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How can I power my car from a standard outlet?

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  • #16
    Okay, so these will work to supply me with a 12 volt power supply that is safe to run my electronics from?
    Enter the LOTUS...
    (more info here)


    Pre-build thread


    Planning: ::::::::::::
    Parts: ::::::::::::
    Build: ::::::::::::
    Test: ::::::::::::
    Install: ::::::::::::

    Oh, yeah, and build the car... ::::::::::::

    Comment


    • #17
      Safety is relative and it depends on the design, not on the design principles.

      IE - A Linear supply will destroy electronic equipment just as easily as a SMPS if overvoltage and over current protection have not been correctly implemented.

      Depending on the size and construction of the transformer, a 30A Linear supply can have around 20v to 28v on the input to the regulator, this will blow most electronic devices designed for a nominal 12v if the regulators short and overvoltage protection is not tripped or designed correctly. SMP supplies are increasingly used in Commercial and Amateur Radio systems with transceivers worth anywhere from $1,000 to $18,000.

      Unfortunately with everything in electronics only a manufacture could give you a money back guarantee if their PSU blows your equipment. Bet it would expensive though!
      Palm sized ainol MiniPC, 8" Transreflective PRO, Win10, Reverse camera, Dual 10HZ GPS RX's for Speed Display & Sat Nav, FM-DAB & Phone Modules, iDrive interface. T-Screen HVAC control, custom microcontrollers, microcode and FE.

      Comment


      • #18
        It sounds like you do not want any reconnection, hence you are looking at a battery charger option.

        [ Yes, using an ATX supply means reconnecting the load off the car battery to the ATX. Because you want to power other car stuff as well, it means disconnecting the car battery and using the ATX instead. ]


        You can't connect a 12V power source to a car battery - it needs to supply higher than the battery voltage - ie, 13.2-14.4V.
        And to avoid switching dropouts (eg, when switching lights on), a battery is required.
        Hence add a suitable charger.


        Many use a dual-battery system instead.
        Where one battery can easily handle the expected "non-charging" use, it is connected via a battery isolator (typically a relay controlled by the charge light) and fuses at each end.
        In your case, maybe it should be rigged as a spare cranker - ie, since your lights etc are connected to the normal battery, use the main as you "load" battery. The aux battery is then the emergency jumper battery. (Mots power their extra loads off the aux battery.)

        Comment


        • #19
          Originally posted by OldSpark View Post
          It sounds like you do not want any reconnection, hence you are looking at a battery charger option.

          [ Yes, using an ATX supply means reconnecting the load off the car battery to the ATX. Because you want to power other car stuff as well, it means disconnecting the car battery and using the ATX instead. ]
          The goal here is to be able to simply hook up the power leads and maybe flip a switch or two.
          Originally posted by OldSpark View Post
          You can't connect a 12V power source to a car battery - it needs to supply higher than the battery voltage - ie, 13.2-14.4V.
          And to avoid switching dropouts (eg, when switching lights on), a battery is required.
          Hence add a suitable charger.
          The converter I'm looking at is rated for 13.8v (+/- 0.5v).
          Originally posted by OldSpark View Post
          Many use a dual-battery system instead.
          Where one battery can easily handle the expected "non-charging" use, it is connected via a battery isolator (typically a relay controlled by the charge light) and fuses at each end.
          In your case, maybe it should be rigged as a spare cranker - ie, since your lights etc are connected to the normal battery, use the main as you "load" battery. The aux battery is then the emergency jumper battery. (Mots power their extra loads off the aux battery.)
          My car is a sports car , I would like to keep the weight down as much as possible.
          Enter the LOTUS...
          (more info here)


          Pre-build thread


          Planning: ::::::::::::
          Parts: ::::::::::::
          Build: ::::::::::::
          Test: ::::::::::::
          Install: ::::::::::::

          Oh, yeah, and build the car... ::::::::::::

          Comment


          • #20
            You can get some relatively compact, switch mode chinese made power supplies that are capable of 20 amps from eBay for about $40 (available in 12V, 15V, 24V and etc). They even have a potentiometer to adjust the voltage slightly by about +/- 10%. That's what I did to my car. I got a 15V 20 amp supply, adjusted the output to 14V, then connected the output with a high current diode (of which you can find in an old ATX power supply) in parallel with the car's electrical system and installed everything neatly near the spare tire compartment in the trunk.

            Bam, now I can run an extension cord to the car whenever I want to work on the carpc or have the music running while Im in the garage.

            Comment


            • #21
              Originally posted by nobb View Post
              You can get some relatively compact, switch mode chinese made power supplies that are capable of 20 amps from eBay for about $40 (available in 12V, 15V, 24V and etc). They even have a potentiometer to adjust the voltage slightly by about +/- 10%. That's what I did to my car. I got a 15V 20 amp supply, adjusted the output to 14V, then connected the output with a high current diode (of which you can find in an old ATX power supply) in parallel with the car's electrical system and installed everything neatly near the spare tire compartment in the trunk.

              Bam, now I can run an extension cord to the car whenever I want to work on the carpc or have the music running while Im in the garage.
              Are you talking about something like this?

