

And nothing like that lasts long IMO. What you have is the difference between a Zippo lighter and a Bic. How long can you use it before it discharges? I reread and still couldn't find this info.

maxstedt (author)2017-03-03


You blokes do a great job.

marktm200 (author)2017-02-13

Anyone have an idea of how to build an infrared (~880 nm) high intensity system? I have a large 48 volt DC power supply - just need the actual light!

marktm200 (author)marktm2002017-03-03

First attempt at the 880 nm illumination system was fairly successful. Simply mounted 4 (cheap ~ $7) outdoor 12 vdc IR illuminators on a rack that attached to the golf cart's window frame - then hooked them all in series to my 48 VDC battery system. Very bright up to 100+ feet, but not focused enough. Going to work on a focus system. If interested in more details, let me know.

HillTech (author)marktm2002017-03-03

I would love to see some pictures

marktm200 made it! (author)HillTech2017-03-03

The illuminators are mounted on an extra rail clamp from a broken windshield that I replaced recently. The 48 VDC wiring is from my sprayer assembly that has a toggle switch. The illuminators are all in series and are all different types - so likely some are over-voltaged and others under, but all come on - believe they are all similar. The old Sony night shot camera picks up the IR (840 nm) very well and over 100 feet with a very broad view (the IR lighting on the Camera is covered - basically meaningless). So easy, but seems to really work. An improvement would be to use all illuminators of the 4 element type - they have a more focused lens on them and seem to be brighter than the 48 element type - however a little more expensive.

I'd like to build a night vision 3D "google" using similar technology that Mattgyver92 has built with the highest resolution possible - but just starting to learn about that area. This would "compliment" my night vision golf cart - with plenty of portable power.

HillTech (author)marktm2002017-03-03

This is cool, what is the reason for using IR light

marktm200 (author)HillTech2017-03-03

If I can find/design/build a 3D IR night vision goggle system, I'll use the IR lighting system to see at night as I drive/park the golf cart around my property - in a stealth mode. My ultimate goal is to able to "see" the open sites in my rifle to shoot feral hogs - don't really know if it's possible, but I'm going to give it a try.

JohnC430 (author)marktm2002017-02-14

infrared is not visible light. what will you do with it? there are infrared LED's but they are not "high brightness" because most of the high brightness are made in either red or green or white. if u can get the high brightness infrared LED's then just use them like this guy has made his white LED's.

MarkI36 (author)2017-02-09

This flashlight has the same 9000 lumens and comes complete for $160 to $200.

Lorax98 (author)MarkI362017-02-09

Boy, us Canadians wish we could get those prices. Here is the same
$200 USD flashlight on for over $800. Canadian retailers are

DodgeD (author)Lorax982017-02-28

Yes we can thank the Canadian government for a lot of this by way of high tariffs on goods and of course the long favorite pass time " Canadians ripping off Canadians" end quote.

meritsetgo (author)Lorax982017-02-10

wow same kit on amazon $276

BG17 (author)MarkI362017-02-10

These flashlights may well be able to produce the 9000 lumens but not for long. They have no active cooling so very rapidly lower the power to keep the temperature down. "sensor in real time, and prevents overheating by reducing the output". My Nitecore TM06 has the same type of thermal management, it can output 4000 lumens but only for about 25 seconds.

So in reality these units are a gimmick and very expensive.

The OP's heatsink could cool a power station!

savagemom2 (author)2017-02-19

I love the insanely bright LED flashlight!!! But it's way beyond my skill level and with the inaccurate schematics I don't dare ask my husband or son to help me with it. So I guess I'll just stay inside when it's dark.

HillTech (author)savagemom22017-02-20

hi, if you do want to build the light I can help to answer any questions you may have. Also, the schematic was meant just to give a visual representation of the basic wiring layout, refer the the written instructions for more detailed instructions.

JohnC430 (author)2017-02-14

oh yeah, I just read what he wrote about "dont short the output of the boost converter" another thing my modification will allow you to do is to short the output without blowing up the converter.... LOL.

