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  • Negative Voltage????

    I just bought this power supply: http://www.orbitmicro.com/products/p...2/KPDX250H.htm

    Its inputs are GND, +, -. I know how to get the ground and positive, but what on earth do I do for the negative???

  • #2
    just connect the negative to your cars chassis, you shouldnt have to worry about GND
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    • #3
      Can you tell me if that psu works out alright, in my opinion the description looks perfect, power wise. Tell me how it works out.

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      • #4
        That thing is 250 watt at 60% efficiency = 150 watts. Opus does that, has a built in shutdown controller, and is smaller. Sounds like a waste of money to me. For $15 more dollars, get the Opus.
        7" Lilli TS, Soyo K7VME, Semperon 2200, 160GB Maxtor, 512mb PC3200, Deluo GPS, Panasonic Slim DVD/CD RW, Linksys WMP545G , Opus 150w, XMDirect, XP Pro, FP, IG [XXXXXXXXX-] 90%
        ATVMS.com

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        • #5
          Originally posted by sfay93
          That thing is 250 watt at 60% efficiency = 150 watts. Opus does that, has a built in shutdown controller, and is smaller. Sounds like a waste of money to me. For $15 more dollars, get the Opus.
          power supplys are rated (well supposed to be rated) at their output power not their input power, remember that the opus is about 90% efficient
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          • #6
            Originally posted by sfay93
            That thing is 250 watt at 60% efficiency = 150 watts. Opus does that, has a built in shutdown controller, and is smaller. Sounds like a waste of money to me. For $15 more dollars, get the Opus.
            Its 60% efficient meaning it uses 417 watts and outputs 250. Whereas the Opus only outputs 150.

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            • #7
              I got one of those about 3 years ago and have been running it with no problems on a Celery 300 system. It still works, so I'm going to be using it in a new machine with a Celeron D 330. I've done short tests on a garden tractor battery and it seems to work fine.

              I just use the + and - terminals. Use an amp cable (~4 ga?) run from the battery to + and a cooresponding cable from - to the car chassis.

              The only problems I have is that it's Full Size ATX - big sucker. And the power cables are simply too long. It's set up for use in tower cases - I'll be using many twist ties to clean up the excess!

              It does have 250W output. Compare the numbers:
              V / Keypower / Opus 150
              +5 / 25A / 10A
              +3.3 / 14A / 10A
              +12 / 10A / 5A
              -5 / 1A / ?
              -12 / 2A / .2A
              +5SB / 1A / 1A
              http://www.jeepmp3.com/
              CarPC Stolen. Starting over.
              Ne1 recognize the avatar?

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              • #8
                Opus: ">89% at optimum loads"

                KeyPower: "60% at typical load"

                I bet their efficiencies are pretty close to each other.

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                • #9
                  Hey eCar (or anybody else with this power supply), does it survive cranking for you. I got it working and hooked up (pictures of my setup to come shortly), but the computer reboots on cranking. I haven't installed the shutdown controller (from mp3car.com) yet, I dunno if that will affect it or not.

                  It might also be affected because I have 18awg wire running into the +/-/gnd terminals, I have 4awg running from battery/ground to trunk, then I just spliced it into some 18awg cuz the 4awg was too big for the terminals on the PSU.

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                  • #10
                    Originally posted by Optikal
                    Hey eCar (or anybody else with this power supply), does it survive cranking for you.
                    Are you talking about the Keypower? Nope - my old machine never survived cranking. Might have been the battery, but I'm guessing it may have been something else. That machine didn't use 4ga wire, though - I think it had 10.

                    Keypower's were pretty popular a few years back, and (if memory serves) some people were successful with it during cranking. Do a search and you might find something.
                    http://www.jeepmp3.com/
                    CarPC Stolen. Starting over.
                    Ne1 recognize the avatar?

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