Introduction: 100W LED in PVC Flashlight

This is a modified version of the 100W LED flashlights on Instructables. I have looked at several of them.

While they look really great, none seem to have portability, and they all use massive, heavy, expensive batteries.

I developed this project over a few days while trying to make it more portable, using common rechargeable batteries.

Credit to:

This light does drain batteries rather quickly, and is really more proof-of-concept than actually useful as a utility light, but I really enjoyed designing this and putting it together. I hope you do as well, or at least get some good ideas out of this.


This device will use a high output voltage. BE CAREFUL! Basic safety steps (such as rubber gloves, etc) can be very useful.

This light is EXTREMELY BRIGHT, do not shine directly into someone's eyes. Trust me, it will hurt.

Also, it should be mentioned that rechargeable batteries carry a voltage of about 1.2V, while alkaline batteries are 1.5V. Do not mix these batteries or the resulting output will not match. This project can be done with alkaline batteries as well, and less batteries will be needed. But it would cost more $ long-term and you would be less green. Shame on you for even considering it.

UPDATE: I thought that I was not outsourcing the heat properly and some LEDs burned out, but what actually happened was that all LEDs work just fine. After reading the batteries with the multimeter, I see that this light works perfectly, but it does drain the batteries rather quickly. In the future, I will hopefully be putting out an instructable with an ungraded light output and more efficient heatsink.

Step 1: Supplies

Tools List:

Small Flathead Screwdriver

Drill + bits

Rotary tool (like a Dremel) or Hacksaw

Wire stripper/Crimping Tool

Digital Multimeter

Dry Silicone Spray (optional, but worth it)

Soldering Iron


Heat shrink or Electrical tape


100w LED

44mm lens+ reflector kit

Colored Wire (red and black)

Step-Up Transformer

12V Power Switch, preferably lighted

Thermal paste

JB Weld Epoxy adhesive

12V 40mm fan+ heatsink

2” PVC pipe

2” Cleanout plug

2” Cleanout Adapter (2)

1 ¼” PVC Pipe

Two 1 ¼” PVC End Caps

4 Nuts

2 Bolts

2 Ring Wire Connectors

4 AA-to-D size battery serial converter to 4.5V

12 AA rechargeable batteries

The total cost for me was about $20, but I had a lot of this laying around except for the step up transformer and reflector kit. If you are buying all from scratch, it would probably cost closer to $35.

Step 2: Making the Battery Pack

The input voltage for the LED is 34V, but we will do it using the step-up transformer. In order to do that, we need a special battery configuration.

Side note: PVC tends to cut with rough edges. Smooth everything down between steps so nothing tears (ie wires or your skin).

1) Take both 1.25" end caps and drill a hole as close to center as possible that will fit the bolt.

2) On ONLY ONE OF THEM, drill a second hole on top, about half an inch or so away from the first hole. This will be the positive end.

3) Crimp the ring style terminals onto the wires. Easiest to remember of you are using red for + and black for -, but you can just use whatever you have available if need be.

4) Attach the positive ring terminal to the outside of the hole on its end cap using the nut and bolt.

5) Attach the negative ring terminal to the inside of the hole on its end cap using the nut and bolt.

6) Measure and cut your 1.25" PVC pipe to fit the 4 battery converters inside it, fitting snug with the end caps on. On mine, it was 7.5", but it may be slightly different depending on your exact converters.

7) Load the battery converters with your rechargeable AA's, and assemble your new battery casing, with the negative wire inside the tube, poking out of the second hole in the positive end cap. The picture does a better job of describing this.

8) Measure output voltage, it should be in the realm of 14.4V. These batteries were freshly charged so it ran a little higher.

Step 3: Configuring the Main Tube

1) Cut the 2" PVC pipe to about 19". Smooth the edges.

2) Scratch up the flat side of the 40mm heat sink/fan, and scratch up the backside of the LED module.

3) Carefully mix together the JB Weld Epoxy, and mix in a little of the thermal paste. About a teaspoon of epoxy with literally 1-2 drops of thermal paste should do it.

4) Attach the heat sink to the LED module using the mixture of paste, and let sit for 24 hours to fully cure.

5) Drill a hole in the 2" PVC tube to fit the power switch. (I prefer a lighted switch, because it cuts troubleshooting time in half. If the light does not turn on when you press the switch, you know the problem lies before the switch. If it turns on but the device does not, you know the problem lies after the switch.)

6) .Screw one cleanout plug to a cleanout adapter and spray the inside lightly with the silicone lubricant spray. This will be the battery end of the tube, and the silicone will help make that end easier to put on and remove so you can recharge the batteries using your standard AA recharger.

7) On the other cleanout adapter, drill 4 tiny holes (otherwise it will crack) to match up with the holes on the reflector kit.

8) Set up the step up transformer by attaching the 14.4V battery to the input. Then attach the multimeter to the output, and rotate the screw using the small flathead screwdriver until the output reads 34V.

9) Assemble the electronics using the diagram above. Keep in mind that there is polarity on the LED module, so you need to keep track of which side is positive and which is negative.

10) Now slide the electronics into the tube, with the battery pack on the end with the cleanout plug, and screw the reflector kit into place. When the batteries run low, you can just take them out of that end to charge them, and the rest of the electronics should never move.

11) Now shine a light, you crazy diamonds! Please feel free to comment with any questions.

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