JohnC430 (author)2017-02-14

Wow! Canadian prices are crazy! I bought a few of that same Boost converter for $3 each. bought a few to make a 8Amp battery chargers by modifying the boost inductor to make it into a regular "Flyback". it meant I had to change stuff... add one more wire to the winding and add some snubbers because I used extra diodes etc. the control circuitry is the same.

kbouchard1 (author)2017-02-10

If you want to go for it here for $500 is the most powerful light I can find on Amazon. 12000 lumens.

My question becomes, how legal these are to own, in that it could blind someone if abused. Also assume these would be illegal to use in any traffic as it might actually cause an accident when you shine it at a car.

JohnC430 (author)kbouchard12017-02-14

I actually checked for the legal maximum brightness of car headlights. neither in Canada nor in California are there any limits. looks like 55 Watts is the biggest manufactured lights on the road but I am sure there are those who make their own and use them. especially when off-roading, marine or RV types.

1Vega (author)kbouchard12017-02-11

you should contact you local pd since all areas have different rules... even if there are o law probably should not be flashing people with it

JP_AustinTx (author)2017-02-12

Is the schematic accurate? Looks odd how the + from the boost reg is going into the LED on the cathode. I would have though the LED is turned around so you could measure the voltage across the LED module. After looking at it for a while I think there are several questionable symbols and labels in the schematic.

JohnC430 (author)JP_AustinTx2017-02-14

yeah the schematic is a mess but if u can spot the errors then u should also be able to fix them for yourself. no biggie !!!

HillTech (author)JP_AustinTx2017-02-12

I apologise for the issues in the schematic, you are correct that the LED should be flipped. Also this schematic is very basic and just ment to show the wording layout.

kbouchard1 (author)2017-02-10

It would be cool to loop this project into one to use underwater for diving purposes, where that would be a more practical use. Perhaps someone will do that, as I can see these would serve well with diving and even just swimming.

stephen corriveau (author)2017-02-10


DavidM638 (author)2017-02-10

I like playing with circuits like this, but I use a chopper circuit to pulse the LED and save power. You give up some brightness for longer discharge time.

TJLee089 (author)2017-02-09

Battery is 2.2Ah, 11.1v, therefore, 24.42 wh.

Light draws 100w, therefore, (24.42/100)x60=14.6 minutes to full discharge

About right?

HillTech (author)TJLee0892017-02-10

I have just done some runtime test to answer your question.
running the light like I normally do, adjusted so the led is drawing 2 amps, it ran for 26 minutes on the 2200mAh battery.
running at full power (3 amps) it ran for 17 minutes on the same battery.

ClaudioP34 (author)2017-02-10

"experiment with making the beam narrower"

To make the beam narrower, you shall not use the reflector from the lamp.

The lens you put on the LED already focuses the beam. Usually the lenses can be chosen to have a beam 120° wide, or 90° wide, or less. So, first step, just change the LED lens with one with a narrower beam angle.

Second, the reflector of the old lamp was intended to be used with an old-stile car headlight which spread the light all over around the light bulb (while the LED send the beam almost from a flat surface): that's why the LED car headlights sold to replace old lights are arranged with many LEDs around "fake light bulbs" structures. Reflectors are intended to be more-or-less parabolic, with the bulb about in the focus. So, the reflector you are using is doing almost nothing to control the beam.

Good news, it is easy and cheap enough to draw a parabola with the needed geometry, and DIY a cheap parabolic reflector. Use Google for ideas, it's plenty of projects that can be modified for your necessity (avoid the ones that are not explaining the geometry involved. Usually are used for solar ovens).

Also, I saw some cheap, plastic, Fresnel lenses sold at "maker fairs" for doing science experiment that can be used to focus the beam of the LED. You can look on E-Bay for the cheaper ones. Just place the LED in the focal spot of the lens (you can measure the actual focal length just by focusing the Sun light on the focal spot). You shall match the right LED diffuser lense with the right beam angle to illuminate the Fresnel lens without wasting light.

