Using arduino for car rear light

Hi I am not very experienced in arduino or programming or electronic circuits although I am an electrition anyway my car has no aftermarket options for rear lights the lights themselves are only 10-15mm deep then the lamps are moulded into a casing on the rear so I was thinking about wiring some ws2812 digital leds into the lights to take over all functions

My first issue is utilising the 12-14v input from the car to power the arduino
Next is using the inputs for reverse,brake,indicator and side lights to wire into the arduino also 12-14v
And finally the leds are 5v so I need to make sure I have a supply for them capable of supplying the right amount of power needed

I have looked into octocouplers for the ligh inputs they may help but would still need to drop 12v to 5v for the supply voltages for the arduino and leds

Sorry for the long post and thank in advance

The sole purpose of your rear lights is a safety device to warn others of your intentions and behaviour. "I am not very experienced in arduino or programming or electronic circuits" does not sound like a position to ensure those lights continue to function with absolute reliability.
I would choose some less safety critical projects to learn a bit more first. Event then, I would not meddle with car lights, no matter how cool you think it might be.

They would be show use for 95% of the time really but would still need the standard lighting arrangements for driving at the show

Lewissv:
They would be show use for 95% of the time really but would still need the standard lighting arrangements for driving at the show

Start with some normal LEDs and switches and see if you can learn to make them do what you want. Only once you have a prototype going do you even think about modifying the car. You've got a lot of learning to do before you start messing with the actual car.

I have a arduino starter kit and an arduino mega iv managed to get sequential leds through the arduino and also how to dim them with a variable resistor my main concern going forward is dropping the 12-14v to 5v but also be able to run maybe 40w worth of leds I know it's a big step but I'm just trying to order some parts so I can do testing ect with a 12v power source for when I fit it and do testing on the car
Cheers

my main concern going forward is dropping the 12-14v to 5v

That’s trivial. Get a voltage regulator.

Delta_G:
That's trivial. Get a voltage regulator.

Yh but what type will support that amount of power draw?

Lewissv:
Yh but what type will support that amount of power draw?

If you have to ask then you are woefully unqualified to be making modifications to a two thousand pound machine that moves at 100s of feet per second and can kill a human so easily as an automobile.

You look at your LEDs and you calculate the current you need and then you look at datasheets for regulators and find one that says it can handle that current. It isn’t magic. I bet at Mouser.com you can even put in the required current as part of the part search.

There is nothing wrong with asking questions no need to be up yourself about it!
everyone has to learn at some point I am doing an awful lot of research into this project this is just part of that research .
I'm not building the light next week I'm am getting all the available information I need before I start a project so could be months before I start and I'm sure changing the rear lights for a show won't cause the car to veer erratically or crash into someone and kill them

Lewissv:
There is nothing wrong with asking questions no need to be up yourself about it!

No need to be what? What does that mean? Nobody is upset, just pointing out that you are a bit underqualified to be working on something that is going to speed around on roads.

Lewissv:
everyone has to learn at some point I am doing an awful lot of research into this project this is just part of that research .

Yes, and while learning they generally don't mess with things that could get people killed.

Lewissv:
I'm sure changing the rear lights for a show won't cause the car to veer erratically or crash into someone and kill them

Are you driving to the show? What if you stop and your light doesn't light and the person behind doesn't know you put on the brakes. How are you going to tell me that can't cause an accident?

I'm not saying that folks can't work on their car lights. I'm only saying that the particular questions you are asking make it painfully obvious that you shouldn't until you have a bit more knowledge about how this stuff works.