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Stupid question of the day. Parasitic draw.

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Selahdoor, Aug 3, 2019.

  1. DaveBen

    DaveBen Supporting Member Supporting Member

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    You can just remove the fuse and test. A blown fuse is NOT needed to test.
     
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  2. onetonjohn

    onetonjohn Full Access Member

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    Agreed you definitely don't need to use a fuse. I can see better getting the contacts extended.
     
  3. tradergem

    tradergem Full Access Member

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    I had a parasitic draw on my 90 f250 with E4OD that turned out to be the relay on the driver's side of the engine bay that turns on the power to the trans when they key is turned on. Since the relay gets power directly from the ignition relay always hot side there is no fuse for it to test. The relay was sticking in the on position and draining the batteries.
    I found this by hooking up my meter between the positive post on the passenger side battery ( the driver's side battery was completely disconnected ) and connecting one at a time to each of the wires that went to the always hot side of the ignition relay on the fender wall. Hope this helps.
    James
     
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  4. Macrobb

    Macrobb Full Access Member

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    9ma.... sounds like a radio keep alive memory?
     
  5. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    I'll be doing the test again.

    The priority right now, while I have the weather to do so, is to get the circuits built, that I need to build.

    Then get the truck actually running again, and get it on the road.

    Then remove the wiper motor to see if I can R&R it to make it work.

    In the meantime, I will just be taking the negative cables off the batteries, when I park it.
     
  6. YJMike92

    YJMike92 Full Access Member

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    9 milliamp is way good and will not be a problem.
     
  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    If one or both batteries still get discharged, then you'll know that you have a bad battery or two.
     
  8. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    I should have added that it was still on it's way up, when I pulled the leads.

    I was just doing a quick check, out of curiosity.

    Maybe I'll do it again today, and see how high it eventually goes.

    I've got other things to get done first, though. Including a trip to town.
     
  9. chillman88

    chillman88 Supporting Member Supporting Member

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    If you can't let me know. I might have one kicking around I pulled off a parts truck if you need it.

    What's wrong with it, what's it doing?
     
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  10. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    Totally corroded. Not doing anything at all when I turn it on.

    I haven't really looked into it yet. I'd assume the linkages are corroded and need to be broken loose and lubed.

    Then the motor looks like it's probably full of corrosion.

    I'll get to it in it's time... :D Couple other "eventually's" have to get their turn, first. LOL
     
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  11. ClifFord

    ClifFord Registered User

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    Great technical comments guys. I'm learning alot on here. Also some dummy comments from me. I recently discovered that my negatives were really corroded. I replaced with 0gage and cleaned all the grounding points with a wire brush and connected everything back up. Also used big wire on the big 3. Both batteries to frame, alt to frame, and block to frame. Solid power now. No flicker or random arcs.

    Sent from my cp3705A using Tapatalk
     
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  12. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Sometimes the easy things can give amazing results.
     
  13. Selahdoor

    Selahdoor Supporting Member Supporting Member

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    Inside for a break.

    Clamped the leads to the post and the cable end, and just left it there.

    Climbed quickly past 9 milliamps. Then started climbing slower and slower from there.

    The slowdown was progressive.

    After almost ten minutes it was up to 17.53, and all but stopped there.

    That's the amp draw test...

    Edit: Up to 19.53 and seemingly pretty much stopped there, after 45 minutes. Pulled the leads. End of test.

    Will continue with the other tests, later.
     
    Last edited: Aug 14, 2019
  14. BeastMaster

    BeastMaster Full Access Member

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    You didn't forget to unplug any new high tech add-on goodies?

    Any heavy loads on, but powered through a bad connection that keeps you from seeing it?

    I'm thinking something like a bad brake switch that's not going completely open.

    Or maybe some conductive crud around a terminal somewhere that shunts to ground when wet?

    I can't think of anything that has that current draw profile you describe. Wish I could listen to it...using a transformer to get the DC out of it. Corrosion and bad connections are quite hissy.

    It will take several months for 20ma to drain your battery. Maybe it gets far worse when wet? 20 ma does not bother me all that much, but the fact it changes does.

    I remember well how long it took me to trace down a problem in my PSOM that made my transmission act up.

    This is the kind of problem that can drive you nuts. Intermittent problems. Keep at it. It's in one of the loads. Divide and conquer.
     

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