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My idea for powering carpc off wall at home (cheaply!)

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  • My idea for powering carpc off wall at home (cheaply!)

    Hi.
    Everytime I want to sync my music, or install stuff, it is a big hassle. The reason is that I do not feel comfortable running the carpc off battery for extended periods of time. Therefore, everytime I want to install something/sync my music/whatever, I have to unscrew everything, take my computer indoors, and use it there. It would be MUCH more convenient if I could just use the computer in the car, but being able to "plug" the car's electrical system into the wall at home so that the battery does not get drained. So here is my idea.

    I came across this site:
    http://www.antennex.com/preview/archive3/powers.htm
    I am mostly interested in the part which suggests connecting the +5 volts of 3 computer power supplies together to obtain 15 volts at a fairly high current (~25 amps). I have a TON of computer power supplies laying around, so this is no problem. To reduce the 15 volts to the ~13.8 volts that a car's electrical system requires, the site suggests connecting one of two high current diodes to drop the voltage to approximately that level. With this ~13.8 volts availiable at a fairly high current, I could then connect the +13.8 volts and -ground in parallel with my car's electrical system, then run my carputer without fear of a drained battery. Before I try something like this out, I would like to hear some opinons. Is this a good idea? Is there anything I have overlooked?

    Also, the most difficult part is where I can find a diode which can handle such fairly high currents cheaply. I would prefer to buy locally and the only store that I know of that carries electronic components is:
    www.active123.com
    I have not been able to find a suitable diode from looking at this site (maybe I am using the wrong search terms?)

    Or could I go to a car junkyard to find these high current diodes? I know that high current diodes are connected to alternators to convert the AC > DC. But what exactly do automotive diodes look like? I've tried to do a image search, but I couldnt really find a good picture. Where under the hood would I be able to locate these diodes? Are they usually obviously exposed, or are they hidden in something? I am a complete noob when it comes to anything under the hood of cars.

    Suggestions would be welcome. Thanks.

  • #2
    Originally posted by nobb View Post
    Suggestions would be welcome. Thanks.


    Don't do it.



    Unless you do it right you could

    a) screw up your cars electrical system

    b) screw up your house's electrical system (not sure how US supplies are done but if they are not fused properly and fire could ensue)

    c) screw up your person if you touch any of many wrong contacts that will be available to you.

    Comment


    • #3
      IF you still decide to do it, get an MBR3045PT - SCHOTTKY RECTIFIER,45V,30AMP available at Active.

      Good luck!
      If it ain't broken, open it to see what makes it "tick".

      Comment


      • #4
        wtf.

        just use the +12v output from one supply

        Comment


        • #5
          see, thats the benefit of using a laptop for your setup. if i want to work on my carpc for a lengthy period of time I run a a/c line from the wall to ac connector my laptop came with, then plug the laptop in!

          mwuahahhaha

          it's kindof runny looking right now as i have a big orange cable going in through my rear window.
          Car : 00' Chrysler 300M
          Speakers : Rainbow Audio SLC 265 | Subs : Diamond Audio D6 12" Subs X2
          Amp's : Hifonics ZXi 6006 AB | Hifonics BXi 1606 D
          CarPC: HP Laptop AMD Sempron 3000+ | 1.5GB RAM | DVD+RW | 80GB 5400RPM HD | ATI R200 Video

          Comment


          • #6
            I do have a switch so I can disconnect my car pc from the battery.
            ( http://www.disco3.co.uk/gallery/disp...bum=851&pos=10 )
            On the PC's side, I do have a connection for the 12V (ignition and constant) and the ground. As such, I connect a 12V source (old power supply from a PC case) when playing around with the car pc. Since the screen is powered through the PC's M2-ATX , I do have everything I need.
            No need to uninstall the car pc (which would be quite hard to do avery time).
            2 minutes and I'm set to go.
            Still thinking of creating a type of plug which could make it simplier to connect PC and 12V source.

            Comment


            • #7
              Using the +12 volts would not work, because if you connected 12 volts directly to your car battery (and electrical system), then your car battery would slowly be drained. This is because when fully charged, your car battery should be at about 12.6 volts.

              I figure that if I could supply approx 13.8 volts of voltage which a fairly high current availiable (pretty much supplying power like an alternator), then my car battery could be put on floating charge, and all electronics could be powered.

              Comment


              • #8
                dont do it

                Just get an external hdd kit or something from NewEgg with a usb 2.0.
                Dump your stuff on that and be done with it.
                03' Toyota Tundra T3 Special Edition - Polk Audio speakers - Sony 4ch amp - RF Sub amp
                Carputer Planning |---------*|
                Overall Implementation |---------*-|
                (Stereo complete)
                Computer installed and working

                Comment


                • #9
                  Make an isolator

                  I have been planning to do this, too. What you need to do is use the 12 volt rail from one of those old power supplies you have. Just make sure the 12 volt rail makes a high enough current for your computer (old ones don't make a lot). Then make an isolator with a DPDT switch (Dual-Pole, Dual-Throw, make sure it is rated for enough current). I attached a simple diagram. That'll do it. Then you just plug the computer PSU into the wall, flip the switch from battery power to PSU power and you're ready to rock and roll.


