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Electrical - Using a DMM to check for parasitic draw on battery...???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Greg72, Nov 15, 2004.

  1. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I'm convinced that I've got a small electrical parasitic loss happening somewhere.

    Can someone explain the proper way to use my multimeter to measure the current being "stolen" from my battery while it's parked? I figure it's going to be a small number of milliamps, but once I can measure it I'll be able to start pulling fuses to quickly isolate which circuit is responsible for the draw and resolve the issue once and for all.

    /forums/images/graemlins/thumb.gif
     
  2. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    You Need to set the DMM to the Amps scale (usually 20A). Then disconnect the positive terminal of the battery, making sure you dont have the ignition or anything of a large amp draw on. Put one terminal of the meter on the battery, the other terminal on the positive cable end. You should have very little to no amp draw.

    Hope it helps,
    John
     
  3. Skigirl

    Skigirl 1/2 ton status

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    Shouldn't be more than a 20 milliamp draw IIRC. You can also use the meter with the negative terminal and cable. Make sure your doors are closed when you test.
     
  4. spearchucker

    spearchucker 1/2 ton status

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    Depending on how you have the positive cable hooked up to you stereo, it could be those huge capacitors you have. Since the battery has a small resistance the circuit would look like and RC circuit and draw some current.
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    No more stereo installed in the K5. At first, that's what I suspected....but even after removing all the stereo equipment, the problem persists....

    "Be sure to keep the doors closed".....HAHAHAHA that's a good one! SkiGirl must have one of them newfangled K5's with interior courtesy lighting!!!! No such luxuries exist on mine! /forums/images/graemlins/peace.gif
     
  6. K5 NUTT

    K5 NUTT 1/2 ton status

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    Had to do the same to mine last night. Just installed new optima and it was dead in three days. Turns out my stereo must be done as it had a 1.475 draw on it. I had a .055 after it was removed from the system.

    DW
     
  7. spearchucker

    spearchucker 1/2 ton status

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    [ QUOTE ]
    No more stereo installed in the K5.

    [/ QUOTE ]
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    Then you'll have to do what 83ZZ502_Jimmy posted and start pulling fuses. Post up when you find out what kind of current is being drawn.
     
  8. mrbill

    mrbill 1/2 ton status

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    [ QUOTE ]
    "Be sure to keep the doors closed".....HAHAHAHA that's a good one! SkiGirl must have one of them newfangled K5's with interior courtesy lighting!!!! No such luxuries exist on mine!

    [/ QUOTE ]
    So that means no under hood light? Had a draw on mine until I looked up and saw the light....
     
  9. barryb

    barryb Registered Member

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    you can do the same check at the fuse block on the circuit you pulled the fuse out of. Stereos and alarms get alot of blame, but are usually not the problem, Also check to see if the alternator is warm at all after the vehicle is off, when it should be cold - for it to drain your battery, the current has to be transformed to something - light, heat, etc.
     

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