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Thread: Will this work - Laptop install

  1. #11
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    Oct 2004
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    this is a bit of a hijack.. but im in the same boat, i need to power screen (8w built in regulator i guess cause it came with cig adapter), laptop (about 80w?, 19v 4.22A), and dvd drive (5v, 2A)...

    1. which if these should go to the hidden cigarette plug for power, i can get dc-dc adapters for both the laptop and dvd drive, the screen already has one.

    2. can they all go on a 3 cigarette adapter? the kind of splitter that makes 1 into 3?

    3. should they have ac adapters, and i get the best inverter i can find and connect them to that?

    4. i have no more head unit, the wiring harness is still in the dash though, could i tap into the former power wire of the headunit?

    5. my old head unit had a "turn on by ACC" function, could i use that wire to send a power on signal like say through that one turn on module i see here

    thanks for any help

  2. #12
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    You got what you need

    I wired a separate fuse box for my IBM R51 in a docking station, monitor, and amplifier. I have never had power issues with my computer, nor had my car battery die from this installation. Nor a fire (keeping fingers crossed). I did not need all the fancy setup offered with a shutdown controller, as I wired a switch from my dash to the docking station.

    1. Run a heavy gauge wire from your battery to the new fuse box. Make sure to place an inline fuse as close to the battery as possible. Remember that the fuse rating is related to the thickness of the wire and not the draw from the system. Too much current for a wire may cause it to melt and poof! your car may catch fire.

    2. You can now individually fuse each component with the proper sized fuse for the wires to them. I just cut the lighter end off a 120W car adaptor and wired the power for the computer into one fuse slot, the amp into another, the screen into another, and a five volt USB adaptor with spliced USB cable into the correct jack for my soundcard and USB hub, which in turn powers the GPS, mouse, etc. I have never had any power issues.

    3. The power to the fuse box can be switched on and off with a relay that is wired to the ignition. That way when the car is off, the power to everything is off, which is how I want it. For some reason, the GPS on the USB hub stays powered from the laptop battery, but in sleep mode, it drains so little, that it very, very, very slowly drains the laptop battery, but not the car battery, as the relay isolates the circuit.

    4. Make sure that all your connections are good and solid. Soldered is better than crimped if possible. Also, to reduce any interference, it is a good idea to try to ground everything to the same location with as short a run as possible. The grounds should be equal gauge wire as the power wires. And make sure the ground is clean and solid to a large piece of the car, i.e. frame of well attached body member.

  3. #13
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    Oct 2004
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    holy smokes this is exactly what i needed, thank you.

    i was wonering, by cutting off the cig adapters, you now run the wires to a new fuse box? or the cars fuse box, or just another inline fuse

    are there fuse boxes where you can attach the power and ground to, and then have a master ground wire go to bare metal, or do i have to split black and red and run all the blacks to the same spot.

    i think i want to... attach my availabe cig plug to my monitor, which only has a cig adapter anyways and draws only 8 watts... attach my slot dvd (5v, 2A) to the former power wire of my head unit... and run just 1 new power wire (with inline fuse) from battery to the auto/air adaptor for my laptop... hows that?

    my screen turns on and off by video signal, and the usb drive should power down when the computer hibernates, i would set hibernate to 1 min or the minimum.

  4. #14
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    Sounds like you got it

    Mengela

    My PC (with all the attachments) and stereo amplifier are mounted in my trunk. I purchased another fuse box at an auto supply store and mounted it on the side wall of the trunk. I wired the input of this fuse box with a heavy gauge wire directly to the battery, with an inline fuse as close to the battery as possible, and ran it along the left side of my car, under the carpet and trim.

    Remember that the fuse rating has nothing to do with the power draw on the circuit, but everything to do with the wire gauge. If you over fuse a wire, it has the potential to melt the insulation and cause a fire ().

    I opted to ground each powered tem to the same location to reduce any ground loop interference and noise. You will want to use the same diameter wire for ground as for power and make sure the ground wire is as short as possible and well grounded, or you WILL have noise in your system.

