In this instructable I'd like to show you how I made this really powerful flood/spot light, which features huge coaxial lens for focusing, as well as it can output up to 10k lumens with correct LED used. So let's see how its made.
Step 1: Gathering All the Parts
The parts list:
Enclosure - For this project, I decided to go with a metal box from Four Roses bourbon, as it has nice dimensions, and is quite sturdy.
LED - I went with cheap ebay 20w warm white led, these are cheap and you can get them for under 3$
The reason this project name has "2-10k lumens" is, that you can choose, whatever LED suits your needs. I also have a 100w cool white led, which has 5x more light output. However, that light output is fairly unpractical, as its almost too bright to use anywhere indoors, and also our 150Wh power pack wouldn't last as long. This way I can get between 6-8 hours of run time
Driver - I'm using ebay boost converter with XL6009 chip, to boost the voltage to around 28 volts. I also added a piece of old aluminium heatsink, together with some thermal grease, and stuck it under the chip part of boost converter using some enameled wire (insulated, be sure to check it if you want to do it the same). It would also be possible to stick it onto the back part of LED's heatsink, but if you decide to do so, make sure that it's insulated well.
I also did a few tests to check temperatures, with no active cooling, driver won't go above 40°C and led above 35°C, after 10 minutes of run time.
Battery pack - I used 15 fairly new 18650 Li-Ion batteries, salvaged from "new" (old, but never used) laptop batteries, theese were my better cells, as they were no longer than 1,5 years old. Original capacity was 2,6Ah per cell (3,7v nominal, 4,2v fully charged, 3v discharged). For 15 batteries, I'd say that this battery pack does easily supply 150Wh of electricity. I used some plastic 18650 holders from DealExtreme.com, because everything there is cheap and ships for free worldwide (however its slow). I soldered them all in parallel, to use simple 18650 charging circuit. This pack has 4.2v fully charged, and can deliver up to 50 amps, with correct wires. I don't own a spotwelder, thats why I had to solder them manually, which turned out to be ugly but working solution.
Charging circuit - For this to be simple and reliable, I went with TP4056 charging circuit. It can charge at 4.2w power, using any MicroUSB phone charger. It takes plenty of time to get it fully charged from zero, but the simplicity and being able to simply plug this in overnight and have it charged is awesome. I also think that with 6-8h of runtime, this won't suddenly turn off when you need it. When I'd need a fast charge, I'd simply get the pack off, and hit it with iMax b6 4,2v 4A charge. Also, this way you can get something like a Xiaomi Powerbank (10400mAh), hide it inside of the case and have it working again in just a second, as this is able to charge while lighting. However, when lit, the charger will only slow down the discharge speed, as its power is insufficent for charging while being operated.
Lens - To make this light focusable, because 170° flood is not always the thing we need, I bought a cheap $3 hi-power led convex lens from ebay. I wanted to make this thing able to direct all of its power in tight angle, so that I could easily see things from distance. And even tho the lens with its fairly small reflector doesn't provide the best throw, its still able to fully illuminate everything within 100-150m range. With 100w led, I bet it would be at least triple that distance. I also wanted to make it easy to focus/flood. I tried all the "normal" options of mounting the lens, which normally consists of 3 parts (lens itself, reflector and bracket), but none was easy enough to put the lens on and off. So I took a bit of inspiration from DIYPerks channel on youtube, which I love so much, and used somewhat similiar straps to hold it in place. It is not the most beautiful solution, but its easiness and the fact that I'm using it mostly unfocused and I can store the lens inside of the box really made me go this way. You can put it on in less than 10 seconds, its that easy. The lens bracket is also holded with 4 small pins that fit into the LED's corners, so its sturdy enough to don't slip off randomly.
Heatsink - The one that I'm using is old Pentium/Dual Core E2100 cooler, without the active fan. The led is held in place with stiff enameled wire, that leads from the mounting holes on the led to the sides of the heatsink's mounting legs. Its simple loop, with the end twisted with a pair of pliers, until it holds enough. Just make sure the led is touching the heatsink with its entire back, or apply some thermal grease to be extra sure. I'm currently with no thermal grease between those, and I'm having absolutely no thermal issues. The beauty of 20-30w leds is, that they can be cooled fairly easily with good aluminum heatsink, if you decide to go with 50w, you might want to use active fan + some vent holes, for 100w led this would be a must. Another boost converter will also be needed if you decide to go 50w+.
