Five Watt 1 LED High Power Rechargeable Flashlight




Introduction: Five Watt 1 LED High Power Rechargeable Flashlight

Whether you just need a high powered flashlight for long range illumination, a headlight for riding your bike in the dark, or simply want to outshine the competition, this will show you how.

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Step 1: The Materials and Cost

1 - Five Watt High Power Luxeon Star LED $7

8 - AA 1.2 volt NiMH Rechargeable batteries $6+ (depending on brand)

1 - Eight AA battery clip (4 rows of 2 batteries) $2.50

1 - small piece of aluminum foil a couple cents if you already have some

1 - 3 x 5 notecard a couple cents if you already have some

1 - roll of double sided tape $1.50

1 or 2 - stick(s) of hot glue ~$2 for a small bundle

1 - aluminum heat sink (salvaged, or new) $2-10 (depending on size and seller)

1 - switch or button a couple cents

some wire a couple cents

1 - package of high strength glue (i used JB Weld) $5-8 (this is only necessary if you use the lens

1 - focusing lens large enough for the head of the flashlight (I salvaged this from an overhead
projector, so I am not sure of the price)

Multiple resistors of different values (preferably 1/2 watt), or one 3.9 ohm resistor with a 4-5 watt

1 - small tube of thermal compound grease $1-2

1 - 9v battery clip (optional)

total: roughly $27 depending on what you already have and what brands you buy

(for the batteries, thermal grease, and LED, I suggest ebay. the rechargeables are very cheap, but ive been using them for weeks with no problems yet)

Step 2: The Reflector

take your aluminum foil, double sided tape, and not card.

take the tape, and cover the note card in rows or tape. then, carefully lay down the aluminum foil (shiny side up) onto the tape and smooth it down. With a pair of scissors, remove the excess aluminum foil from the edges of the card.

on the five inch side of the card, cut halfway though to the other side.

Overlap the two folds of the cut onto each other to make a cone (be sure to have the aluminum foil on the inside of the cone) (the tighter the base of the cone is, the tighter the light beam will be)

with your scissors, cut a hole off the tip of the cone large enough for the entire LED to fit through (just the LED, not the small aluminum heat sink that comes attached to it)

Trace a circle around the inside the note card to create an even guideline for trimming the excess paper.

Step 3: The LED

Solder one wire to one of the positive leads and one wire to one of the negative leads. If you like symmetry, you can also solder wires to the other leads as well.

After doing this, push the LED through the hole in the cone so that the LED itself is on the side with the aluminum showing, but the heat sink that came attached to the LED is on the outside of the cone.

once the leads are wired, add a bit of hot glue to keep the cone pointing straight and connected.

Step 4: The Heat Sink

This step is very important. it is crucial that you use a heat sink that can dissipate all the head from the LED with ease. The one I am using was from a broken computer power supply and works well enough that even after extended use, the heat sink doesn't heat up any noticeable amount, not does the LED.

mount the LED onto the center of the heat sink with a small, evenly spread amount of thermal compound grease. What I did was to spread a small drop onto the aluminum heat sink, the placing the LED on top of it, and swirling the LED in a circle until the grease was evenly distributed.

simply pressing the LED straight down onto the grease doesn't seem to cut it.

Step 5: The Resistors

In this step. you will need multiple resistors of varying values. I have found that by adding resistors together parallel to each other, I can get the exact correct value and plenty of extra wattage protection.

For this circuit, you will need a 3.9 ohm resistor capable of dissipating 2.2 watts. But to be safe, and to keep the amount of heat generated more widely dispersed, it is best to go with 3-5 watts.

(if you plan on using a different battery voltage (other than the 9.6 volts from the 8 rechargeable batteries, you can calculate the value you will need here: <> )

I have 13 1/4 watt resistors, which means that the bundle is capable of dissipating 3.25 watts.

I am sorry for the little amount of instruction I can give here, but all I can say is that you need to bundle resistors until you have 3.9 ohms of resistance. Just make sure not to use any that are below 3.9 ohms.

use 12 or more 1/4 watt, 6 or more 1/2 watt, 3 or more 1 watt, 2 or more 2 watt, or if you are lucky enough to find one, 1 or more 3+ watt resistor

Step 6: Assembly

First step is to glue the edges of the LED onto the heat sink to prevent it from sliding around.

