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    This a Good Test for Electrical Shorts?

    GO TO POST #19 FOR THE HOW-TO. For the story of the shade-tree mechanic w/o a clue , read all the posts!
    http://www.r3vlimited.com/board/show...9&postcount=19

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    The Bentley manual says to detach the battery ground cable and attached a test light between the negative terminal and the now detached ground cable. If the test light is on, then you have a parasitic draw.

    I did this test, and I pulled every fuse and relay one-by-one. The light stayed on. Then I detached the wires from the starter and the alternator. Light stayed on. The only thing left to try is to remove the gauge cluster.

    Before I go to all that trouble, I just want to check to see if anyone else has had luck tracking down a drain with this method.

    I've got some kind of strange draw that allows me to start the car OK even after 2 days of not driving it. But after about 4 days, the battery is so dead that when I hook up my trickle charger, it doesn't even recognize that it's attached to the battery. If I leave the charger connected, the battery does fully charge up overnight. I've driven the car for long road trips without any electrical issues. The AAA guy hooked up his tester to the car, and he showed no drain on the battery with the car shut off.
    Last edited by Aleman; 11-03-2013, 01:08 PM.
    R135 /// 1990 Alpinweiß II 325is
    └┼┼┘ /// 1993 Black/Black Convertible (sold)
    ..24

    #2
    That test will work if and only if the test light requires more than 60ma to light. The better way is to use a DMM and actually measure the current flow.

    In the stock configuration everything in the car except the DME, alternator, and ignition switch are fused. So if you don't find the cause of the excessive parasitic draw by pulling fuses and/or disconnecting the alternator, that leaves the DME or aftermarket electronics as the problem.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

    Comment


      #3
      Thanks Jim, your advice is always great! I checked the test light, and it says 200m on the label. I went ahead and switched over to the multi-meter anyway to get a more precise measure. As I went thru pulling fuses and relays, disconnecting the alternator, starter motor and DME, there was no significant change in the reading. It always stayed in the 11.8 to 12.5 range, and connecting the MM repeatedly would usually give a small variance in the readings too (+/- 0.3). What is considered a good reading - when there is no drain?

      Am I looking for the number to drop when I've pulled the right fuse? Sometimes the reading went UP a little when I pulled a fuse. Do I have this MM set correctly? None of the other "200" settings gave a reading, so I assume...

      R135 /// 1990 Alpinweiß II 325is
      └┼┼┘ /// 1993 Black/Black Convertible (sold)
      ..24

      Comment


        #4
        That picture shows the meter set to read voltage, not current. Check the meter's instruction manual to verify, but to measure current it looks to me like the red lead needs to b plugged into the left hand hole an the dial turned to the right to lower 200m setting.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

        Comment


          #5
          Leave the leads where they are. You only need to move them if measuring in the 10A mode.

          But yes, you need to turn the know around to about the 3-4 o'clock position where it says "200m". The very bottom red box. The one above that is for AC amperage.

          Comment


            #6
            Originally posted by NitroRustlerDriver View Post
            Leave the leads where they are. You only need to move them if measuring in the 10A mode.

            But yes, you need to turn the know around to about the 3-4 o'clock position where it says "200m". The very bottom red box. The one above that is for AC amperage.
            Good catch, I didn't see the ma legend above the right hand socket the first time.
            The car makes it possible, but the driver makes it happen.
            Jim Levie, Huntsville, AL

            Comment


              #7
              Switch the red lead over to the socket that is labeled "10A"

              Then turn the meter knob to 10A "ADC" The 200MA scale is for milliamps with a maximum of 200mA, the battery and draw might pull more than 200 so its best to use the 10A scale.

              Make sure all the doors, ignition, and trunk lights and power are off. So you don't have a false reading. Pull the trunk light out if you have to.
              Owner - Bavarian Restoration
              BMW and European Electronics Repair and Restoration
              www.BavRest.com
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                #8
                Thanks for your patience guys. This will be a very useful how-to once we figure it out. I know I'm not the only one out there that is clueless about multi-meters & how to use them. I've only ever used them for testing ohms. So here is a clean shot of the face & label of my MM with no attachments:



                Originally posted by NitroRustlerDriver View Post
                Leave the leads where they are. You only need to move them if measuring in the 10A mode.

                But yes, you need to turn the know around to about the 3-4 o'clock position where it says "200m". The very bottom red box. The one above that is for AC amperage.
                I turned the knob to ADC 200m, and put the probes on the negative terminal and the grounding cable, but got a '0' reading:


                Originally posted by Gregs///M View Post
                Switch the red lead over to the socket that is labeled "10A"

                Then turn the meter knob to 10A "ADC" The 200MA scale is for milliamps with a maximum of 200mA, the battery and draw might pull more than 200 so its best to use the 10A scale.

