100W LED in PVC Flashlight

Intro: 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: https://www.instructables.com/id/100w-LED-Flashlig...

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.

Disclaimer:

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

Solder

Heat shrink or Electrical tape

Supplies:

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.

Comments

[redrooster]

Could you use a metal pipe instead of plastic so that it could double as a heatsink?

[DakLak]

An alumin(i)um tube would be best as that metal has superior heat conducting propertoes.

[jaksherry]

I don't see why not. but take into consideration that it would likely be heavier and mote expensive. also, be very careful about sealing the electrical connections or the tube could short it out. Good luck!

[Charles Gibbs]

And also< I would like to see how long your going to hold on to that tube with 100W dissipating form it..... :-O

[redrooster]

I would use a computer heatsink for the LEDs and a thick walled aluminum pipe for the battery,fan,etc... the fan would draw the heat away from the heatsink along the inside of the pipe and extract it out the back,so the pipe is dissipating the heat as well.Beats plastic for this application.

[Charles Gibbs]

Hi redrooster, yes as did I, scroll down further and read what I did with my 100w chip and a CPU heat sink, as I say it has been running for two years now no probs, its not portable as such but I use it on camping trips and in roofs etc..

Have a blessed day.

[hanelyp]

If the tube doubling as heatsink is too hot to hold, it's not really getting rid of heat fast enough for the LEDs.

[hanelyp]

If the tube doubling as heatsink is too hot to hold, it's not really getting rid of heat fast enough for the LEDs.

[Tanishq Jaiswal]

From where you got the step up transformer ?

[PhilKE3FL]

Another tip & a question, First the tip: When using heat sink compound you want to use as little as possible. If you can see it clump up you're using way too much! Use your finger and wipe it all off till you can see a sheen but no clumping, do this to ONE side only. The object of heat sink compound it to fill in the gaps NOT to place a buffer between the two surfaces. You want the two surfaces to touch in as many places as possible with NO heat sink compound between them. The perfect join, using no heat sink compound, could be obtained IF we could machine the two surfaces to join together perfectly. (This can be done, but is still cost prohibitive for our purposes.)

Question: Is this "100 W" LED an LED that puts out the equivalent of an old style incandescent 100W bulb, or is it really using 100 W of power?

[jaksherry]

First, thanks for the tip.

To answer your question, I believe that the LED module has 10 rows, each row has 10 1watt LEDs.

[PhilKE3FL]

To get 100W from 14.4 Volts (12 * 1.2) you need close to 7Amps, for 2.5 AHr batteries they last about 1 minute at most probably less. This is from a calculation & I reduced it with a bit of guess work. So, how long to they last?

For 2.5 Ahr batteries I believe that the rating is determined using about 125 mA (for lead-acid batteries the Ahr rating is determined using a 20 hr discharge rate so 2.5/20 = 0.125A) 7 Amps is 56 times faster and the faster a battery is discharged, above the 20 hour rate, the more the life of the battery decreases. So if it were perfectly linear we would divide 2.5/56 * 60min ~2.7 min, and 56 times faster than the the normal 20 hour rate would decrease the life even more so I estimated it at 1 min.

[Charles Gibbs]

Hi All!

What I on occasion have done (with great success I might add) is to take a bit of ultra fine rubbing compound on a super soft cloth with water and lapped the heat sink and LED chip and then put just a dab of heat sink compound on the LED chip and pressed them together with a cloth on both sides so nothing gets fouled up and once that is done I took Q-Bond which is a form of super or crazy glue depending on what you want to call it and traced the edges of the LED chip. This bonds both surfaces permanently and because you have basically lapped the two faces and used minimal heat sink compound heat transfer is aces! You have to make sure to use as little heat sink compound as possible though, once this stuff contaminates a surface it a bugger to get clean and then the glue does not stick, be very careful when matting these two items as there is a big and very real chance of damage happening to the LED chip. But, sitting in 40 degree C heat I must say I have had no problems with heat build up or transfer and my chip has been working for close on two years now. As far as maintenance goes, I just make sure that my heat sink remains clean and that my fan is in good working order, the heat sink I chose was from a computers CPU probably overkill I know, but, out here those things are way pricey so better safe than sorry.

Charles Namibia.

[david.roseman]

Scratching the heatsink is exactly what you do NOT want to do. You want a polished surface to avoid any discontinuities in the gap between the LED and the "heat sink".....also, JBweld?! If you want to have little to no thermal condutivity between the LED and the heatsink, you can use JBweld, else, use all thermal grease, or thermal epoxy. You need to get that heat out of that COB!

And so on about the lack of heatsink, but everyone already mentioned that.

[jaksherry]

Thanks, noted. Will keep in mind for future builds :-)

[darksb3r]

Absolutely correct - lapping the heatsinks and the mating surface is the solution. The flatter the mating surfaces, the better the thermal conductivity. The thermal grease/epoxy is just there to help fill the inherent gaps formed from the polishing process.

Take a look at this chart of the thermal conductivity of different materials (JBWeld is 0.59 W/mK!)

http://reprap.org/wiki/Thermal_Conductivity

It is at least a little better than air, hehe.

[Lee Wilkerson]

Great idea, but what in the world are you going to do with a 100W flashlight (spotlight?) any way? I'm thinking a 10W flashlight would be plenty and the 10W/900 Lumen LEDs SKU060051 which I bought require 12 VDC to operate. I purchased them from banggood.com for $0.59 each. You could even place 10 - 10W LEDs in parallel if you wanted more light or use a selector switch to select 1 or multiples. This eliminates the DC/DC converter which means less power consumption and it also eliminates the shock hazard.

Use 140 grit or higher sandpaper or sand cloth to roughen up the surface of the metals. This will render far more surface contact resulting in much better heat dissipation.

[jaksherry]

Thanks for the interest! I have NO need whatsoever for a 100w flashlight. I just like to tinker :-)

[Lee Wilkerson]

Great idea, but what in the world are you going to do with a 100W flashlight (spotlight?) any way? I'm thinking a 10W flashlight would be plenty and the 10W/900 Lumen LEDs SKU060051 which I bought require 12 VDC to operate. I purchased them from banggood.com for $0.59 each. You could even place 10 - 10W LEDs in parallel if you wanted more light or use a selector switch to select 1 or multiples. This eliminates the DC/DC converter which means less power consumption and it also eliminates the shock hazard.

Use 140 grit or higher sandpaper or sand cloth to roughen up the surface of the metals. This will render far more surface contact resulting in much better heat dissipation.

[Lee Wilkerson]

Great idea, but what in the world are you going to do with a 100W flashlight (spotlight?) any way? I'm thinking a 10W flashlight would be plenty and the 10W/900 Lumen LEDs SKU060051 which I bought require 12 DC to operate. I purchased them from banggood.com for $0.59 each. You could even place 10 - 10W LEDs in parallel if you wanted more light or use a selector switch to select 1 or multiples. This eliminates the DC/DC converter which means less power consumption and it also eliminates the shock hazard.

Use 140 grit or higher sandpaper or sand cloth to roughen up the surface of the metals. This will render far more surface contact resulting in much better heat dissipation.