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Thread: charging voltage

  1. #51
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    Maybe it's time to start again before you have a stroke (and not the fun kind).

  2. #52
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    Quote Originally Posted by ross1 View Post
    OP has never said the battery wasn't being charged.
    yes well sorry about not mentioning that. battery isn't being fully charged, ever. driving the car for a couple weeks is enough to drain it (my work is 20 miles away from my home so the distance is enough for topping it up after starting) and there is no parasitic drain (tested it)

    it never gets depleted but think of it like half charged all the time. everytime I connect an external (smart) charger, battery takes about 20-30ah in it. it's definitely not being charged adequately by the car.

    I already said I observed the charging voltage on my friend's e38 and it was fine, operating @ constant 14v. if you don't believe that, jimlev here also said his charging voltage is not dropping like mine so there is your proof.
    Last edited by TiesTorN; 02-26-2021 at 05:00 AM.

  3. #53
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    Quote Originally Posted by cv auto View Post
    Read voltage after testing. You should see a drop off of .5-1.5Volts during the test and a slow rise back to 12.5V+ on a completely healthy
    battery is healthy it's 1 month old. there was no need but had it tested anyway. passed with flying colors.

  4. #54
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    If your battery test passed with flying colors (what does that mean?) then one would assume it is getting fully charged, right?
    Was it load tested with an adequate load?
    Have you checked for corrosion on the places we discussed earlier?

  5. #55
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    "Details details. We don't need no stinking details"....

    (You have a personal editor too, LOL)

    Hey, I liked the beating a dead horse images!
    Last edited by StephenVA; 02-26-2021 at 10:27 AM.
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  6. #56
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    Quote Originally Posted by JimLev View Post
    If your battery test passed with flying colors (what does that mean?) then one would assume it is getting fully charged, right?
    nope... I charged it with my smart charger before being tested

    lol.. flying colors means the test equipment (analog gauge) showed higher end of the "green" area... load was 300a if I'm not mistaken.

  7. #57
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    That test says the battery is good!

    I would look at wiring, ground issues as that is all that is left. (check the wiring plug to the alt for pin alignments and corrosion, as JimLev mentioned)
    Last edited by StephenVA; 02-26-2021 at 10:28 AM.
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  8. #58
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    yep I will do that, haven't had the chance yet.

  9. #59
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    No problems, You are doing fine chasing a electrical issue. When you test and eliminate components, what is left, is where the issue/problem lies. It is just a simple case of narrowing down all the issues. I would also take a look at the lower engine grounds to confirm they are there and doing their jobs. At a 100K/160KM who knows what was kicked up off the road and what it hit.
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  10. #60
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    It's good you load tested the battery - just being "one month old" doesn't guarantee it's good. Could've had a bad cell. But know you know for sure, rather than guessing/assuming, that it's OK and can move on to other areas.

    What if you use a jumper cable and run a ground directly from the battery to somewhere on the engine. Would that help to point you in the right direction? Meaning, if things then work normally, it pretty much guarantees there's a ground issue? And/or run another temporary ground from engine to frame?

  11. #61
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    Quote Originally Posted by DennisG01 View Post
    It's good you load tested the battery - just being "one month old" doesn't guarantee it's good. Could've had a bad cell. But know you know for sure, rather than guessing/assuming, that it's OK and can move on to other areas.

    What if you use a jumper cable and run a ground directly from the battery to somewhere on the engine. Would that help to point you in the right direction? Meaning, if things then work normally, it pretty much guarantees there's a ground issue? And/or run another temporary ground from engine to frame?
    +1
    the 12V+ connection at the bottom of the cowl is exposed and subject to corrosion as well.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  12. #62
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    Hi guys,
    Sorry for intruding,
    Just would like to share my recent experience and if it's somehow helpful, that's good enough for me,
    Had the same mind riddle that is described here and would never find out about it if not due to; a "cigarette lighter voltmeter"
    Yes, thanks to the cigarette lighter voltmeter I watched in horror the system voltage dropping to 12,0V during acceleration and raising to 14,7V during downhill "coasting"... (Normal Operation by the way)
    Is it the Alternator? the voltage regulator? the IBS cable? what is it?
    Took my X6 E71 35d to a BMW dealer that suggested to start by an alternator change... (around 700€)
    Then a couple of indy mechanics; one opened up the alternator, saw nothing wrong with it and change the voltage regulator and bearings (120€); the other suggested swapping the battery IBS cable (290€)....
    Before all this, everything was working normally and it would had stayed that way if I hadn't buy that cigarette lighter voltmeter,
    Instead of trying to explain why is this how the system operates, I attach the BMW service manual that describes it in detail,
    Thanks for reading it, Great forum,
    intelligent alternator regulation.png

