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Thread: Wiring power from Ignition Switch

  1. #1
    Low Bitrate briderx's Avatar
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    Wiring power from Ignition Switch

    I have my power supply ran to my ignition switch, instead of directly to the battery. My thinking was this: You get the same CONSISTANT voltages through your ignition switch, as you do running wire straight to your battery. The only thing you'll be saving this way, is 10-15 feet of extra wire. Possible problems: Maybe too much amperage on the ignition switch wiring..

    What's your ideas on this? I have been using this for over 4 months without a problem. I also have an inline fuse in place..

    Please state reason you agree or disagree.

  2. #2
    Neither darque nor pervert DarquePervert's Avatar
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    Well.....

    For one, any PSU that has an integrated SDC (or a non-integrated one, for that matter) will not work properly. Basically, when you turn off the ignition, the power is cut to the PSU, and the PC would do a hard ****down, which isn't a good idea.

    The proper way of wiring a SDC is to have a line running from the battery for constant 12v power and another running from an ignition switched source, as well as a ground line. The state of the ignition line triggers startup/shutdown.

    Amperage is not so much an issue as long as your wiring is good.

    You haven't given any details as to your setup, other than this tidbit of wiring information. It would help if you provided more details.
    Have you looked in the FAQ yet?
    How about the Wiki?



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  3. #3
    Low Bitrate briderx's Avatar
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    Sorry.. At work, and shouldn't have been on here while working..

    So.. Here's my deal. I'm running the Opus 120w power supply. It does the 10 second delay for startup, and when ignition is turned off, the computer shuts off after 10 seconds. So, that shouldn't be an issue, as there is no hard offs.

    I don't know what "SDC" means.. So, I can't answer that. What other information can I offer?

  4. #4
    Variable Bitrate billmee's Avatar
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    First off I disagree with using the starter switch for anything other than starting your car.
    That is what it was designed to do. Replacing a starter switch is a royal pain in the azz and drawing more current across the switch contacts is one of the few ways to shorten it's life.

    Your car manufacturer already provides a signal to turn on accessories it is referred to as IGN and ACC. Use it to start the OPUS, you already paid for this feature.

    I do support your reluctance to wiring direct to the battery. In my opinion a 14 gauge wire to a cig lighter is sufficient to power most pc's listed on this forum.

    DP's tla SDC is a shut down controller.

    ( tla is a three letter acronym for three letter acronym )

  5. #5
    Fusion Brain Creator 2k1Toaster's Avatar
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    Quote Originally Posted by briderx View Post
    It does the 10 second delay for startup, and when ignition is turned off, the computer shuts off after 10 seconds. So, that shouldn't be an issue, as there is no hard offs.
    How did you manage that wiring miracle? The whole point of the ignition wire is to only be live when the car is on. If you are somehoe pulling power when off, then that sounds no good. Unless this is one of those stupid wires that stays on until the door is opened or something. But for what you suggest, you need a wire that is live longer on the power line, then on the ignition line.
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  6. #6
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    Quote Originally Posted by billmee View Post
    First off I disagree with using the starter switch for anything other than starting your car.
    That is what it was designed to do. Replacing a starter switch is a royal pain in the azz and drawing more current across the switch contacts is one of the few ways to shorten it's life.

    Your car manufacturer already provides a signal to turn on accessories it is referred to as IGN and ACC. Use it to start the OPUS, you already paid for this feature.

    I do support your reluctance to wiring direct to the battery. In my opinion a 14 gauge wire to a cig lighter is sufficient to power most pc's listed on this forum.

    DP's tla SDC is a shut down controller.

    http://img337.imageshack.us/img337/2319/class010dh1.jpg

    ( tla is a three letter acronym for three letter acronym )
    You don't have to use an actuall ACC or IGN line. the more easier way is this....

    since you already have to run a constant 12V line from battery through firewall into cabin, it's easier to tap a mini-fuse with a fuse tap anything that comes on when the car is on, and is off when car is off. (use a voltemeter to check)

    the SDC does not know the difference between a acc line, ign line, or what i did.

    I do this because it's easier to run the wiring together through the firewall, and tucked under console carpet to pc under my seat.

    the grounding is what you can do in the cabin...

    it makes absolutely no sense to me to go hunting under your dash for an acc or ign line when i easlily just tapped a line under hood.

  7. #7
    Neither darque nor pervert DarquePervert's Avatar
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    Quote Originally Posted by DarquePervert View Post
    Basically, when you turn off the ignition, the power is cut to the PSU, and the PC would do a hard ****down, which isn't a good idea.
    That's supposed to be shutdown.
    Quote Originally Posted by briderx View Post
    Sorry.. At work, and shouldn't have been on here while working..
    tsk, tsk, tsk.
    don't feel bad. I do the same thing, amigo.
    So.. Here's my deal. I'm running the Opus 120w power supply. It does the 10 second delay for startup, and when ignition is turned off, the computer shuts off after 10 seconds. So, that shouldn't be an issue, as there is no hard offs.

    I don't know what "SDC" means.. So, I can't answer that. What other information can I offer?
    Opus power supplies have an integrated SDC (or shutdown controller). Sorry for the confusion.

    The Opus should have three lines going to it:

    A constant 12v, straight from the battery's (+) terminal (with a fuse within 18inches of the battery). This goes intoe the PWR or +12v line of the Opus.

