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
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 - Amazon.ca
11.1v LiPo Batteries (chose whichever apply best to your uses)
Balance Charger Cable Extension - CDN$ 2.04 - Amazon.ca
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
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
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
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
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).
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.
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
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
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!