Making sure to have wires soldered onto the positive and negative ends of the LED, use some good glue, such as JB Weld or JB Kwik ( I used JB Weld, and it hasn't failed yet)

Next, secure the reflector cone onto the LED by arching some glue from the edges of the cone to the heat sink as shown in the picture. I highly suggest JB Kwik as it has all the strength of JB weld, but it sets fast enough so that it wont be much of a trouble to wait for it to dry.

Attach the battery clip to the battery holder, and solder the red (positive) wire to the resistor pack with an ON/OFF switch or a button switch somewhere in the middle.

Use a bit of hot glue to attach the resistors onto the battery pack (next to / parallel to the battery clip).

Solder the black wire of the battery clip to the negative lead on the LED (if the black wire reaches that far) or solder it to the wire that is connected to the negative lead on the LED.

Finally, glue the heat sink and LED onto the top of the resistors and battery clip, and glue the switch / button somewhere convenient on the battery pack.

Step 7: Enjoy

The battery pack should last roughly three hours. I have found that it stays at full or near full brightness for around two hours, but I haven't tested it any further than that yet without recharging.

Don't forget, if you want the light to be focused as it is shown here in this photo below, try to find some salvaged lens that would fit the reflector cone.

The photo below doesn't give too much credit as to how bright the flashlight is.

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    13 Discussions


    10 years ago on Introduction

    Crees put out more light per watt than the luxeons. I think an r2 can do 200+ lumens for 3 watts


    Reply 10 years ago on Introduction

    r2 does easily 200lm. Wattages are NOT the way for measuring light output. it's the stress on the batteries. My Fenix LD01 does 80 lumens on a single AAA battery. it's amazing.


    Reply 9 years ago on Introduction

    Clearer to say lumins is the measure of visible light

    So by using an array of 99 LEDs can I get a beam powerful enough so that it can be used as the headlight on a Motorcycle?

    Zen Innovations
    Zen Innovations

    Reply 9 years ago on Introduction

    Stop wasting time with 5mm LEDs. They're complete junk, only suitable for Toys, Indicators etc. If you need some practical illumination, look at SEOUL p4 Z-LED which are now available in Bombay. 


    Reply 10 years ago on Introduction

     you should be all set, yes. I have a flashlight using 48 that is about 2/3 the brightness of the flashlight from this instructable.

    I am not sure how many lumens each of those LEDs produces, but if yours are capable of 20 lumens each, your motorcycle should be quite adequately lit.


    Reply 10 years ago on Introduction

    assuming that you are using 3.6 volt LEDs, your best option would be to use only 99 LEDs. this would let you set up an even array of 33 parallel series of LEDs with 3 LEDs per series.

    you would need 68 ohm resistors for this setup. if you'd like to see a diagram fo this, just go to:
    and enter your information

    Unfortunately in my place we don't get any Cree LEDs. But can I use an array of 100 LEDs of 20 lumens each to produce an overall 2000 lumens? If yes, how can I connect these LEDs together and which resistor should I use for a 12V power supply? I desperately want to make LED headlamps for a motorcycle ; (

    So you mean that with the appropriate lense or reflector I can use them as primary headlights in a motorcycle!!!


    Reply 10 years ago on Introduction

     most definitely. although, as another commenter mentioned, cree does have a better wattage-to-lumen rating.

    I highly suggest that you use the Cree XR-E led. You can get them on eBay for $4, and they have double the output.

    Using the same battery setup (from my instructable) with an XR-E, you would need to make the resistor capable of dissipating 7+ watts.

    That being the case, I suggest running the XR-E at 700 mA using a 3.6v battery pack (using batteries in increments of 3 (either 3, 6, 9, or so on) 
    That way, you would be able to run the led at around 200 lumens. You would need a 1+ watt resistor in this configuration.

    hope that helps, and good luck!


    Reply 10 years ago on Introduction

     Through the lens, or with a reflector angled around 50 degrees, I could get roughly 100 feet (~30 meters)