    For your monitor, you can keep the cig lighter plug it comes with and connect it to an add-on cig lighter receptacle (available at auto parts stores). If possible, wire this receptacle into a available fuse under the dash or the power line from your stereo. Note that the touch screen of your monitor will be connected to your system with a USB cable and this can be a source of ground loop noise. I used a high quality USB cable and did not have a problem. I also taped the the monitor plug into the lighter receptacle with electrical tape to keep it from disconnecting.

    The DVD will not work attached to your head unit, as it takes 5v, and a car stereo line will put out anywhere from 8-9V at the low end, to spikes of over 15V when the alternator kicks on. That is, unless you want to fry your DVD. There are several threads on a separate 5V power source. I tapped into one of the lines on my air/auto adaptor and it provides 5V, so this is what I power my USB hub with. Depending on the power adapter, you may be able to purchase a splitter and have one provide 12V and the other 5V.

    I also used an automotive relay that switches the power to the fusebox and therefore the computer and amplifier off when the car's ignition is off. This completely separates the computer and stereo stuff from the battery - no possibility for a dead car battery from the carputer circuit .

    Good luck and if you still can't get it going, I will try to draw a circuit diagram.

  5. #15
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    ThefDog - you got a diagram of how you wired the relay?

  6. #16
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    Here's a simple diagram for you

    Take a look at the following link, it should help alot:

    http://www.rowand.net/Shop/Tech/AllAboutRelays.htm








    All automotive relays are wired similarly, and everyone that I have seen use this numbering code for the wiring. Think of a relay as an electrically controlled switch (which is exactly what it is), that allows a small current flow to control the flow of a high current through it.

    As the image shows, the main power from your battery (fused close as possible to the battery) will connect to #30 on the relay. Wire the line for the trigger (#86) to a source that is on when the car is on, such as your radio, lighter, axillary fuse, amp turn on line, power antenna line, etc. You can safely splice into this line, as it will not be carrying much current. Wire the ground to #85 (it does not have to ground to the same location as your audio equipment and carputer, but it can). The wire carrying power to your fusebox will connect to #87, the "normally open" connection.

    When the relay is energized (when the ignition is turned on) with the current from whichever circuit you choose, it will close the relay, allowing a higher voltage current to flow to the fusebox.

    This type of power controller works very well with a laptop, as you can turn the car off and the laptop can continue its shutdown procedure on its own battery power. No waiting for the computer to finish shutting down or hibernating before turning the car off and getting out.

    Let me know if you need more help

  7. #17
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    Here's a simple diagram for you

    Take a look at the following link, it should help and is the source of the diagram below:

    http://www.rowand.net/Shop/Tech/AllAboutRelays.htm




    All automotive relays are wired similarly, and everyone that I have seen use this numbering code for the wiring. Think of a relay as an electrically controlled switch (which is exactly what it is), that allows a small current flow to control the flow of a high current through it.

    As the image shows, the main power from your battery (fused close as possible to the battery) will connect to #30 on the relay. Wire the line for the trigger (#86) to a source that is on when the car is on, such as your radio, lighter, axillary fuse, amp turn on line, power antenna line, etc. You can safely splice into this line, as it will not be carrying much current. Wire the ground to #85 (it does not have to ground to the same location as your audio equipment and carputer, but it can). The wire carrying power to your fusebox will connect to #87, the "normally open" connection.

    When the relay is energized (when the ignition is turned on) with the current from whichever circuit you choose, it will close the relay, allowing a higher voltage current to flow to the fusebox.

    This type of power controller works very well with a laptop, as you can turn the car off and the laptop can continue its shutdown procedure on its own battery power. No waiting for the computer to finish shutting down or hibernating before turning the car off and getting out.

    Let me know if you need more help

  8. #18
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    Make sure to connect to normally open circuit

    I forgot to stress that you need to ensure that you wire it to the normally open circuit. If you wire it to the normally closed circuit, when the car is off, it will be powering your fusebox = dead car battery.



    Cheers and good luck

  9. #19
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    Jan 2008
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    13
    thanks Thefdog, that was what I was looking for..newbies guide to wiring a relay for power purposes.

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