Just keep experimenting.

Let me know if you go with the Fresnel lens or a DIY parabolic reflector, and the results.

auto13142828 (author)2017-02-09

Nice but way too expensive!

terryd15 (author)auto131428282017-02-09

I got the price down to less than 75 CN dollars after about 15 minutes research on eBay, including a balance charger and mid range LiPo battery specified (but I already have those last two and an old heatsink which takes 35 CN dollars off the cost so components cost around 40 CN dollars or about 30 US dollars). I don't call that too expensive

terryd15 (author)auto131428282017-02-09

not if you get the bits from China via eBay rather than Amazon - much cheaper - and most of us have the odd LiPo and charger around to use with drones and other stuff.

ccpanel (author)2017-02-09

18V ryobi dual fuel LED work light

1700 lumens


does battery and 110 cord.

sWillyPs (author)ccpanel2017-02-09

I have one of those Ryobi lights, great light, I use it everyday on the jobsite. But, this Instructable isn't about going to Home Depot and buying a light (don't forget the battery and charger) it's about building your own light.

ccpanel (author)sWillyPs2017-02-09

That is an awesome concept.




time for me to enjoy futzin around learning new things=0

HillTech (author)ccpanel2017-02-09

great example. so for only 3 times the price you are getting over 5 times the light output, and the learning experience, and the sentimental value of building it yourself.

mach1950 (author)2017-02-09

Great instructable, great idea, great experiment. Ignore every negative comment, buying an alternate torch is so far out of the atmosphere it may as well be in another galaxy. People who don't understand this site need to learn why we are here or leave.

HillTech (author)2017-02-09

For all those who have had issues with the links, they are now fixed

thanks for the feedback

Jackson123 (author)2017-02-09

People who comment, "But I can buy something even better for less money" really don't understand what Instructables is all about.

AdamR13 (author)2017-02-09

Don't get discouraged by the worms who try to discount your work or cry foul. They don't matter a bit! Your brave enough to post your awesome work and take the time to try to teach others. You even post theist of parts and the average costs which is also awesome.
I for one, thank you for taking g the time to do this at all.
Just ignore these fools who never have a kind word. Just know those who take the time to make jokes and flame your hard work are probably full grown adults still living in mommy's basement for free. Spanking Hank because that is ALL THEY ARE GOOD AT. Lol.
This is a great Instructibles and I thank you for taking the time to post this information! Nice job!
ilive4fun biotch-slaps these tardlings who have nothing nice to say, for you!
Keep up the great work!

lawrence.rhodes.3 (author)2017-02-09

I guess what my idea is is you amazing light is great for 30 minutes but I'd take something less expensive that is normal bright for many hours. Simple math equation to figure out run time. One option is maybe the adjustable brightness and energy consumption modulation. Run at 100 Lumens for a day or super bright for a short time.

geopro (author)2017-02-09

Couldn't you just use three 11.1 volt Li-Po batteries, giving you 33.3 volts, keeping it under the 34 volt max current, producing a lot longer run time and most importantly, the ability to eliminate the boost converter and likely the digital meter too. Or am I missing the obvious. Either way, a great outrageous project.

BG17 (author)geopro2017-02-09

No, 11.1 is the rated voltage, a fully charged cell will be much higher and blow the led

geopro (author)BG172017-02-09

OK ... got it, thanks for the tutorial

BG17 (author)geopro2017-02-09

"34 volt max current"

you need to read this

gabriellero22 (author)2017-02-09

Looks cool. I could use it when i go to girls camp. i am into making my own tech and this could be a fun activity! Thx!

Iwannamakethattoo (author)2017-02-09

I think any negative comments like the one just below should be just ignored. It's amazing and just for The experience and joy of trying it, it I'm gonna try to do this thanks for the inspiration and all your work!! Some people JUST DONT GET IT!!

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