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Car Computer Install: Power Structure

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  • Car Computer Install: Power Structure

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    Sean Clark, from mp3Car, shows us an overview of how each component will be powered in the vehicle. He outlines the importance of in-line fuses for each positive cable. Power distribution blocks will be used to give each individual component power and ground. Grounding all the components in one place is important to avoid noise being introduced into the system. If you are able to ground directly to the negative terminal on the battery, this will help alleviate noise as well. Monitor power is provided by the M2-ATX power supply in the computer. "Filtered" 12V power is required for most monitors as they aren't set up to the handle voltage fluctuations most automotive power systems supply. In this case, the Lilliput 669 needs filtered power. Accessory wires are run to each component and provide switched 12V power to tell each component to turn on with the ignition status of the vehicle.
    Have a product you would like to sell on the mp3Car Store? PM me for more information.

    Have a car computer question? Ask me by emailing the store.

  • #2
    Hi. Is it possible to give me some information as to where you get all the wires and fuse lines, power distribution block that replaces the hookup battery and etc? A link of it would be nice if you dont mind. Thank you for the tutorials that you give out. It give me a clear sense on what you need but I also have a lot of questions to ask too, but these are just a few for now. Thanks again.

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    • #3
      ^ i believe some of the connectors are available from the mp3car store. ah, i just checked.. if they are there, i can't find them... i know they used to carry some of that stuff...

      otherwise, i use 'amp power kits' form walmart. they include more then you ever need. i have also read of many people getting the wiring and connectors from knuconcepts.com.


      video comments (you guys gotta love me by now!):

      i am a little leery of recommending new members to cut off their factory battery connector-- many cars have multiple wires going to a factory molded connector, some with more wires then the aftermarket terminals provide(my car is one of these-- off the top of my head, there are 4 large-guage wires on the terminal harness from the factory).

      instead, i recommend to use a ring terminal like this, as there is usually a bolt on the factory battery terminal that it will fit on that you can use without modifying the factory power system.

      note, i recommended a setscrew-type terminal because the thinner crimp-type terminals are not as easy to install, because many people new to them do not use enough force to crimp them, and the wire falls out later, causing all sorts of problems. crimp-type terminals are really dependent on how good the installer is at crimping, and can be just as good as any other connection, but can be a lot more difficult without the correct tools, or time taken to make the connection..



      and to point out the fusing again, as it is a point that can never be made enough. audio competition rules state that all power wires MUST be fused within 18" of the battery, though, as sean stated--the fuse really shouldn't be farther then 12" from the battery connection. i have installed amp kits in 4-5 vehicles, and the 12" rule is always enough to allow for correct routing, anything more and you would start to need excessive loops to keep the fuse accessible for later..



      i love the amp--i might need to try that design next---- it would prevent all the problems standard circuit board-based designs have, like emitting audio. i'm guessing that's one of those rare 1.21 jigawatt amps right? i haven't seen one of those for years...


      grounding: some cars have the battery in the trunk, near the carpc-- in this case, it is preferable to connect directly the battery.

      if the vehicle has the battery mounted in the front of the car, and you choose to run the negative wire back to the battery, it is recommended to run 1 gauge higher for the negative wire to reduce the amount of resistance on that to prevent the devices from overheating. (remember wire gauge goes backwards-- so if you ran a positive 8ga, run a negative 4ga) i consider this more of a "audiophile" route. there is some advantage in powering the devices, and keeping power problems out of the aftermarket power system, but there is zero advantage when it comes to the large extra cost of copper wire.

      in 99% of installs, mounting to the vehicle body is perfectly acceptable. in most cases, using a seat bolt, or some other major bolt is desirable as it will be solidly connected to the car. many problems with noise are due to the multiple layers of thin metal that today's cars are made out of, and connecting to a solid body point bypasses some of these issues(but never guarantees that those issues can't happen).

      when bolting the ground wire to the car, be sure to sand the paint away from the area that the bolt is so that the ground wire can get good metal-to-metal contact.



      and finally-- the accessory wire , the point that has caused so much confusion in the newb section..

