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As said before in another thread, this may be common sense to some members, where as other members are just being introduced into the world of automotive lighting. Just something I put together to solve a question I see every once in awhile.

Thanks.

You are installing 4 LEDs in your car. You have a ground and a power source. Do you need to run a wire from each LED to the power source and ground? Do you need to run 4 wires to your switch?

You've got a basic setup with just 1 LED. Run 1 wire from your power source to the positive lead on the LED, and another wire from the ground of the LED to the ground/chassis of the car.

Quite simple. Like this diagram:


Now, you want more than just 1 LED. You copy what you did with 1 LED, but apply it to 4 LEDs.

It looks something like this:


That's a lot of wires! And if you're installing the LEDs in the very back of your car, things get messy quite fast. Wouldn't it be better to run a SINGLE wire from your power source to the location of your LEDs? Once that wire is at the location you want, you can "tap into it", "split it off", "tee it off", etc... As long as the metal connects, an electrical connection is made, and you can pretend it is a single wire.
This is better! Especially if the LEDs are a long distance from your power source.


Suppose you have a water spigot on the side of your house. You've got a brand new lawn and 4 brand new gophers. You want to give each gopher its own "gopher drinking fountain". You get a 4-way garden hose Y splitter and 4 100 foot garden hoses. You run them 100 feet away to your lawn.
Lots of hose


Is this really the best way spend your saturday? Running 400 feet of garden hose? Instead you would probably get a single 100 foot hose, and a few 5 or 10 foot hoses like this!
Less hose. Happy gophers.


Electricity is the same way!

Remember: you always need to fuse your lights.

You can run a wire from the battery (and put a fuse as close as possible - maybe 12 inches). Run the wire into your car, split it off to a few switches, and split off some lights to the other ends of those switches.

Props to the guys at Oznium

 
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good post mang. +1 i like the gopher diagrams too. rofl

 
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good post. if you can help it (design wise), always wire as many leds together in series as possible off the same wire so that the leds--and not the resistor--use up the total voltage. if you are wiring amber led which needs 2v to work, and you have a 14v power supply, you can and should try to wire at least 6 leds together. just wiring one would mean theres still 12 more volts that is left for the resistor and it will get hot trying to dissipate so much heat. there is just so much info that i dont think these pics can explain anything. you have to know alot more than basic wiring to make them work right.

 
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sooooo, in diagrams 1 and 2 each light is receiveing 12 volts of power and in diagram 3 the power is being divided by the 4 lights makeing it 3 volts each??? Or do they all still receive 12 volts each?

 
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diagram 2 and 3 are exactly the same. Diagram 3 just uses less wires. The diagrams shown are wired in parallel, which means all the leds receive the same voltage. However, if it were wired in series, the voltage across every light would be different.

Edit: When wiring things such as leds and lights, it is not practical to wire them in parallel like the diagrams above. It would require a lot of cutting, splicing, and a lot of wires. It would be better to wire them in series like gearbox said.

 
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Remember, LEDs ALWAYS need a current limiting resistor(s) somewhere in the circuit.