                Make sure all the doors, ignition, and trunk lights and power are off. So you don't have a false reading. Pull the trunk light out if you have to.
                I pulled the trunk bulb a few days ago when I first starting tracking down the battery drain. I switched the red probe to the 10A plug and turned the knob to ADC 10A. Got '0' reading:


                and then just for fun I switched it to ADC 200m to see if I could get a reading at more sensitive setting, still '0':


                Does this mean I have no draw on the battery? To answer the obvious question - yes, my positive cable is attached to the positive terminal, and I haven't had detached for any of the tests so far. Thanks again gents!
                R135 /// 1990 Alpinweiß II 325is
                └┼┼┘ /// 1993 Black/Black Convertible (sold)
                ..24

                Comment


                  #9
                  10A is way too high of a draw for a car just sitting. Switch it to 200 mA mode and return the red lead back to the right female connection on the DMM. You use middle and left for 10A and middle and right for 200 mA (as it states on the dmm).
                  ส็็็็็็็็็็็็็็็็็็็็็็็็็
                  Originally posted by blunttech
                  I need you to exfoliate my ballsack
                  Build Thread?



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                    #10
                    The 10A scale won't show anything unless the current draw is at least 100ma. But you should get a reading on the 200ma scale if the meter is working. Many meters will have the current measuring scales fuse protected. If the meter was set to current measurement and then used as if the measure voltage the fuse will blow and disable current measurement. A check would be to connect one lead of a test light to battery and measure current from the other lead to the ground cable. If the test light illuminates you know that current is flowing and the meter should indicate the magnitude. If the fuse is blown the light won't illuminate.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

                    Comment


                      #11
                      Your current measurements through the voltage scale could have damaged the meter or blown its internal fuse. It would appear your meter no longer works on the amperage measurement settings. You should have at least 20mA draw, which is normal.
                      Owner - Bavarian Restoration
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                        #12
                        One thing...you technically have the probes "backwards". The red positive one should be on the chassis cable and the black negative one should be on the battery terminal. Most DMM's will show negative current values, but maybe this one doesn't.

                        It is highly unlikely that you damaged anything when set to volts since that mode has high impedance between the probes. You were just taking a voltage measurement in that mode, inadvertently.

                        Did you remember to put all the fuses and stuff back?

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                          #13
                          Originally posted by Gregs///M View Post
                          Your current measurements through the voltage scale could have damaged the meter or blown its internal fuse. It would appear your meter no longer works on the amperage measurement settings. You should have at least 20mA draw, which is normal.
                          Greg's right! I checked the multi meter for fuses, and it does have 2 of them, and the 10A fuse is blown. I'm going to replace that fuse & try again using his method described above. Check this thread in a few weeks if you care to see the results. I'm heading out of the country till July... Thanks for the heads-up Greg!
                          R135 /// 1990 Alpinweiß II 325is
                          └┼┼┘ /// 1993 Black/Black Convertible (sold)
                          ..24

                          Comment


                            #14
                            So I finally got a pair of new fuses into my multi-meter, and the draw on the battery seems to be too much for the 200m ADC setting. The fuse snapped right away when I tested the draw at that setting.

                            When I set it to the 10A ADC as pictured below (except I put the black on the terminal and red on the ground cable), I sometimes get an initial reading of up to 2.55, then it quickly drops down to 0.01. When I pull fuses from the main box under the hood in hopes of the read dropping to 0, the final reading sometimes rests at 0.02. Is my multi-meter hosed? Any idea why I'd get the spike when I first touch the contacts? I hit the terminals with some sand paper to ensure a good contact before doing these tests.

                            I don't know too much about electrics, so I'm confoozed here. Any idea would be greatly appreciated! Thanks!
                            R135 /// 1990 Alpinweiß II 325is
                            └┼┼┘ /// 1993 Black/Black Convertible (sold)
                            ..24

                            Comment


                              #15
                              First replace both of the fuses and only use the 10A scale. You should make sure your doors, interior lights, trunk lights are all off, especially the ignition.

                              Then measure amperage in the same fashion as the picture using only the 10A scale. A normal measurement should be around 20mA. Since you have a current draw, it will be higher. It should not matter which leads are connected to which poles.

                              In the picture, with a reading of zero, I would assume your fuse has blown again, you use a 1A fuse instead of a 10A fuse, or your meter is indeed damaged. GL
                              Owner - Bavarian Restoration
                              BMW and European Electronics Repair and Restoration
                              www.BavRest.com
                              My Feedback Thread
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