DIY Emergency Lighting
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The Idea

So, I had the idea to make an emergency lighting system after the experience of having a blackout for a few days about two years ago. I finally had the resources to do it, but I also had two years to think about how it would be done. I thought Christmas lights would be good because I knew that they were wired in a parallel series kind of thing, so I could rewire it to run on something smaller than 120 volts. I also thought it would be good if it could run on a rechargeable battery like a car battery so that I could charge it up when there was power and in the apocalypse, maybe charge it up with a solar panel. Also, I used a broken chain of Christmas lights because I knew that no one would miss that chain. Also since this is for an apocalypse or bad event or something, the build can be done with scissors and electrical tape. Keep in mind that the lights used are traditional incandescent lights and not LED lights, in theory it is the same idea but I haven't looked into it.


The Engineering

So, I had to figure out the exact wiring for the lights while they were still unmodified. I knew that they had to be in series somehow because each one of those bulbs ran on 3 volts. So if it ran on 120 volts, then you divide 120 by 3 and you get 40 bulbs in series, but in this case there were 35 bulbs, so they got a little more juice but it does no harm. So 70 bulbs total and 35 in a series meant that there were 2 units of 35 bulbs wired in parallel. Then I figured out that if the battery outputs 24 volts, then 8 bulbs running at 3 volts would take 24 volts no problem. The problem now was that a lot of the bulbs were burnt out, hence the "broken chain of Christmas lights". So if I wanted a multiple of 8 with however many bulbs were left, then I could only have 48 bulbs or 6 units of 8 bulbs. However this is only for 24 volts, if you want 12 volts then you need units with only 4 lights each and for 6 volts it could only have 2 lights each. A schematic of the idea is given below. The yellow dots are the lights, the red lines are the small chains of sockets with the lights in them and the black things are the two main wires that supply power to the chains.


Construction

First cut off the plug.

Then remove the middle wire that doesn't have anything hooked onto it, as shown below.

Then cut the pieces to have 8 sockets each like so, have enough for each working light bulb.

Here I am testing to see if it really works and yes it does, 8 lights for 24 volts.

Now put all your working lights into the sockets for the little chains you made

Now to rewire it into one long strand. You should have gotten two long socketless wires from the beginning. Lay those out and connect your strings of lights by stripping just a little piece off and attaching your lights by twisting the wires and wrapping them in electrical tape. Continue that for all the lights throughout the whole length of the two wires, but you want some at the ends to connect to the battery. You want the chains connected to the two wires in the way like the schematic above, so that the two wires supply power to each chain.

Here are the lights after being wired and now tested. Notice how each end of each chain is connected to a different supply wire, this is just like in the schematic for parallel circuit lighting.

Now I finish the lights by attaching the original plug to it. It is VERY IMPORTANT to note that even though it has the plug, you should NOT plug it into the wall's power since the lights are now rated for 24 volts, not 120. Doing so may cause an electrical fire, kill your fuses, kill your lights, and worst of all kill you.

Now I am attaching the outlet plug to the battery, that is why I attached the male end onto the string of lights, so it could plug into the battery.

As you can see, it works, now I've got a source of light when the power is dead. Hopefully this information is helpful during times of electrical distress. Remeber, be safe and be careful because I am not liable for anything you do with this.