Lightweight LED Bottle Lights

Lightweight camping doesn't have to be boring and without style. This Instructable helps you to make your own 7 gram glamping lights to set a party atmosphere around your camping spot. All you need are some basic tools you find around the house, some electrical tape, colourful LEDs, coin cell batteries and a few minutes of time. You can build the lights for less then €0.50 each, almost for free and hang dozens of them around your tent when camping. Who said you need to spend a lot of money to make your camp site glamorous?

This project was inspired by the concepts behind LED-throwies, the DIY camping light with a jug of water and a head torch, the LuminAID light of Tentsile and tries to recreate my own childhood memories of garden parties which where lighted with these colourful light bulbs. In that process I tried to connect sustainability (reuse of plastic bottles) with the specific needs of camping outdoors (lightweight items).

A dream, making camping more magical: I want to hang a lot of these bottles in the top of trees while camping and enjoy the wonderful colours around my tent. I ordered 20 more batteries and LEDs and looking forward to it. If you like this project, please send me pictures of other camp sites with these lights, and let us show together that camping is magical!

For this project you will need the following:

• LED lights in different colours. The blue and green ones diffuse better due to their shorter wave length and thus give nicer results when you have clear bottles. (you can buy LEDs on ebay for less then €0.01 a piece if you order in bulk).
• a pack of coin cell batteries (you can order these from ebay for less then € 0.14 each, including shipping). I used 3 Volt CR2032 Lithium batteries, which last a long time.
• some cardboard
• 2 paperclips for each light
• some electrical tape
• some nylon cord (or anything other to hang your lights up into the trees)
• a small bottle of water for each light. You only need the bottle cap to make the light, when camping you can screw the bottle cap to other bottles as well.

Tools needed for this project are:

• a safety pin (preferably the same thickness as the legs of the LED light)
• a waxine light and something to light it
• a cutting knife
• a pencil

Additional tools that can make it a bit better, but are not obliged:

• plyers if you want to make beautifull bends, but some pressure from your finger tips works just as fine.
• a soldering iron and some solder
• a glue gun

1. Light the waxine light.
2. Trace the bottle cap on a piece of carboard and cut out the circle. This will be the positioned on the cathode side of the battery.
   
   about the LED lights:
   The long lead is positive (+). It is called the anode. The shorter lead is negative (-). It is called the cathode.
   
   
3. Place your LED in the middle of the cardboard circle and mark where the two legs should go.
4. Punch a hole through one of these marks and transfer that hole to the bottle cap (a light push with the needle should suffice).
5. Rotate the negative cardboard 180° and make another mark on the bottle cap.
6. Heat up the tip of the safety pin above the waxine light and use it to push through the two markings at the top of the bottle cap.

1. Push the LED through the bottle cap from the inside out.
   Optional: add a dash of hot glue in between the LED head and the bottle cap right before pushing the LED the last few mm. This way your bottle cap is sealed and the light can perform also on windy days when you are swinging in the trees.
2. Fold the positive anode of the LED horizontal (the positive anode is the longer one)
3. Unfold the paper clip and attach it with some electrical tape to the positive anode to make it longer. A bit of soldering would increase the performance if you have the tools.
4. Add the negative cardboard circle by pushing the negative cathode through the hole.
5. Fold the negative cathode on this cardboard. Try to increase the contact surface area so that the coin cell battery can lay horizontal on it.
6. Wrap some more electrical tape around the paper-clip, leaving only the last 1 cm bare metal.
7. Fold the paper-clip upwards and then downwards again, making a little spring that can push on the coin cell and that holds it in place.
8. Take four short pieces of electrical tape and tape the coin cell in place, leaving a small square of the positive side reachable for the paper clip.
9. Put a small piece of cardboard in between the paper-clip end and the battery to break the circuit.

This is the moment to test out your circuit and the switch mechanism. Put the positive signed cardboard in between breaking the circuit. Remove it again and check if the paper-clip makes contact again and that the LED glows brightly.

Adjusting the circuit for optimal LED performance

You can boost the performance of your lights by linking a resistor in series to the LED to optimises the voltage and current going through the LED. Each colour LED needs a specific voltage and current to perform optimal. I included a table with my calculations for each colour LED. I try to go for the maximal allowed voltage to get the optimal luminous intensity for each LED. Most LEDs need a 30 Ohm resistor, only yellow ones need a 43 Ohm resistor. The resistance in the paper clip will let the voltage drop even a little bit lower when going through the LED.

1. Add some electrical tape around the bottle cap to hide all cardboard and electrical components
2. Reheat the tip of the safety pin and punch two holes in the top of the cap, next to the coin cell. Avoid the sides where the positive anode of the led light is located
3. Fold the second paper-clip and push it through the two holes, making a hook.
4. Attach some nylon cord to the hook and hang it in the garden.
5. Finally, take a second small piece of cardboard, wrap it in electrical tape and use it to break the circuit. Remove it when you want to turn on the lights.

The final product was somewhat like I expected it to be. We currently use it to create a nice mood in our garden when we want to sit outside and I see myself taking a few of them with us next time we go camping, weighing only 7 gram for each cap. Since we always have some bottles around (maybe even with coloured drinks in them), we can always change the caps with these glamping lights.

what will I do differently next time: Well, not much. It appears that the blue and green LEDs give more light compared to the warmer colours. So I would throw in a bit more of these if I make a batch or add two LEDs in parallel in a bottle cap when using red or yellow. Also, I would need a better camera and work setup to make better pictures for Instructables :-)

On safety:

Like don't drink and drive, water and electricity are a recipe for disaster. Unlinke drinking and driving, the disaster can be limited or eliminated if one behaves carefully:

• I tried to cover all parts as much as possible with electrical tape, limiting the chances for short circuiting.
• The caps shouldn't be used to close bottles when transporting. If executed properly, nor the anode or cathode are accessible from the inside of the cap. However the two feed through holes and the holes for the holding mechanism aren't watertight.

This Instructable makes use of sharp objects, heat, electricity and small parts, think about the safety of you and your children when attempting to make it and enjoy!