12V source when car is running?

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I have a green Buick Regal. The one from my sig. So my lighting theme is based around green.

I have all the interior lights replaced with LED, and most external lights except headlights and fog lamps.

For the foot pedal wells (what is this actually called?), I have green lights that turn on when the doors are open.

What I'm wanting to do is add lights that stay on the whole time the car is running while I drive. These will light the floor of the front AND back, and will either be green, or if green is too bright for night driving, I'll use RED. Something to give the floor a soft glow while I drive at night.


So basically, I need a 12v power source that is active when the car is running, or perhaps when the headlights are on, since this won't be as visible during the day, anyway.

 

[buck91]

Have you checked the wiring diagams? And/or use one of those add-a-circuits which plugs into the fuse box.

 

[exranger06]

The wiring harness at the stereo has a wire that's on only when the ignition is on or in the accessory position.

It also has a wire that's connected to the illumination circuit, so it will only be on when the instrument cluster lights up, and it's hooked up to the dimmer, so you could dim the LEDs along with the cluster.

It's very easy to tap into these circuits, especially if you have an aftermarket stereo already installed.

 

[Donald]

Why?

 

[razel]

I've been using the PCB LED from a 12V DC red LED bar for PCs as a rear center brake light replacement for over two years. Have no issues at all with the engine running at 14.4V.

Yes, it's only on when my foot is on the brake pedal. I assume you'll be fine as well. At worst your green LEDs will burn out right away, if you're lucky, the LEDs will just burn out faster. The good news is converting 14.4v to 12v is trivial. Many cell phone car chargers from a decade ago are 12v and 12v is very common voltage used in computers. Good LEDs also don't pull much amps so I wouldn't be surprised if a good cell phone charger provides plenty of amps. I'm sure you'll be able to find a 12v DC voltage regulator from 12v LED suppliers. Here's one from ebay:

http://www.ebay.com/itm//361260307714

You can find FAR simplier ones for your needs I'm sure.

 

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Originally Posted By: exranger06
The wiring harness at the stereo has a wire that's on only when the ignition is on or in the accessory position.

It also has a wire that's connected to the illumination circuit, so it will only be on when the instrument cluster lights up, and it's hooked up to the dimmer, so you could dim the LEDs along with the cluster.

It's very easy to tap into these circuits, especially if you have an aftermarket stereo already installed.


Whoa, nice!

Happen to know what kind of dimming signal is provided? I'm thinking PWM, which would be great for LED's.

Also, I wonder what the power amount is. Like if I could power the LED's off of it, or if I would hook it to an FET and have it control an existing power source.

 

[HerrStig]

System voltage in a 12 volt vehicle drifts from 12 volts when the engine is off to 14.2 or so when the alternator is running and the load is low. I'd wire up the circuit and insert a decade box (switchable resistors) in series -- apply 14 volts and work your way down in resistance until you see two volts across the box. Then there are 12 volts left to power the leds. LEDs are pretty forgiving about a volt ot two. ACtive regulators need "headroom" to work, a 12 volt output regulator needs about 15 volts to provide 12. If you used 6 volt LEDS you could easily operate a 6 volt regulator on a 12 volt input with plenty of headroom.

 

[CHARLIEBRONSON21]

Wiper circuit. Radio circuit. Anything that's on when the ignition is. Cigarette lighter.

 

[OpenClose]

Originally Posted By: HerrStig
I'd wire up the circuit and insert a decade box (switchable resistors) in series -- apply 14 volts and work your way down in resistance until you see two volts across the box. Then there are 12 volts left to power the leds. LEDs are pretty forgiving about a volt ot two.


I might actually apply 12 volts to 1 bulb, measure the current, and use that for the calculation, but yeah, same premise.

However, I am remembering the fact that I have leftover load resistors for the LED turn signal lights. If those are the proper resistance or higher, they would be great for this purpose. It doesn't need to be too bright, so I can overshoot.

 

[Nick1994]

Buy a 12V connector for the cigarette lighter and wire them to it and plug it in when you want them on. It's also already fused.

Don't forget the ricer wing

 

[OpenClose]

Do you guys know where I can find out what wire this is? The wiring diagrams in my haynes manual didn't seem to offer much.

I actually tried tapping from my headlights. The problem is that ground switches, not the +12v wires.

I remember seeing something about an orange wire on the ignition harness. But I don't remember where I saw that, or if it is a small signal or actual power.

 

[Klutch9]

It really depends on the vehicle. Your best bet may be to tap into the fuel pump circuit, cigarette lighter circuit, etc; finding the fuse for these should be easy enough. However, don't pull power directly from it. Use the voltage from this circuit to trip a relay that pulls power directly from the battery (or another constant 12v source). That way you won't overload any existing circuit. Relays draw hardly any current, so those can be used without issue.

 

[xxch4osxx]

Originally Posted By: Nick1994
Buy a 12V connector for the cigarette lighter and wire them to it and plug it in when you want them on. It's also already fused.

Don't forget the ricer wing

LOL That is just wrong with that wing!