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Thread: A question (or two) about wiring

  1. #1
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    A question (or two) about wiring

    I'm quite the computer nerd, but when it comes to car audio, I'm definatly a "noob" =)

    I've recently found out why a fuse needs to be as close to the battery, which I'm going to put in tonight. But I have a question. Both my power pc and cooling dc-dc power supply and the inverter have a max amperage of 30A. I'm running a 12 awg wire from the battery to the car. Now I assume that this won't be sufficient to run both at the same time, and I'm going to use a 0n-off-on toggle so that I can't. Will the 12 guage wire be sufficient for it? or should I try for 10?

    Also, about the switch. In the book for the inverter, it told me to run a 30A fuse inline with the battery and a 25A switch. Why the lower amperage for the switch? And would I be able to use a 20A switch or is that asking for a failure?

    I've just found this forum as I just got a car though I've wanted to put a computer in one for about 4 years now. But this is definitely a good source of info. Thanx.
    Thartek

  2. #2
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    use a relay on your switch. a 20 amp switch is big and clunky, but with a relay, you can wire up as small of a switch you can find. (down to ~200mA)

    you can get this at radio shack. it can handle up to 30 Amps.

    They come with instructions on the back, and are easy to wire.

    MIKE!

  3. #3
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    I've been tempted to try using relays. I get the gist of how they work (thanks to howstuffworks.com =) but I'm a bit curious about how I'm supposed to power the secondary switching circuit. I can't run it directly from the main power line due to the fact it'll have upwards of 30A through it, and I can't run it off the computer power supply as that is what I'm turning on and off. Should I find a 12v line going to the stereo and splie it, or is there a better way? (but I do like the idea of a relay)
    Thartek

  4. #4
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    How exactly were you planning to wire in the switch before? A relay can be wired in exactly the same way, the only difference is that is contains a coil for switching it on and off. The best way if possible would be to wire it directly to the battery. It would be a good idea to get hold of a dual battery terminator to get two outputs from each terminal. That's probbably the best way to do it. Wire the output to your fuse the then the relay. Also your inverter may recommend a 30A fuse although that doesn't mean it takes that much current. It's probbably the closest match. As a rough guide for each 10w you draw from the 230v side the inverter will draw 1A from the car battery. Hope this helps.
    Best regards,
    Matthew

  5. #5
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    Let's see... The way I originally planned to wire it was to go from the battery->30a inline fuse->25A on-off-on switch and then branch off in two directions to the p/s and the inverter so they couldn't both be on at the same time.

    I just went out (on my lunch break...heh =) and bought 2 relays, a 20A on-off-on switch and the inline fuse. so Now I'm going to run the battery to the fuse to both of the relays, and then the switch to the coils of each so I can still only switch one on at a time. My question was where can I get the 12v for the coils then. Or did you answer that with the "dual battery terminator" of which I know nothing about...

    EDIT: ok, that sounded wicked sarcastic and I didn't mean it that way. I just have no idea what one of those things are =)
    Thartek

  6. #6
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    Oh i see. I guess you could take that supply from just about anywhere. Like you said splicing the wires to the stereo should be fine. As mentioned before the relays are very low current so a high current supply isn't important.
    Best regards,
    Matthew

  7. #7
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    Ok, that shouldn't be too hard. I can do that =)

    And I think I hinted to this, maybe not flat out asked, but is the 12 guage wire I've got capable of taking the 30A load (before the fuse is blown)?

    And thanks electronicsuk. By the way, in your name, are you saying that electronics suck, or that you're into electronics and from the UK? =)
    Thartek

  8. #8
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    I think you want 10 gauge wire. If i remember correctly 12 gauge is only rated at 20A. As for the name, it's a bit of both. Yes I am into electronics and from the uk, and when something electronic decides not to work it can suck. It works both ways
    Best regards,
    Matthew

  9. #9
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    Lol, yeah, I'm the same way...just not from the UK... =)

    I'll go grab some 10 ga though and a ring connector for the battery this time... (stupid threading on bare wire to those stupid connectors!...)

    Thanks for your help
    Thartek

  10. #10
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    here a very good site for you to read up on relays and auto electronics: http://www.eatel.net/~amptech/elecdisc/relays.htm

    I agree with Electronicsuk, you sould get a lower guage wire. go to wall mart and pick up an amp wireing kit with 10guage or better... and use all the fuse holders

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