Emergency Led Lighting Made Ridiculously Simple (UPDATED 2-13-14)




About: Hello

Hurricane Isaac hit about a week ago and thousands of homes are still without power. Well, lighting is no problem.All you need is you car, a led dome light and some wire.


Step 1:

Here is a link where you can buy 12 volt LED car dome lights. This type (festoon, see link below) are typically non-polar meaning that it does not matter which way you connect them to 12 volts.


If you are going to connect one of these directly to a car battery you should connect long wires to the battery terminals first and then connect the wires to the light (several feet away from the battery to avoid a spark around the battery). The preferred method is to connect to 12 volts through the cigarette lighter socket. 

The cigarette lighter socket is typically fused and the battery is not, so if your emergency light has a short circuit your wires will melt / fry (not good) because the battery can supply hundreds of amps of current. That’s why it’s a good idea to make and test one before you need it. Better yet make one with a connector / cable with a built in fuse:



I got my dome light from here for a little less (the ones with the silver pointed ends are the non polar ones. the ones with red and black wires must be connected red +, black -):


You can probably get these from some auto parts stores too. These are quite bright and can easily provide enough light to read or play cards. Any kind of wire will work but telephone wire is probably the cheapest and you can usually get 100 foot rolls at hardware stores, radio shack, walmart (electronics / entertainment department). You should be able to run a led dome light for several days without running the battery down too far. You may want to start up the engine every day or every other day and let it idle for a couple of minutes. With a full tank of gas you should have lighting for many months.

Telephone wire:


All kinds of low voltage wire:


Speaker cable will work fine, so you may be able to get everything you need at a well stocked auto parts store.






Step 2:

Here is my prototype all wired up. In an emergency you can strip the wires, twist then together and then cover the connections with tape. I soldered and used shrink sleeve since I was planning ahead.

Step 3:

It works fine. It was cheap and easy.

So, are you ready for this:


Or this:



See all my instructables here:




Step 4: UPDATE: 2-13-14

Update 2-12-14:

I recently bid on several LED strips on Ebay. The auction I won was for a reel of 240 warm white leds “wired” in sets of 3 with resistors for running each set of 3 on 12 volts. The 240 leds make up 80 three led , 12 volt circuits. You can cut them to the lengths you want. So if you need a little bit of light you cut off one set of 3. If you need a lot of light you may want to cut off a foot or two of circuits. They can be powered from either end of the strip. There is 3M adhesive tape on the back. My winning bid was $4.50 for a 4 meter strip (shipping included). This is about half the cost of just buying it on Ebay. Each 3 led circuit cost me less than 6 cents each. To prep some circuits for emergency lighting I will solder a few inches of thin insulated black and red wire to several 3 led sets. 10 sets will cost under a dollar with the wire. In a long term power outage I would just need to cut and strip any of the following cheap wire: 4 wire telephone cable, landscape sprinkler cable or CAT 5 cable. Then strip the ends, twist wires together and insulate with electrical or duct tape.

The pictures for the update are:

Three LED circuit front view.

Three LED circuit back view which shows the 3M tape.

The whole reel is lit up slightly with a 9 volt battery.

Three LED circuit lit up with 12 volts.



One more thing. Last year I bought 20 festoon type LED dome lights, 6 LEDS per dome light for $12.00 (free shipping, 60 cents each per light) on Ebay.





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    4 Discussions


    BEST solution is if you can find someplace that sells ham radio gear, pick up some Anderson Powerpole connectors. Attach heavy (as appropriate for the battery) wires to the battery with an appropriately sized automotive fuse inline, terminated in Powerpoles. A 7Ah battery (8 or 9Ah are also 7Ah, just with more clever definition of "Ah" to make them seem bigger) retails for about $20-30. You'd be amazed how much light you get out of 3 watts of white LEDs, which Ohm's Law tells us is 0.25 amps, which probably means about 20 hours of light. (Yes, I'm factoring that you may want to use that battery again and that you don't want to drain it all the way to "dead".)

    Powerpoles aren't cheaper than cigarette lighter connectors, and you need a pin crimper to assemble them. But if you put them together in "ARES standard", they're cheap and basically bi-directional. They're genderless, which is really very handy. And they're smaller than cigarette lighter connectors.


    Reply 6 years ago on Introduction

    Here is one similar to the one I purchased about a year ago:


    The specifications from Deal Extreme says: 0.84 Watts (under 100 milliamps) 145 Lumens (for reference, a 40 watt incandescent is under 500 Lumens The most common wattages for this type of bulb appears to be 1 watt (or a little less) 2 watt and 2.5 watt. I have soldered up some 12 volt light boards. They are easy to make. The ones I make have 4 leds and a 33 ohm resistor in series which ends up being about 20 milliamps at 14 volts max. for about 1/3 watt.