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Thread: Power help for new laptop CarPC

  1. #1
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    Power help for new laptop CarPC

    I'm the proud owner of a new Acura TL w/ built in navigation. I installed an aftermarket video selector & put a switch on the dashboard to switch between factory nav and aux-video.

    So, next step is putting in the CarPC. It's a relatively simple install because I'm not doing any mods to the dash (except the selector switch) or putting in a screen. (yes, text is not readable on the factory screen, but any frontend software designed for TV viewing is fine)


    What I currently have
    ---------------------
    • A spare laptop (Dell Latitude D600) wating to go in, and ordered one of the laptop-auto-on modules found in the power supplies forum.
    • A universal auto/air/wall adaptor w/ a tip for my laptop (it's a Kensington 120W) that works through the cigarette lighter.



    My questions/problems are:
    --------------------------
    1. How to power the laptop.

    I really want to just use the cigarette lighter, but I've seen numerous cautions against doing so. However, I THINK I will be OK, since this is just a laptop & I don't have to power a screen?

    I would like to tap into the fuse block using a mini Add-a-Circuit found at AutoZone, and wire in a new Cigarette power outlet to the trunk, where I'll connect universal power adaptor to the laptop. This is to avoid tapping into any existing wires, which I know is a bad idea.

    2. Noise on my screen.

    I've tested my setup by connecting the laptop's video out to my screen & everything is great when the laptop is running on battery. However, when I power the laptop by plugging into the center console or dash power outlet, I get wavvy horizontal lines on my screen. I have no idea how to fix this.


    Please help a newbie!!!

  2. #2
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    Quote Originally Posted by jwaters View Post
    I'm the proud owner of a new Acura TL w/ built in navigation. I installed an aftermarket video selector & put a switch on the dashboard to switch between factory nav and aux-video.

    So, next step is putting in the CarPC. It's a relatively simple install because I'm not doing any mods to the dash (except the selector switch) or putting in a screen. (yes, text is not readable on the factory screen, but any frontend software designed for TV viewing is fine)


    What I currently have
    ---------------------
    • A spare laptop (Dell Latitude D600) wating to go in, and ordered one of the laptop-auto-on modules found in the power supplies forum.
    • A universal auto/air/wall adaptor w/ a tip for my laptop (it's a Kensington 120W) that works through the cigarette lighter.



    My questions/problems are:
    --------------------------
    1. How to power the laptop.

    I really want to just use the cigarette lighter, but I've seen numerous cautions against doing so. However, I THINK I will be OK, since this is just a laptop & I don't have to power a screen?

    I would like to tap into the fuse block using a mini Add-a-Circuit found at AutoZone, and wire in a new Cigarette power outlet to the trunk, where I'll connect universal power adaptor to the laptop. This is to avoid tapping into any existing wires, which I know is a bad idea.

    2. Noise on my screen.

    I've tested my setup by connecting the laptop's video out to my screen & everything is great when the laptop is running on battery. However, when I power the laptop by plugging into the center console or dash power outlet, I get wavvy horizontal lines on my screen. I have no idea how to fix this.


    Please help a newbie!!!
    Don't use the tap, run a wire form the battery to the rear, to install the cigarrette lighter socket and use the Mobile Laptop power supply.

    As for the wavy lines, that is a tough one. You might try a power filter (from an auto parts store, BUT NOT A GROUND LOOP ISOLATOR), though I don't have a lot of hope for that solution, it is worth a shot. You could also look into "RF Chokes" and see if that would help.

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

  3. #3
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    Quote Originally Posted by Wiredwrx View Post
    Don't use the tap, run a wire form the battery to the rear, to install the cigarrette lighter socket and use the Mobile Laptop power supply.
    What is the downside to running a new wire from the fuse block, instead of the battery? I can tap into a slot that only has power when the ignition is on --- If I go straight to the battery, I have to worry about a shut-down controller (versus just letting the laptop hibernate when it looses power) because the power will always be on.

    If the shutdown fails (happen to me often... some program is not responding, and the shut-down won't complete) then I run the risk of draining my battery.