      just as sean said, that is the exact method that i always recommend connecting it first. some installs have a "turn on pop" where the speakers pop when everything first turns on. there are a couple solutions to this, though i recommend looking into those solutions only after the install shows the problem.

      i think that's it good job on the video!
      Last edited by soundman98; 08-28-2011, 01:24 AM.
      My OLD 2001 Mitsubishi Eclipse GT:
      "The Project That Never Ended, until it did"


      next project? subaru brz
      carpc undecided

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      • #4
        I think I have that amp
        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

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        • #5
          Originally posted by 2k1Toaster View Post
          I think I have that amp
          Did yo have the "SE" or "LE" edition? I heard the "SE" has "AMP" in italic font and comes with a separate SUB out.

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          • #6
            Car Computer Install: Power Structure

            hmmmmmm
            i think about it

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            • #7
              Haha love the comments guys. The amp is actually 1.4 jigawats. I needed it for my altma stock speakers since they are so powerful.

              Couple notes:

              - we did in the end NOT take off the battery terminal, and INSTEAD used a bolt that was already on there. I didn't change the video because I think you learn more about what exactly is going on when you think about it in terms of a distribution block instead of ADDING to the positive that is already there.

              - we did end up GROUNDING TO THE BATTERY. In a later video about noise we will find noise and troubleshoot it to find the solution is grounding to the battery. I wanted to keep this in here though because most amp kits and car computer install guides tell you to ground as close to the car pc as possible. However - people will need to learn about noise and troubleshooting it. So later I think its a good progression from this step.

              Thanks for all the feedback, next video coming very soon.

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              • #8
                Originally posted by optikalefx View Post
                Haha love the comments guys. The amp is actually 1.4 jigawats. I needed it for my altma stock speakers since they are so powerful.
                hmm, i haven't looked at that brand for a while, i guess i'll need to look again, i thought they kept the same power ratings..

                Originally posted by optikalefx View Post
                - we did end up GROUNDING TO THE BATTERY. In a later video about noise we will find noise and troubleshoot it to find the solution is grounding to the battery. I wanted to keep this in here though because most amp kits and car computer install guides tell you to ground as close to the car pc as possible. However - people will need to learn about noise and troubleshooting it. So later I think its a good progression from this step.
                did you already shoot that video?

                because there are SO many different noise problems and just as many different solutions to each problem..
                My OLD 2001 Mitsubishi Eclipse GT:
                "The Project That Never Ended, until it did"


                next project? subaru brz
                carpc undecided

                Comment


                • #9
                  Yea, the whole series has been completed shot and edited.

                  Its true the range of noise problems is massive, but we go over one of the most common ones that we see so often, and by grounding to the battery instead of the chassis we were able to eliminate most of it.

                  Comment


                  • #10
                    yes, that does correct the issue-- kinda like throwing a cell phone against a wall after it auto-corrects what you type-- a little over the top(mostly a reference to the extra cost of copper wire needed for this), but it does fix the problem..


                    (note, i am sure you have a excellent grasp on the subject, many of these notes are more for new members who might be following this video series to learn how to install a carpc, as there is no single solution to any carpc-related subject..)

                    i have seen plenty of people that run a wire back to the battery, but without using a larger gauge wire, well, time for a water analogy:


                    if you have a glass of water(battery/power source) and 2 same diameter, 2ft long straws(power wires).

                    it is relatively easy to draw water from the glass from the first straw but is slightly more difficult to blow that water back into the glass through the second straw.. if you change the second straw for a straw 2x's the diameter, suddenly it is just as easy to draw water from the glass as it is to blow it back into the glass.

                    this is how electronic devices feel, and i have read of many reports of audio amps running hotter, or burning up because of the use of same-sized power/grounds going to the battery.


                    the reason for the short ground wire directly to the car is that the cars metal, while thin, is a very large sized conductor--larger then most wires you can buy, which is the equivalent of you using a very large straw to blow the water back into the cup.. because the amp needs to work less to get rid of 'spent' power, it runs cooler and more reliably.

