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Pulling 2.5 A with everything off??

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  • Pulling 2.5 A with everything off??

    Okay, maybe I am just missing something here, but finally got all the hardware and software setup and am ready to re-install computer and all back into the car.

    For one final check I decided to make sure everything really shuts down when I shut down the system.

    I would explain how all the wiring is done, but I would exceed the post limit to do that.... Anyhow I kept unpulling things to see when the 2.5A draw stop... it never did.

    So I pulled the wires coming directly off the battery and probed them, it was still showing a 2.5A draw... Just wires?????

    Is that normal?

    Any thoughts you have would be most appreciated.

  • #2
    What kiind of car?
    2-2.5A isnt all that uncommon for newer cars when shut off.

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    • #3
      Originally posted by Iamthehor
      What kiind of car?
      2-2.5A isnt all that uncommon for newer cars when shut off.
      Well it is a 1984 Corvette, but that is not the issue... not in the car yet. The wire I was probing was a 12" RUN OF 12 gage wires from a test battery to my power header...

      But thanks for the thought....

      I wonder if it is just what the multimeter is pulling, but that wouldn't make sense either....

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      • #4
        try unplugging usb devices, if you have any connected.

        and the ammeter shouldn't be pulling anything.. A quick check though, did you switch that terminal when going into ammeter mode? I think a lot of those multimeters require you to do this.. been a long time since I've checked teh amps coming out of something though so I forget.

        And I know you said you can't really discuss your wiring cause it'd take too long, but you think you could give a really short description? It'd help.

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        • #5
          2.5 amps at the battery when everything is off? You've got a problem there for sure! At that rate, your battery will die within a day or two at the most.

          I think you need to give a brief description of your setup (hardware wise) and how it's wired. Also, describe exactly what you did to take your measurement.
          2004 4runner

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          • #6
            Originally posted by rando
            2.5 amps at the battery when everything is off? You've got a problem there for sure! At that rate, your battery will die within a day or two at the most.

            I think you need to give a brief description of your setup (hardware wise) and how it's wired. Also, describe exactly what you did to take your measurement.
            Note to self - dont try to be intelligent on the morning of jan 1.........

            my multimeter is autoranging - .2 - .25 amps is my normal draw w/o any extras hooked up

            2+ amps is bad in any case

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            • #7
              IMHO 250mA is also a bit high to keep your lead acid battery healthy.
              2004 4runner

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              • #8
                How are you testing this? The ammeter has to be in series with the circuit, not parallel. (you can't check amps like you can volts)
                Bruno Speech Recognition - Advanced Speech Recognition designed to control any program. Extra support for FrodoPlayer and Winamp.

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                • #9
                  Originally posted by rando
                  IMHO 250mA is also a bit high to keep your lead acid battery healthy.
                  when i worked at sears we would sometimes have to check for drains, and that seemed to be about normal for quite a few cars. especially considering that includes the light under the hood. mine gets cut in half with the light unplugged

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                  • #10
                    Pull out all the fuses until it stops, if you really want to know what it is. That might mess up the radio anti-theft thing though.

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                    • #11
                      don't forget guys, this thing isn't even in the car yet.. so a lot of that doesn't apply

                      what funkdamonk said is good advice. Doing it in parrallel you'd probably get a whole lot more than 2.5 amps though.. that's 12 volts over basically a short!

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                      • #12
                        Originally posted by FunkDaMonkMan
                        How are you testing this? The ammeter has to be in series with the circuit, not parallel. (you can't check amps like you can volts)
                        I think you might be onto something here FunkDa.....

                        System setup - (at the final step where I was still drawing 2.5 A)
                        1) A 12VDC Lawn Mower battery sitting on the kitchen counter.
                        2) 12" of 12 gage wire running off the Neg. terminal of the battery
                        3) 12" of 12 gage wire running off the Pos. terminal of the battery
                        4) A multimeter (set on auto-range) with a probe attached to each of the aforementioned wires.
                        5) A reading of 2.5 A on the multimeter....
                        6) Car 40 ft away in the garage
                        7) Computer 10 ft away on table

                        I think you got it FunkDa..... My bad

                        I have never really understood measuring amps, but I do remember something about you need something attached that is pulling a load (in series) to get to get an acurate reading.

                        Thanks much for the reality reminder

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                        • #13
                          Yah step 4 is where you went wrong. Current must flow through the meter for current readings. Think of current as water. It flows out your battery through the your power wire, into and through your circuit, and out the other power wire. To measure the flow through the entire circuit, pretend your meter is just an extension of your power wire. A current meter in a circuit is analogous to a wire.

                          By hooking the meter the way you did, you essentially shorted your battery through the meter. Either your meter has built-in overcurrent protection or your battery's EMF was unable to supply more than 2.5A. If you had had a voltage meter across the battery at the same time you probably would have seen a corresponding drop in voltage such that Vbattery = 2.5 * (internal resistence of your ammeter). Less expensive meters would have blown a fuse or been damaged.
                          2004 4runner

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