Switch - I used a simple lever switch, as it was very easy to mount into a simple drilled hole with a nut. Be sure to use a switch appropriate for your LED current, as 100w leds could easily melt the inside of small switch, as it needs up to 4A of current. It wouldn't most likely happen immediately, but if operated for longer periods of time, I experienced the inner wires melted together due to too much current. If that happens, the switch might get stuck in ON position, unless you'd tear the soldered leads off it.
Voltmeter - As this battery inside has no inner protection circuit, you have to look at battery level indicator from time to time, as overdischarging Li-Ions drastically decreases their lifetime and inner chemistry safety. The easiest battery charge indicator for me was a simple $1 ebay voltmeter, which is inside of the box. I also considered having the display visible from outside in a slit cut into the box, however that would decrease the water resistance, and because of the voltmeter being a fairly precious component, I decided to keep it inside. It has also a switch to turn it On/Off, to save the energy from being drawn all the time.
Handle - Very important part to get mounted properly, because if not, this not-the-lightest flashlight might want to fall and damage itself. And thats not what we want. To not hold it with simple nuts in the box, as it is not sturdy enough, I mounted a piece of wood to spread all the pulling tension on larger area. The wood also helps to keep the powerpack snug in place.
Step 2: Prepairing the LED
I mounted the LED onto the heatsink with stiff enameled wire, as written above, soldered some braided copper audio wires, used plenty of heat-shrink tubing and double checked for no shorts, as our powerpack would probably melt all the solder with hard short, because its short-circuit current might go as high as 6A per cell. And 90amps is alot. The wire is then stuck between bended fins on the sides, to relieve some of the tension that might ever want to tear the wires off the LED. I drilled holes on the bottom of the box, but be careful. The circular drill bit is very bad idea for this. I tired it, and once it broke through on one side of the metal, it bent itself on the part that was still connected to the rest and screwed the entire hole. I'm glad I was able to partially rescue it with some filing and patience. Because I wasn't able to find any good screws and nuts to match the heatsink and the holes, I simply riveted it, and IMO it looks better than any screws. It holds it very sturdy, and the heatsink fits perfectly the size of this box, as it does not touch any of the sides. You can see that on the attached images. It is also important that the led is as close to the opening hole as possible, to keep the wide angle flood.
Step 3: Prepairing the Battery Pack
I decided to use 15 18650 batteries parallel, as that provides great lifetime for this LED. I could easily fit two of these packs inside, but that would requiere a better cable management, than what I'm currently having in. (It works, but its terrible mess for anyone who doesn't know what he's looking at.) I've used some wires to solder them all (get a spotwelder if you can, or at least flat wire to connect them all), and then I also decided to reinforce the leads, so that I can possibly get more power out of this pack if I need to change the LED. It is capable of 50+ amps with no big problems, so the wires should be somewhat adequate to that. I also did not use more 18650s, not because I would not have more, but because in single shipment of the battery holders from DealExtreme I recieved only 10 pieces of holders, each with 3 slots on its side. That equals to 30 slots total, which accomodates 15 batteries. Simple math.
The batteries I'm using are 12 Sanyo 2600mAh cells, salvaged from fairly new laptop battery, the 3 green cells are Sony 2200-2400mAh (not really sure there). I'd assume that each should be at 2-2.2Ah at least, didn't measure this, but any differences are thanks to the parallel desing of the pack don't matter, as the current always spreads on the batteries, so all are at the exact same voltage. Also you don't need to solve any cell balancing, as would be necessary with any 2,3,4s or whatever packs with series connections. You could simply use something like Zippy Flightmax 3s 8000mAh battery or SLA (sealed lead acid) batteries instead of this way of powerpack, it is definitely up on you what wou want. What I like on all Li batteries over SLA is that they're really light per Wh stored.
I'm simply using TP4056 module as charger, thats described in partslist. However, meanwhile I'm writing this instructable, I'm recharging the pack, and it seems that it pumps more than 4.2watt inside, as the voltage is rising fairly fast. I would even believe this can output like 8 watts. However, when I try to connect amp-meter to the circuit, the TP4056 won't longer recognize a battery and will terminate the charge and light up the blue LED.
Then I used a piece of cardboard, to protect the pack against shakes, make a snug fit inside and also to insulate the sides. Its ugly, but it works.
I also added a voltmeter, which can be turned on or off. First I wanted to make it a 3 position, with readings on battery pack, driver output and switched off. However, the driver boosts the voltage still to same level, no matter the powerpack level, so I removed that.