    A ground, straight to the battery's (-) terminal or a bare metal bold on the chassis. The latter is preferred. This goes to the GND line of the Opus.

    A switched line from an ignition-controlled power source in the vehicle such as a cigarette lighter or the stock radio harness.

    If this is not how you have your Opus wired up, the only way I could see it working is if both power lines were switched. Basically, both lines would be hot when you turn the key, and the Opus would trigger startup. The downside is that when you turn the key off, the system loses power and you get a hard shutoff, which could screw up your Windoze.
    Have you looked in the FAQ yet?
    How about the Wiki?



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  8. #8
    Low Bitrate briderx's Avatar
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    Quote Originally Posted by DarquePervert View Post
    That's supposed to be shutdown.

    tsk, tsk, tsk.
    don't feel bad. I do the same thing, amigo.

    Opus power supplies have an integrated SDC (or shutdown controller). Sorry for the confusion.

    The Opus should have three lines going to it:

    A constant 12v, straight from the battery's (+) terminal (with a fuse within 18inches of the battery). This goes intoe the PWR or +12v line of the Opus.

    A ground, straight to the battery's (-) terminal or a bare metal bold on the chassis. The latter is preferred. This goes to the GND line of the Opus.

    A switched line from an ignition-controlled power source in the vehicle such as a cigarette lighter or the stock radio harness.

    If this is not how you have your Opus wired up, the only way I could see it working is if both power lines were switched. Basically, both lines would be hot when you turn the key, and the Opus would trigger startup. The downside is that when you turn the key off, the system loses power and you get a hard shutoff, which could screw up your Windoze.
    Maybe I'll take a picture of my setup when I get home.. I'm actually getting confused as to how I have it wired ha ha.. Anyways, besides the point, which we should probably skip, is that the system powers up like it should (after 10 seconds) and then it'll stay on, whether the engine is running or if I just have the accessory on. If I shut the ignition off, after about 10 seconds, the computer goes into it's shutdown mode (just as if you were to go to start>shutdown.. It works perfect.. My big concern is burning the car up.. Starting it on fire.. Or even just killing my ignition switch. I'll wait till I get home.

  9. #9
    Newbie Dingo509's Avatar
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    Ok what he's done (I think) is to run the wire that SHOULD go to the battery to the main power wire going TO the switch, this wire is hot at all times. Then after the switch he has the accessory wire for the opus tied in. that's the reason the SDC is operating correctly.

    So basically he's running the computer on a wire that was meant to feed the ignition switch only. That's where the problem is. That wire was meant to carry the amperage for the switch functions only, NOT the additional 10-12 amp that the Opus can pull.

    It's easy to do the wrong wiring in his vehicle, I know, I have one too. There is a 10?-12? gauge red wire that goes to the ignition switch that is hot all the time. It sticks out like a sore thumb and is easy to get to, so i does make for a temping place to hook to. But it's not correct.

    So briderx what you need to do is to sacrifice the time and run another wire directly to the battery. If it was me i would run a rather large, say 8 gauge Fused wire from the battery through a Fused distribution block in the dash or center console. then run your computer and other internal High draw electronics off that block. If your running a amp you may want to up this cable size up as high as 4 and even higher for multiple amps. I have relocated my batteries to the back and i run a 2/0 cable to a junction block under the hood and then have a smaller distribution block that runs my accessories. hope that makes since.

    Dingo
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  10. #10
    Low Bitrate briderx's Avatar
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    Quote Originally Posted by Dingo509 View Post
    Ok what he's done (I think) is to run the wire that SHOULD go to the battery to the main power wire going TO the switch, this wire is hot at all times. Then after the switch he has the accessory wire for the opus tied in. that's the reason the SDC is operating correctly.

    So basically he's running the computer on a wire that was meant to feed the ignition switch only. That's where the problem is. That wire was meant to carry the amperage for the switch functions only, NOT the additional 10-12 amp that the Opus can pull.

    It's easy to do the wrong wiring in his vehicle, I know, I have one too. There is a 10?-12? gauge red wire that goes to the ignition switch that is hot all the time. It sticks out like a sore thumb and is easy to get to, so i does make for a temping place to hook to. But it's not correct.

    So briderx what you need to do is to sacrifice the time and run another wire directly to the battery. If it was me i would run a rather large, say 8 gauge Fused wire from the battery through a Fused distribution block in the dash or center console. then run your computer and other internal High draw electronics off that block. If your running a amp you may want to up this cable size up as high as 4 and even higher for multiple amps. I have relocated my batteries to the back and i run a 2/0 cable to a junction block under the hood and then have a smaller distribution block that runs my accessories. hope that makes since.

    Dingo
    *Sense..

    Ha ha.. yeah it does. And you are 100% correct in how it's wired.

    One question I have though: Where is the power from the original deck coming from? It's not directly off the battery is it? From what I've seen (haven't been able to track it TOO far) but it seems it goes to the same line that the ignition switch is.. Am I wrong?

    I know this sounds like a tedious thread, but I just have issues running everything directly to the battery. The shorter the cable is, the more clean power that's going to the system, is my theory. And I am trying to exhaust EVERY POSSIBLE ALTERNATIVE. I have searched this post through and through and can't seem to find anyone else that's actually thought of that idea, or even tried it. I've searched google to see if I could find anyone that mentions doing it or not.. So, maybe this thread will help someone in the future that's thinking of doing the same thing.

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