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Would This Setup Survice Crank?

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  • Would This Setup Survice Crank?

    Hi, i'm kinda new to this, and searched around, got most of my power flow mapped out using other topics and thread, but just had last couple questions and doubts, i made a map of the power source and supply, its pretty simple to comprehend, the diode between the 2 batteries is still just an idea, most likely i'll break the circuit wired to the ignition so it'll break that circuit when i crank, the battery i've acquired from a APC battery backup UPS, its 12v, and thought it would fit this setup. I just would like to know if this setup would work, and also
    -what dc to dc supply do i need and does mp3car.com carry it?i'm sure i wouldnt need the opus since i already have a backup battery keeping the carpc alive.


    -Thanks, this forum has really been a lot of help already, just need a final touch to complete this setup on paper and join the rest happy with pc's in their car!

  • #2
    I think this one will work. Depends on your power draw.

    http://www.mp3car.com/store/product_...products_id=67

    I'm not a tank circuit expert, so I'll leave it to them, although this looks similar to other circuits I've seen on the boards. I think you need a "Schotkey" diode, which can handle a lot of power. If you haven't already, search on terms like "tank circuit diagram" and so forth.
    Originally posted by ghettocruzer
    I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
    Want to:
    -Find out about the new iBug iPad install?
    -Find out about carPC's in just 5 minutes? View the Car PC 101 video

    Comment


    • #3
      yea i forgot to mention the power draws, heres what i want running so far off the powersupply, and the motherboard:

      -One (1) Maxtor 80GB 7200RPM Hard Drive
      -4 USB Connections
      -GPS
      -Touch Screen (liliput 7")
      -Wireless 802.11 G USB reciever
      -Removable Thumb Drive
      -3 Small Fans for cooling the CPU(1 of which for HD)

      -MAYBE a cd reader-writer, but i want this to work first, and the optical drive isnt a priority.

      Comment


      • #4
        i have the M1-ATX runing with out a tank and it always survives crank. (sorry about spelling killer headache)
        1990 Jeep Cherokee
        2000 VW Golf TDI 4dr
        2005 VW GTI MKIV - SOLD

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        • #5
          ok the M1-ATX does seem like it fits this setup, but adding that backup battery, would that help? like would the backup battery allow me to put more load on the M1-ATX, obviously the battery will be set to match the higher watts being consumed by the power draws, also does the M1-ATX have like a safety, like even if its got a lot power supply, like this tank circuit, would the M1-ATX ONLY give 90 watts, or is it capable of giving out more, if supplied with more..? thanks.!

          and also does someone have a detailed pic of the M1-ATX, i jus wanna see what the terminals looks like on the supplied power source on the M1-ATX, thanks.

          Comment


          • #6
            In simple terms, 90 watts means 90 watts. Power supplies can often supply a peak that is higher but only for a very short time.

            I think you're misunderstanding the concept of power draw vs. supply. Your shiny new M1-ATX will supply what your computer requests it to supply up to the 90 watt limit (okay you EE's, I'm just illustrating the concept as simply as I can). The components in the power supply are designed to do this and probably have some type of safety "cutoff" that will prevent them from supply more than your setup will ask.

            The fact that your battery can supply WAY more than 90 watts doesn't affect the power supply. The way you phrased it, if this were true, when you plugged your vacuum cleaner into the wall outlet it would explode because of the amount of power that COULD be supplied.

            Now, you do want a regulator in the circuit because your car's electrical supply can and does vary depending on whether the car is running and what's happening to it at the moment. Sometimes that can result in voltage spikes that exceed the capacity of the power supply. You don't want those passed on to your power supply. The regulator will keep that from happening.

            I don't know if the M1-ATX includes power regulation in it or not. Others can tell you.

            I can tell you -and DON'T TRY THIS YOURSELF, that I have run my PC power supply and setup directly off of my battery with no regulation at all and it survived just fine. But I don't now and am not going to do so in the future.
            Originally posted by ghettocruzer
            I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
            Want to:
            -Find out about the new iBug iPad install?
            -Find out about carPC's in just 5 minutes? View the Car PC 101 video

            Comment


            • #7
              the M1 does regulate, it can go down to 5.7 volts for cranking, and the max power input is 30 Volts. so it has regulation built in.
              1990 Jeep Cherokee
              2000 VW Golf TDI 4dr
              2005 VW GTI MKIV - SOLD

              Comment


              • #8
                ok i get the idea, only 90 watts are supplied and only 90 at peak, ok on the regulation of power supply, using what i have above, adding a small battery, wouldnt that be a regulated power supply? once again i'm new at this, but would adding that backup battery help? atleast the supply a standard 12v?

