How to: Christmas Lights! 120v to 12v DIY

Well after Christmas I had an idea that I might be able to convert some of the 120v strings of lights that were on sell to work off 12v to decorate my car next year. Turns out it's very easy.

I found some instructions online but the site has now gone down so I decided to do a write up for those of you that might want to put some on your car foe the holiday season next year.


So to start you need to pick up some Christmas light and not just any kind. You need the ones that have a plug on both ends and have 3 wires running through them.

Here's the box of the ones I picked up they were about 1$ a box on sale.


Here are the tools I used to convert mine.

I also found my pocket knife very useful too.

Now take your lights out of the box and unravel them. Take a close look at the wires after the first bulb you will see 3 wires. One has all the bulbs and the other two act as an extension cord so you can connect other lights. Essentially what you are going to do is every 5th light bulb splice it into one of the wires without the bulbs alternating wires as you go.

Alright for you visual people here's some pics and more detailed explanation.

First thing to do is cut off the plug that goes into the wall. That will keep you from plugging the lights in and overpowering them.


Next thing I do is slip an object over the loose wire so that way I can easily keep track of which wire is which. For this one I use a piece of solder formed into a circle so I could just cut it at the end. I've also used a small key ring before too. Make sure to place it on the wire that isn't tied into the first bulb.


Now you're going to slide the ring through the wires and count the bulbs as you go. Once you pass the 5th bulb unravel the wires enough so you can identify the wires.


Now take the wire between the 5th and 6th bulb and the wire that has the ring on it and remove about a half inch of insulation from each wire.(I found this easiest by using the wire strippers and clamp down in one spot then move a 1/2" and repeat then I used the serrated portion of my knife to cut the insulation off. Bad explanation I know but it's the best I can explain.)


Now take the bare wires and twist them together and solder them.


Now wrap the splice with electrical tape. Then wrap all 3 wire to help keep them together.(Tip:cut your piece of tape 2x longer than you think you need and wrap the splice then add the third wire and continue wrapping. Saves time and tape.)


Now move the ring down 5 more bulbs.


And splice the wire between the 10th and 11th bulb and the wire WITHOUT the ring.


Now just do this 8 more times going 5 bulbs each time and remembering to alternate between the wires.

When you get to the end of the string cut off the other plug and make sure none of the wires are exposed.

That's pretty much it just put them on the car and wire them up.


Oh and a note on the first set I made the first 5 bulbs wouldn't light up. I changed the pattern on the set I showed above but I keep forgetting to test them. If I find any problems I'll post up and let ya'll know.

Bump since it's Christmas time.

Added Christmas light to the rig over Thanksgiving.

I've got all of about 3$ invested in this project. Only thing's I actually had to buy was the lights and I bought them on sale after last Christmas. The rest was leftover stuff from other projects.

I wired them up using a relay that I trigger by the ground wire instead of the positive like normal to help cut down on the length of wire and to simplify the wiring.

Well enough boring stuff here's the pics.




Here's where I installed the relay. The wiring isn't pretty but it functions and it'll only be there for a month anyways.


The switch is a rocker switch that I placed under the dash so it's out sight.

LOL.

I wonder how many lights you can run.
If you get LEDs that take very little power.. I can imagine wrapping the whole truck in it.