                  P.S. I hope you can make sense of the schematic, if not PM me.
                  Attached Files
                  Max Messinger
                  Computer Expert
                  Car Newbie

                  2000 Maxima CarPC Progress: 99%--Basic computer fully installed, full stereo overhaul planned for the future

                  Comment


                  • #10
                    What v1per has is the way I would do it, though I would actually use a 12v Automotive relay and install the power supplies in the car. Just running an extension cord from the house.

                    Have the power for the computer go through the relay, then when the AC power supplies are turned on, have the 12v trigger the relay to switch from car battery to power supply.

                    So, common on the relay goes to the PC, normally closed is car battery, normally open is the AC power supply. The relay is triggered by 12v and ground off the AC power supply. That way it will automatically switch whenever you have AC provided. You can even use a diode or another relay to have it automatically supply power to the ACC wire for the computer, so it'll power on automatically.

                    Comment


                    • #11
                      another option is to mount the harddrive in a removable caddy like the Vantec EZ Swap. Buy two of them

                      Place one in your desktop computer, and one in the carpc. Want to work on the carpc? yank the harddrive out, very easy/quick to do. Go inside, pop it in your computer and add whatever you want to it.
                      Car : 00' Chrysler 300M
                      Speakers : Rainbow Audio SLC 265 | Subs : Diamond Audio D6 12" Subs X2
                      Amp's : Hifonics ZXi 6006 AB | Hifonics BXi 1606 D
                      CarPC: HP Laptop AMD Sempron 3000+ | 1.5GB RAM | DVD+RW | 80GB 5400RPM HD | ATI R200 Video

                      Comment


                      • #12
                        Originally posted by Ruffy View Post
                        another option is to mount the harddrive in a removable caddy like the Vantec EZ Swap. Buy two of them

                        Place one in your desktop computer, and one in the carpc. Want to work on the carpc? yank the harddrive out, very easy/quick to do. Go inside, pop it in your computer and add whatever you want to it.
                        except for installing things which rely on certain files being placed in the windows directories. Even if you say install to this folder, the nuts and bolts of the program is going to go in the current windows directy, ie not the carPC.
                        Fusion Brain Version 6 Released!
                        1.9in x 2.9in -- 47mm x 73mm
                        30 Digital Outputs -- Directly drive a relay
                        15 Analogue Inputs -- Read sensors like temperature, light, distance, acceleration, and more
                        Buy now in the MP3Car.com Store

                        Comment


                        • #13
                          I think the easiest and cheapest solution, provided you already own the hardware, would be to just config your machine via remote desktop thru wireless iNet.

                          I'm not sure if your carpc has wireless Inet, along with your home, and you're in range where you park your car.

                          But if so, leave your carpc on, activate remote desktop. Go into the house, connect to the carpc on your desktop in your house via wireless inet. You can transfer files and do just about anything you can do sitting at the pc from inside your house. When you're done, just shut down the carpc remotely.

                          No need to spend more money or hook up anything. Then again, if this is not possible, then ah well...

                          There's sync programs that allow you to auto shutdown the PC once completed too
                          www.mobile-effects.com

                          Free file hosting, picture gallery hosting for installs, PM me.

                          Internet's first Front End Skin browser, featured installs, downloads, links, informative articles - all free to registered users.

                          Comment


                          • #14
                            Hmm...I really do like Viper's idea and I might try it out if I have time. However, I really do want a high current voltage supply which can charge my batteries if I need. The remote desktop or external drive ideas really are not an option, because sometimes I might perform various types of tasks which would require the computer to be on overnight, or long hours (such as defrag).

                            Just to give you guys an update, I was bored yesterday and I have sucessfully managed to get 15 volts by hooking up 3 PSU's together. I powered a 50 watt automotive light bulb. The PSU's are rated at 30 amps on the 5 volt rails, so in total I can theoretically get 15 x 30 = 450 watts! Now if I decide to pursue this further, I would need to drop the voltage to a safe ~13.8. I am ALSO happy to say that I realized that switch mode power supplies have high current diodes. I actually ripped open one yesterday to obtain a 60 amp diode for my tank circuit (another story). Since I have 30+ PSU's laying around, I might try to get some diodes to drop that 15 volts.

                            Comment


                            • #15
                              That should work. My idea only works for the PC alone and not the whole car.

                              I like the relay idea, but it would be much, much more expensive than simply using a DPDT and flipping it when you need the AC power. Also, I guess I didn't say it but I meant to put the PSU in the trunk (that is what I plan to do, put the PSU in the trunk with an extension cord under the carpet with the spare tire).

                              As far as remote desktop, that doesn't really solve the problem. He wants to be able to leave the computer on for long periods of time. That said, you could use remote desktop for this type of maintenance, but you would still need an AC->DC power supply.

                              I really, desperately need to make a setup like this, but I need some money first...
                              Max Messinger
                              Computer Expert
                              Car Newbie

                              2000 Maxima CarPC Progress: 99%--Basic computer fully installed, full stereo overhaul planned for the future

                              Comment

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