12 volt wizards?

[macinyart]

Greetings,
I am looking for an automatic(doesn't need a toggle, works on its own) switch (I think) that will fit into a circuit that activates a light (12V) when the ignition is turned off, but deactivates the light when the ignition is turned on or alternatively the system is charging (the engine is running). The light is not currently installed. Does anyone of you 12 volt wizards have any ideas? Thanks.

[Cronoh]

I have something similar set up (Same idea) in my jeep. The way Tom did it was like this:

In the factory relay panel, there were a bunch of unused wires, such as.. Rear window heater which I don't have the luxury of :p It is still wired though. Tom spliced that wire to also send power to (wherever you need it to go). These only get power when the ignition is turned on. Now, use a 5 pin relay. Use the spliced wire as your "Switch" to tell the relay to turn on or not (Sorry, I don't know all the technical terms). Using the relay, you can power up your 12v "target" depending if the switch is on or not.

Sorry I feel really stupid posting this while I'm completely blanked on the technical terms for all of this stuff :/

[Fire Ball]

Easy instal. What is the aapplication.

Simple DPDT relay should work. The reason I ask the application is if it fails, what are you doing without :D

[DesertRat]

http://www.4x4s-pod.com/
Great setup and good service!

[AZLugz]

Took one of Stu's and modified it for what I think you are asking.

Problem is the light will be on any time the rig is not so it would drain the battery

Another way to do it tho, would be to have it where the light only comes on when the ignition is ON but the battery is only seeing 12V (not charging at 13+V), then you would see the light with the key on engine off or if the alternator failed. This could be assomplished with the addition of a diode and slight changes in the wires so that the relay only activates above 13Volts

http://www.virtualjeepclub.com/attachment.php?attachmentid=18619&d=1202750324

[macinyart]

Thanks guys, I need a source for the relay still. I agree with Bill, this should be easy, just don't know where to get the components. Checker, Radio Shack all met this request with "Duh". I will ask again with the right words.

[AZLugz]

both have them but checker is a little cheaper on the auto relays

[macinyart]

Fireball says a SPDT relay should work. The light is scheduled to be a blinking LED, should take a while to drain the battery, but you are right, there is a constant current drain with it. I use a kill switch, so maybe I might hook it up so that when I activate the kill switch to turn off the fuel pump it would blink. Now we're getting serious? :aagh:

[Cronoh]

I have a blinking LED for when my killswitch is not turned off. Maybe this isn't smart, but mine blinks for over a week without harming the battery :p

Also, on one of stu's writeups there he has a link to a website called robot marketplace I think, they sell relays with the wires "hardwired", so its not a relay that plugs in. I bought 6 of these from them, and they work freaking great! And way cheaper than stores, took about 3 days to get here.

I think they were 3$ each. 3$ for the 40amp relay, and 3$ for the plug that goes into it, with the wires already coming out the bottom, ready to be soldered (or however you want to run the wires).

[Cave Gimp]

What you are looking for is a relay that is normally closed, meaning no power, it closes giving power to the LED. An SPDT will work, but you will have to figure out what the extra side (the one without the LED) will be doing, or just leave it disconnected. You are likely to have better luck finding a SPDT than a normally closed SPST relay. Here is a link to the site Cronoh said Stu mentioned. http://www.robotmarketplace.com/products/0-RELAY40.html

[AZLugz]

I showed it with the one I did because that is what you will find in the auto shops like checker and it was said to keep it simple, with the drawing I did, the terminal for circuit engaged is left open. This can be used for anything you want to power when the key is on tho. Can't get much easier than that

[Markos]

Fireball says a SPDT relay should work. The light is scheduled to be a blinking LED, should take a while to drain the battery, but you are right, there is a constant current drain with it. I use a kill switch, so maybe I might hook it up so that when I activate the kill switch to turn off the fuel pump it would blink. Now we're getting serious? :aagh:

The radio on my Jetta blinks with the ignition off. It would take a really really long time to drain the battery. I'm guessing months...

[fatboypup]

I had a blue led thing on my jeep dash that kinda scrolled like night rider I got it at pepboys you give it constant power and run the ground to a swiched power ...... so when its on its not getting ground so its not lit and when the vechile is off the light gets ground and it comes on ....... easy to do right from the fuse box in the jeep

it was one of these http://www.varad.com/v4/products/scanners.php

[dobslob]

Fatboypup is right.

This is really easy. We used to do this at several car audio shops I worked at. All you need to do is hook the LED straight to the ignition harness. Use constant 12 volts as power and ignition as ground. As soon as ignition is shut off it goes to ground at completes the circuit. No extra parts necessary. And it will be fine for months, but you better not let a Jeep sit that long, there is too much to do.