The pack is fully charged at 4.2v, and fully depleted at 3 volts. But I would personally go charge at anything under 3.3v, as it is not good to keep Li-Ions at this level for long time.
Step 4: Assembling It Together
It is very simple. Just solder everything together, be sure to use heat-shrink everywhere, wrap the driver (boost converter) with some electric tape (I ran off electrical tape, so I used multiple layers of scotch tape, having only the heatsink fins exposed) stick the powerpack inside, make sure its snug, fit the switch into its position, stick the rest of the cables inside and you're done. I'm also planning that I would use some superglue to get the voltmeter, voltmeter switch and charging module on place, close to the opening. But I don't really care, as it is still really easy to fish out any of them.
The battery pack stays stable in place, but only direction in which it can move is towards the opening. For a very simple solution, I cut few sheets of paper to exact length, rolled it tight and wrapped it in scotch tape. Just throw it in and you can point it anywhere. I found this solution to be much better than I first expected, and it doesn't even wobble around, thanks to the snug fit between the pack and back door, and the cables around it.
Step 5: Putting Together the Lens and Strap
I wanted to make this thing easily focusable, but the way the bracket is mounted normally simply won't allow me to do so. So I used superglue to get all the 3 parts of the lens together, attached some straps with a rubbery piece in between, to put some pretty good tension on the lens once it is in place. The strap is sewed at the ends, then I used some zipties to gold it equally strong on all corners and used some superglue to make the straps on permanent position on the zipties. Very quick and easy solution.
I also thought of making some extensions of the bracket with screws, drilling small holes in the ends and supergluing small neomydium magnets inside of them, so that you could easily snap it onto the metal case. However, I had no appropriate neomydium magnets around, and also I'm using this light mostly without the lens, so there was no reason for me to do it the hard way.
The lens provides us with very nice option to direct most of the light in much tighter spot, from 170° flood to what I'd say is like 60-65° spotlight. I can easily get things in 100m range visible, but this is where simple XML-T6 flashlights can outshine this light thanks to their much narrower beam angles. But if used in close environment, this light can't be outshined by any "normal" flashlight. (There are few extremes, like those 6x XML-T6 Skyray King flashlights, that can do up to 8k lumens, but thats not something that normal people would use, just because their battery life on 4x18650 sucks so bad.) So you can consider this thing best portable light for whatever occasion.
Photos - as you can see on the 2 photos, those are the lighting results with light in 2m distance. It is also located a bit to left from me taking the photos The brightness is inaccurate on these photos, as I'm shooting them with a smartphone, and it automatically ajdusts the ISO and exposure. But I can tell you, that these lights are really bright. You can see that without the lens it has really nice, almost softbox-like spread, with realistic colors on the object illuminated. On the other hand, the lens adds it noticeable yellowish tint, and also the spot is illuminated with a sort of shape of the emitter itself. If you own any hi-power focusable flashlight, you know this effect, however its less noticeable there. The quality of the light through the lens is much worse for shooting videos or anything similiar, but just for the purpose of long-distance illumination it does the job done really good.
Step 6: We're DONE!
I must confess, that when I started this project, I did not expect much from it, but now, I'm really satisfied by how good the light is and also the runtime is outstanding with the 6-8h time. I'm able to charge it from fully depleted state to full in less than 20 hours (more about this in the description of charging circuit) with nothing else than only MicroUSB charger for your smartphone! I also tested this with extra switch connected back in prototyping phase, that allowed me to run the LED only on USB charge with no batteries involved, however at decreased light output to about 5-8watts. Thats still over 500 lumens of light! With battery power, this should have light output of somewhere between 2-2,5k lumens, but this LED can also be overdriven up to 30watts, with good heatsink. That would add another 1-1,25k lumens, but I prefer the long runtime, as the output is still crazy high. Outdoor use for Geocaching and stuff, this can create you almost a daylight in few meters range, and allows you to throw it anywhere you need and do everything with both hands free, thanks to its flood and light intensity. It is fairly light, its weight is just like a 1.5L bottle of water. Its fairly modular design also allows you to change any part if anything goes wrong, you can change the LED chip in front in less than 40 minutes with soldering iron nearby, and also get multiple battery packs if you're using LiPo packs and connect them with something like XT-60 connector.
What I also love about this light is how soft the light spread is, so if you're working in environment where getting a proper softbox for shooting videos is a problem, this does the job done fairly well, considering how cheap it is to make. You could possibly even place a GoPro sticky mount onto the top of the casing, to get some nice night footage.