                    the problem lies in the manufacturing of today's cars, those thin pieces of metal that make up most cars are spot welded together, and many times certain portions of the car have a higher resistance to the battery then other portions of the car. and so begins the ground loop problem--if you bolt the ground wire to one of those spots that has a higher resistance, the negative power finds a easier path back to the battery, usually resulting in noise from speakers, or all sorts of weird issues.

                    running the ground wire back to the battery can alleviate many of these problems, but because all wire has a certain amount of "voltage drop"(power like in a car traveling over any distances will loose voltage--there are many calculators to determine this, and also better descriptions elsewhere), it is also possible that you could still have a ground loop using this method if some part of the car has a better path to ground--not likely, but always possible.
                    My OLD 2001 Mitsubishi Eclipse GT:
                    "The Project That Never Ended, until it did"


                    next project? subaru brz
                    carpc undecided

                    Comment


                    • #11
                      Yea we used 8 gauge wire for the positive run to the trunk and another 8 gauge for the negative. In the troubleshooting video we go over using ground loop isolators as well as scratching back paint on the chasis to try to make a good ground connection.

                      But yea for new users, if you *can* go back to the battery for ground its *usually* the best fix.

                      Comment


                      • #12
                        Sorry - this is a bit late, but...
                        Originally posted by soundman98 View Post
                        audio competition rules state that all power wires MUST be fused within 18" of the battery...
                        Ah - that is one source for that rule!

                        IMO there can be no such rule in general...
                        In some applications, fusing is dangerous (eg, high current DC systems; usually above 3,000A), and I have seen several instances where adding fuses (especially within 12" or 18") has INCREASED the hazard risk!


                        IMO the rule should be that adequate protection is provided.
                        Protection is usually via 2 means - "physical" (as with the starter-motor wire that is almost always un-fused (in typical and non-modified situations) yet it carries typically a few hundred Amps) and (2) "fusing" (including circuit breakers, or temperature or current-sensing trips etc).

                        The fusing "within x" of a battery" should be read as "as close as practicable to the battery" (without itself causing a hazard). (FYI - in some applications, fusing is NOT allowed in the same room or compartment as the batteries.)


                        Many installations do not have fusing and are considered quite safe - eg, dual batteries in engine bays where the interconnection is a copious gauge heavy insulated wire, maybe through additional insulation like garden-hose or a plastic-tube, else additional physical protection (metal conduit to prevent insulation crush in accidents etc).

                        As to certain car-competition rules that allow battery isolation switches to be in the hot (+ve) battery circuit with the isolator switch in the cabin - or worse, a remote rear corner - ah well, that's their funeral. As to those that mandate that situation (eg, if the isolator also has to kill the engine)... IMO stupid and risky. (Battery ground isolation is what should be used, but this won't kill an engine. But IMO "engine kill" and "battery isolation" are two separate requirements. They can be interlocked, but that requires complexity that stretches reliability etc.)
                        [ By isolation switch I man a full-current carrying switch - not a switch that control remote relay(s) - but they have reliability and hence other safety issues too. ]


                        Sorry for this delayed reply -cum- hijack. But if enough people understand the issues, maybe one day the Rules will be modified appropriately. (Alas I recall when certain scrutineers claimed that ground isolation was illegal! Related regulations/rules have since been notated (or changed) to allow the far safer ground isolation.)
                        Last edited by OldSpark; 08-29-2011, 02:14 AM.

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                        • #13
                          YouTube.......

                          Not sure what format you guys are shooting these videos in, but it would be nice to have them available on YouTube. Any reason they aren't? I'm having a hard time viewing some on my xoom tablet.

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                          • #14
                            thank you for you sharing.

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                            • #15
                              Signal wiring question

                              I have basically copied your build and have a question on the signal wiring. I was reading the manual for the power supply (imagine that..lol) and noticed they have a spot to send the signal wiring to the amp(s). It also stated that this helps the "pop" that some people experience. Do you suggest not using that feature of the power supply? If so, could you explain the reasoning?

                              Thanks for the videos too!!!

                              JM

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