    I understand the need to run to the battery for a hard-wired PSU (w/ startup/shutdown controller), but the Kensington power supply for my laptop was designed to be used by a cigarette lighter -- is it unsafe to run a wire from the fuse block?

  4. #4
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    Quote Originally Posted by jwaters View Post
    What is the downside to running a new wire from the fuse block, instead of the battery? I can tap into a slot that only has power when the ignition is on --- If I go straight to the battery, I have to worry about a shut-down controller (versus just letting the laptop hibernate when it looses power) because the power will always be on.

    If the shutdown fails (happen to me often... some program is not responding, and the shut-down won't complete) then I run the risk of draining my battery.

    I understand the need to run to the battery for a hard-wired PSU (w/ startup/shutdown controller), but the Kensington power supply for my laptop was designed to be used by a cigarette lighter -- is it unsafe to run a wire from the fuse block?
    Well, it is "safer". The fuse panel is only desined to carry a certain amount of amperage theough it. You most likely will not exceed that, but why take the chance. Next, the fuse box, being that is has other devices on it, can cause unwanted interference, both from and to the laptop. Not probable, but possible.

    It is just the "better" practice to run power from the battery (and really the alternator) because that is where the electricity is generated in the car.

    You can use a relay to make the wire from the battery switched with the ignition. You can read up on relays by going to www.the12volt.com, and clicking on the "relays" link. They are simple to use, and will enable you to accomplish what you want with your laptop, and not worry about a flat battery.

    On a side note, how do you plan to handle startup of your laptop. You should do some searching for your options.

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

  5. #5
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    As for the wavy linnes on the screen:

    My guess is that when you plug it in to charge, you use the brick that came with it too? So DC-AC-DC. THat can cause noise, and if your car has the cig lighter right by the video wire, or the video controller's power is fed of the same as the cig lighter, then that noise goes there. You can then see the graphic depiction of the noise in your system.

    So you might have to run a wire from your battery.

    And as a side, how are you planning on getting audio from the laptop, and how are you planning to control the laptop?

    You cannot use the factory screen as a touchscreen. Also if you live in a bigger city, then FM modulator will produce noise. So some wires on your new car will need to be chopped up.

    YOu can always take it to an audio shop to get some warrantee on the work I suppose, but it will happen!
    Fusion Brain Version 6 Released!
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    30 Digital Outputs -- Directly drive a relay
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    Quote Originally Posted by 2k1Toaster View Post
    As for the wavy linnes on the screen:

    My guess is that when you plug it in to charge, you use the brick that came with it too? So DC-AC-DC. THat can cause noise, and if your car has the cig lighter right by the video wire, or the video controller's power is fed of the same as the cig lighter, then that noise goes there. You can then see the graphic depiction of the noise in your system.

    So you might have to run a wire from your battery.

    I did some interesting tests to try eliminating the video noise. I was hoping running it from the battery would fix things, but it didn't. Here is the sequence of things, and my conclusion follows:

    1. Running my laptop off battery, video out to the factory screen looks fine.
    2. Plugged in my laptop to the car's console lighter socket (using Kensington universal 120W auto/air/wall adaptor). I get wavvy lines.
    3. Tapped into the fuse block and added a new cigarette power socket. Plugged in laptop and still get wavvy lines.
    4. Ran the new cigarette lighter direct to the battery (wires outside the car). Still get wavvy lines.
    5. I happen to have a second identical laptop (I'll call it laptop B). With laptop A running off battery, output to the screen looks fine. Plug Laptop B into the cigarette lighter (with Laptop A still connected to the screen) & I expected to see the same video noise, because I assumed is was in the car's electrical system. However, no wavvy lines!

    This leads me to believe that the power inverter I'm using is introducing problems w/ the video output, not introducing noise in the car's electrical system. Which means that I might solve this by using a different inverter?

    Are there DC-DC car-specific power supplies for laptops? I've seen the ones sold here on mp3car, but these seem to be for powering standard ATX motherboards, not laptops?