              How do you have that connected to the car, how do you keep it from over-charging your battery?
              Enter the LOTUS...
              (more info here)


              Pre-build thread


              Planning: ::::::::::::
              Parts: ::::::::::::
              Build: ::::::::::::
              Test: ::::::::::::
              Install: ::::::::::::

              Oh, yeah, and build the car... ::::::::::::

              Comment


              • #22
                That's similar to the one i have but not exactly. It would work though. Just keep the output voltage at 13.5 - 14v and you can simply hook it up in parallel to the car's electrical system. No need to worry about overcharging.

                Comment


                • #23
                  I decided to over-complicate this a little, I wanted to lock out the starter when the car was plugged in, and to require the key to use the computer when the car is plugged in, and automatically disconnect the battery when I plugged the car in. This way I can use this power supply, which is much cheaper, but outputs 12volts. Oh, and I added push-button ignition
                  Attached is a rough schematic of the system.
                  Attached Files
                  Enter the LOTUS...
                  (more info here)


                  Pre-build thread


                  Planning: ::::::::::::
                  Parts: ::::::::::::
                  Build: ::::::::::::
                  Test: ::::::::::::
                  Install: ::::::::::::

                  Oh, yeah, and build the car... ::::::::::::

                  Comment


                  • #24
                    This definitely seems over complicated.

                    Here is my advice... Find yourself some sort of quick connect cable ends that will handle 15VDC @ 30A, wire the female end up directly the car battery (with a suitable fuse) - and mount it so you can access it easily when you need to plug in the car. Under the hood, perhaps. Wire up the male side to a regular car battery charger (~$100 for a nice one, you can probably find one for $25 on eBay or craigslist).

                    Then, when you want to have the computer on, you just plug the charger in. No need to wire anything else differently. And if you're using a battery isolator, wire up the charge wire to the central post (same one as the alternator) so that both batteries are charged when you plug in.

                    Comment


                    • #25
                      The reason I decided to do it the way listed above (post 23) is because; a) for the reasons listed there, & b) because I couldn't find a battery charger that could output that high a sustained amperage that was in budget. Take a look at the .txt file attached to that post, I know its crude but you should be able to figure out what is going on.
                      Enter the LOTUS...
                      (more info here)


                      Pre-build thread


                      Planning: ::::::::::::
                      Parts: ::::::::::::
                      Build: ::::::::::::
                      Test: ::::::::::::
                      Install: ::::::::::::

                      Oh, yeah, and build the car... ::::::::::::

                      Comment


                      • #26
                        I tried looking at the .txt file, but it doesn't seem to have formatting - its just a single line of text for me, and I couldn't get it to line up. A .gif or .jpg might be a bit more helpful.

                        I did a quick search and found a 30 amp battery charger for $80 at Amazon. Even this, I think, is overkill. You had said you needed 30 amps - but that is a LOT. 30 amps @ 12v is 360 watts. 360 watts is enough for my entire home entertainment center, including 5.1 surround sound receiver and speakers, desktop computer, and a 40" LCD (total: 250 watts at idle, 300watts when I'm watching a movie) I would guess that most carpc setups use 150 watts at peak (playing a movie with the speakers blasting) - average around 50W when in use, and idle at 25W. Of course I'm making a lot of assumptions here, it's certainly possible for an audio system alone to consume 500W, they're just rare.

                        Remember that your charger doesn't need to be providing 100% of the power drain at peak, it only has to provide more than 100% of the average power - in fact, even that isn't necessarily true, as your battery will have some charge in it and you can leave the charger plugged in over night to top it off after you're done.

                        Comment


                        • #27
                          At the time I posted this thread I was planning on running an OPUS 360, and a midd-low end graphics card. The idea is to be able to run the computer and lights with out any drain on the battery for things like updates, but also at a car show (hence the need to disable the starter). I figured that the computer running at full power playing HD video on at least 3 monitors and all the lights and everything else that would need to be run at a show 30 amps would be adequate. I have since decided to go with a M4-ATX and lower power USB graphics cards, but that is still gonna need a lot of power. Attached is the schematic, this time with Windows formatting instead of UNIX formatting.
                          Attached Files
                          Enter the LOTUS...
                          (more info here)


                          Pre-build thread


                          Planning: ::::::::::::
                          Parts: ::::::::::::
                          Build: ::::::::::::
                          Test: ::::::::::::
                          Install: ::::::::::::

                          Oh, yeah, and build the car... ::::::::::::

                          Comment


                          • #28
                            Damn, that is a lot of power!!!

                            I think you're right, with 3 monitors and lights and stuff, you can hit 20 or 30 amps for sure. Also, good call on disabling the starter. It would suck to have somebody try to steal your ride at a show!

                            Comment


                            • #29
                              Originally posted by CyberBill View Post
                              Damn, that is a lot of power!!!

                              I think you're right, with 3 monitors and lights and stuff, you can hit 20 or 30 amps for sure.
                              Yep, and all this in a 40 year old 1500 pound sports car

                              Originally posted by CyberBill View Post
                              Also, good call on disabling the starter. It would suck to have somebody try to steal your ride at a show!
                              Yeah that would really suck, but I'm not expecting to meet very many people who would be capable, let alone willing, to actually get into the car.
                              Enter the LOTUS...
                              (more info here)


                              Pre-build thread


                              Planning: ::::::::::::
                              Parts: ::::::::::::
                              Build: ::::::::::::
                              Test: ::::::::::::
                              Install: ::::::::::::

                              Oh, yeah, and build the car... ::::::::::::

                              Comment

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