                Comment


                • #9
                  It helps keep the power dropping BELOW 12 volts. But you can still get spikes above. But that ought not be a problem with the regulation in the M1-ATX. Go for it!
                  Originally posted by ghettocruzer
                  I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
                  Want to:
                  -Find out about the new iBug iPad install?
                  -Find out about carPC's in just 5 minutes? View the Car PC 101 video

                  Comment


                  • #10
                    Originally posted by Bugbyte
                    It helps keep the power dropping BELOW 12 volts. But you can still get spikes above. But that ought not be a problem with the regulation in the M1-ATX. Go for it!
                    ok, def. going with the m1-ATX, one last question, i already have this battery, the one mentioned above from the UPS, are there any benefits, or anything good if used it? i jus had this battery, dint want it to go to waste.

                    Comment


                    • #11
                      Hi pr3d.

                      You are on the right track with your circuit. Just place the diode on the positive line and make sure the cathode (the side with line on a diode schematic) faces towards your backup battery. One other thing, make sure you have a diode that is rated for the type of current you are going to need. I would recommend no less than a 20A rated diode. Remember that when diodes are rated, they take into account that a great big honkin heatsink is attached to them.

                      Hope that helped. Good luck.

                      Comment


                      • #12
                        That setup with diodes on definely works. I have used that same setup with a 9Ahr battery, for a month without any problem. But now i have a different setup since i am worrying about forgot to turn off the inverter and the main battery will go dead. Rather than putting a diodes in between two batteries, I use a relay. The relay is tapped to accessory 12+. In case someone doesn't know, the purpose of accessory wire is to cut off the power to radio, amp and other miscellaneous device so starter motor get all the current to crank the engine. In other word, the power is cut between main battery and small battery when it is during cranking state. This way, computer is running from small battery for few second. After you release the ignition key, the accessory get 12+ again, and your relay connected the main battery and small battery. But keep in mind, don't use too small wire connecting all the device. When your computer run off the main battery, once your small battery is drained. The next time you put your key in, you are charging up the battery with infiniti current as well as powering up your computer, so your small wire will get hot might result in fire. My 10A fuse almost melt, so don't run off your small battery from main battery for too long, unless you use all big thick wires...
                        2006 Camry
                        Compaq Laptop
                        Holux GPS Iguidance 3.0
                        7" Xenarc Touch Screen
                        Carnetix 1900 Power Supplied, Wireless b/g

                        Comment


                        • #13
                          Yep, thats the exact circuit I have been using for about 2 months now, battery out of a UPS & works great. Just tied about 4 6A diodes in paralell from a local electronics shop, one by itself got pretty warm so spread the load a bit.

                          Mine is on the positive line though
                          Semperon 3200+/512MB/ Seagate SATA2 120GB
                          10.2" Xenarc/ Netgear USB Wireless
                          M2-ATX/RadioShark
                          BU-353 GPS Receiver

                          http://www.happyg.mine.nu/carpc/index.html

                          Comment


                          • #14
                            You are better off putting the diode on the positive line.

                            I would also suggest the relay idea, especially if you plan on running the computer when the engine is off, this will prevent a dead main battery.

                            If you do plan on doing this you may need even more than 20A rating on the diode.

                            W/O knowing how efficient the DC-DC power supply you have is, you are pulling in the neighborhood of 90 watts / 12v = 7.5Amps for the power supply assuming it were 100% efficient and only supplying 12v. If you run the backup battery down and need to charge it, then that battery becomes a load instead of a supply, and will add current consumption to your power supply. 20A is probably enough, but always better safe than sorry. Also, make sure you have a fuse very close to the main battery on the lead going to the second battery, and another fuse close to the second battery. This way if the cable shorts you won't blow up the battery or start your car on fire. If the fuses are the same rating as your total diode that would also protect the diodes in the event of an over current draw.

                            Comment


                            • #15
                              I think KyferEz got me started on low voltage drop doides. I got this one at Mouser:
                              http://www.st.com/stonline/books/pdf/docs/5512.pdf
                              Have only tried charging a battery with it so far and didn't see much drop, but did notice as the battery reached capacity the voltage drop decreased to 0.

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