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    Quote Originally Posted by Wiredwrx View Post
    Well, it is "safer". The fuse panel is only desined to carry a certain amount of amperage theough it. You most likely will not exceed that, but why take the chance.
    Forgive my complete lack of electrical understanding, but isn't that what the fuse is supposed to protect against? If you exceed the apmerage, it blows? So, if I tap into a 7.5amp fuse, and the fuse doesn't blow w/ laptop drawing max power, should that be fine, or is it still unsafe somehow?

    Quote Originally Posted by Wiredwrx View Post
    You can use a relay to make the wire from the battery switched with the ignition. You can read up on relays by going to www.the12volt.com, and clicking on the "relays" link. They are simple to use, and will enable you to accomplish what you want with your laptop, and not worry about a flat battery.

    On a side note, how do you plan to handle startup of your laptop. You should do some searching for your options.
    I'll check into the relay if I end up wiring direct to the battery. As far as the startup, I already ordered one of those startup controllers that are being sold in the power supplies forum. I have a mini-dock that I can tap into the power switch, and "electronically" press the power button when the car turns on.

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    Quote Originally Posted by 2k1Toaster View Post
    And as a side, how are you planning on getting audio from the laptop, and how are you planning to control the laptop?

    You cannot use the factory screen as a touchscreen. Also if you live in a bigger city, then FM modulator will produce noise. So some wires on your new car will need to be chopped up.
    I installed one of these for audio. It emulates a CD changer, so no FM modulation. The factory CD button toggles between the in-dash changer and the "virtual" changer. The other cool thing is that there's an Ipod connector that I wired into the center console. This Ipod is "CD #5" and the CarPC will be "CD #6". In the trunk are audio/video wires just waiting to be plugged in!

    Regarding the controls -- no, I won't be able to use the touchscreen (although a member of acurazine.com has figured out a way to send touchscreen presses to a PC via USB). I plan on using an RF remote. I actually have an extra Firefly remote left over from my Home Theater / HTPC build.

  9. #9
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    Quote Originally Posted by jwaters View Post
    Are there DC-DC car-specific power supplies for laptops? I've seen the ones sold here on mp3car, but these seem to be for powering standard ATX motherboards, not laptops?
    Nothing that is dependent or special for a particular brand of car.

    Let me suggest a couple of things based on your testing

    The fact that when A was on battery, and B plugged in has o ill efects indicates either that the supply is faulty or low quality. A power filter may help that. The other thing is, it can be similar to what an "audio" ground loop is, except for video. Again, the power filter might help. You might have to find the power wire for your Video unit for your NAV screen and put a filter on that, as well as one on the power wire for the Video screen itself. Noise like this is difficult to track down. Just because A worked when on battery, and B plugged in, doesn't necessarily mean it is the power adapter. The problem is most llikely related to all the grounds on all the power wires, and the ground on the video cables, having different paths and resistance, in all your devices. When A is not powered, one of those grounds is eliminated. I doubt it is noise from the power converter or the laptop itself, but it could be.

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

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    Quote Originally Posted by jwaters View Post
    Forgive my complete lack of electrical understanding, but isn't that what the fuse is supposed to protect against? If you exceed the apmerage, it blows? So, if I tap into a 7.5amp fuse, and the fuse doesn't blow w/ laptop drawing max power, should that be fine, or is it still unsafe somehow?
    .
    It is not only about safety and ther fuse, but the "cleanliness" of the power.

    But, as for safety, first that assumes you pull the power AFTER a fuse in the box. Some people find unused sockets and pull power from there. The other problem is that fuses are installed to protect the circuit after it. Fuses also fuse for 125 percent of the max power rating of the circuit. No matter how you slice it, you will be drawing more power through the entire circuit because of the laptop. Is it a lot more, not necessarily, but it is more. This is only compounded if one uses a "rea" carputer.

    It is just not "good" practice. Like putting the toilet seat down after use. Will not doing it cause any issues, probably not, but the wife/gf might not like it and eventually, it could lead to problems, or a complete meltdown. I have seen worse ideasw, it's just not the "best"

    Michael
    ...I love the French language...especially to curse with...Nom de Dieu de putain de bordel de merde de saloperies de connards d'enculés de ta mère. You see, it's like wiping your *** with silk, I love it.

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