Intro: Efficient LED Bike Light System
This is the most efficient method of lighting your entire bike.
What you see in the photograph is only 8 LEDs that run for hours on 2 AA batteries (excluding the red tail light, which is separate).
Say goodbye to cold cathodes and huge strings of many LEDs: this method uses single LEDs to illuminate entire "neon tubes." Here I also make use of the simple features of my bike - reflective surfaces that make the best use of single LEDs by reflecting the light in all directions, illuminating the bike and increasing visibility on the road.
One LED can go a long way; why not use them all that way and create a setup that shows off the most light for the smallest amount of LEDs.
This Instructable can be used more as a guide than exact instructions. I will show you how I wired LEDs and plastic tubing to get a glow stick effect, underglow, and more.
Step 1: Get the Supplies
You need a cheap source of LEDs and some polyethylene tubing, which can be found at hardware stores.
I highly recommend Best Hong Kong as your source of LEDs. The shipping is surprisilgy cheap, and is worth waiting a few weeks for. Mine usually come in just a couple weeks. They sell loose LEDs of different sizes, colors, intensities, etc.
What you need, specifically:
- 5mm, high-intensity LEDs. Choose your colors and intensities, but make sure they can operate at 3 volts. At Best Hong Kong, each LED has its own description that tells you its operating voltage range. Make sure 3v is within this range.
- Polyethylene tubing, 5/16" inner diameter. Make sure this is high density polyethylene (HDPE), and is in its natural color (semi-opaque). I got mine from a friend, but you can look for it at hardware stores like Lowe's. See this example of what the tubing looks like.
- Electrical wire. I won't get into gauge, but a good thickness to use is what you might find on the inside of a keyboard or USB wire. I have in fact used these to wire some of the LEDs on my bike. When you get a keyboard that no longer works, cut the wire off, and carefully strip the insulation off till you can get the 4 multi-colored wires that are inside.
- Electrical tape. Use the good, expensive 3M brand, as it sticks well and doesn't seem to come off even after hundreds of miles and rainy weather. By "expensive," I mean around 3 bucks. So from a broader perspective, it's really cheap.
- Packaging tape. Again, use an "expensive" kind that will stick well and not get torn up. I only use this to help keep the plastic tubing stuck to the bike; it is not required.
- Hot glue & glue gun. You will definitely want this too. I use cool melt, so I don't accidentally melt some plastic part or tape.
- Soldering iron and electrical solder. I use a very cheap iron, the tip of which is almost completely eaten down and needs replacement. Still, it works fine.
- Altoids tin. Of course, everything is made with Altoids tins! This will be the housing for the batteries and switch.
- Springs for two AA batteries. I suggest tearing apart an unwanted device that uses 2 or more AA batteries. Take the springs out to use in the Altoids tin.
- Switch. Some kind of electrical switch; whatever you prefer. Just something to turn the lights on and off easily that you can solder in-line with one of the wires.
That's all that I can think of. You don't have to make your system just like mine; like I said, this is more of a guide than exact instructions. Be creative and come up with whatever works best for you.
Step 2: Altoids Tin Setup
Set up your Altoids tin so it holds 2 AA batteries, a switch, and a connector (I used a Deans connector).
I mounted the tin to my bike by screwing a bike reflector mount into the back of the tin. It holds the tin just like it would hold a normal reflector, and provides easy access to the switch during riding.
Step 3: Get the LEDs
Use LEDs that can operate at 3.0 volts. The max voltage should be no less than 3 volts and no more than 3.4 volts for best results. You will be running them on 3 volts straight, with no resistors or other extra components (unless you want to take this a step further).
Step 4: Neon Tubes!
This is the difficult part but is the most important.
Some use cold cathode, some use a series of MANY LEDS to get the desired effect. However, I use only 1 LED per tube.
Insert a 5mm LED into one end of the HDPE tubing, and hot glue it securely in place. If the LED fits loosely into the tube, make sure you glue it as straight as possible so it shines straight through the tube and not off to the side.
Un-bending the tube is difficult. You will need as straight a tube as possible, in order for the light to shine all the way through and light up the tube.
Some suggestions for straightening the tubes are:
1) The surface on your bike on which you will be attaching the glow tube must be perfectly straight.
2) Glue the tube to your bike using hot glue or epoxy, and then tape it in place with clear packaging tape to keep it from popping up - it will try to become bent again and may break loose from the glue.
3) Keep the tape on for extra reinforcement. Make sure you use high-quality, clear packaging tape as it will stay on for a long time.
Solder the LEDs to color-coded wires (remember, LEDs are polarity-sensitive, and positive and negative sides must be matched).
I will get into more detail on wiring in the next steps. See the pictures here of my glow tubes:
Step 5: Wiring the LEDs
Use color coded wires so you don't lose track of positive (+) and negative (-) terminals. The negative terminal on an LED is the wire closest to the end on which the lip is flattened.
Use good-quality, weatherproof electrical tape to secure the wires to your bike. Black tape works great for me because my bike is nearly black.
When you get to the moving part - the handlebars - you will need to make a loop of wire across the moving area so the handlebars can be moved freely.
Make sure all the wires from different lights come together into one main pair of wires, which will come up the stem and connect to the Altoids tin.
Step 6: Adding Other LEDs
Add LEDs anywhere else you like. I have a combination of glow sticks and bare LEDs on my bike.
The axles in my wheels are a shiny, un-painted metal, so directing LEDs onto these makes them reflect the light in all directions.
I also added 2 blue LEDs under the bike to shine directly on the ground.
The red rear light is a store-bought bike light.
My spedometer also has a light so I can see how fast I'm going at night. The speedometer light is rigged on some stiff wire to allow for it to be bent into the right position.
Be creative, and light your bike however you prefer.
Step 7: Finished!
You're now finished lighting your bike!
Check your system to make sure all the lights are lighting up correctly.
Make sure that:
1) the polarity is always correct
2) there are no short circuits or exposed wire
3) everything is soldered in place for solid connections
4) all the LEDs MUST be wired parallel, not in a series (wiring in series decreases voltage to each LED)
Now, go get a cheap tail light fixture and a powerful headlight and you're set!
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