  13. #63
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    You do realize that the technology has been around for years, but unfortunately BMW did not use it in X5 E53 or E39 applications on any engine size that I am aware of. The article you quoted is for three or is four generations newer X6. Any tech should have known about hard acceleration charging system cut out, as it was all over the technical articles when BMW started using it to free up HP.

    The unintentional consequences of this technology along with auto start/stop feature, is a very short lifespan of batteries and starters. But we are saving the planet don't you know so everything is only measured in miles per gal and tail pipe emissions outputs. Battery in the junk yard, no one measures that output...
    Last edited by StephenVA; 03-09-2021 at 11:17 AM.
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  14. #64
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    Interesting, I'd not heard of that before. Now I know disconnecting the A/C compressor at WOT has been done on some cars for decades, but the alternator? Not the start stop, but I guess if done right it makes sense, kind of a hybrid like charging, albeit not off braking but just coasting. New cars are so far removing from any kind of KISS philisophy, more the engineers creed of "if it still works it's not complicated enough yet" state of mind.
    98 328is
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    and decades of owning and driving BMWs

  15. #65
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    Quote Originally Posted by Tonivegeta View Post
    this is plain bs. you could drive for an hour and still not coast. battery would be dead by then.

  16. #66
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    ok... lifted the car yesterday and cleaned every contact & connector. they were in a bad shape. also disassembled the fuse box in the trunk (above battery) and cleaned every contact point. it was a white mess. and also connected an extra ground cable on the engine block.

    result? nothing has changed... sigh...

  17. #67
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    Under the passenger seat electric connectors are next? Once wet they will corrode away to dust. Theyhave some very large wiring connection jump and split points under the carpet and seat. Always a source of wacko electrical issues if compromised.
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  18. #68
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    Quote Originally Posted by JimLev View Post
    Ties, we posted at the same time, see post 14.

    Also did you know the battery cable under the car is spliced to the cable that runs to the alternator? It’s by the rear pass side of the engine subframe.
    Did you check the splice we spoke about?

  19. #69
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    Quote Originally Posted by StephenVA View Post
    Under the passenger seat electric connectors are next? Once wet they will corrode away to dust. Theyhave some very large wiring connection jump and split points under the carpet and seat. Always a source of wacko electrical issues if compromised.
    yes that is next. though I feel too lazy for that...

    Quote Originally Posted by JimLev View Post
    Did you check the splice we spoke about?
    couldn't find that

  20. #70
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    On the back side of the subframe there is a cable that is clipped on, pretty easy to see.
    The splice is on the pass side, one side goes to the starter, the other goes to the alternator.

  21. #71
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    Quote Originally Posted by JimLev View Post
    On the back side of the subframe there is a cable that is clipped on, pretty easy to see.
    The splice is on the pass side, one side goes to the starter, the other goes to the alternator.
    you mean behind the front subframe right..? yeah I saw that. looked clean. also looked like it can not be disassembled so didn't touch it.

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    Just because it looks clean, doesn’t mean that the contact points are clean.
    Set the controls for the heart of the sun

  23. #73
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    Quote Originally Posted by TiesTorN View Post
    you mean behind the front subframe right..? yeah I saw that. looked clean. also looked like it can not be disassembled so didn't touch it.
    Yes. The outside may be clean but you have no idea what the inside looks like unless you open it up. As an alternative you could get some long meter leads to connect one end to the battery and the other to the alternator and then to the starter to measure the voltage drop. That will show you if you have a bad connection.

  24. #74
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    seemed like there was no way of opening it up without tearing the outer shell.

    afaik that is a one piece wire to the battery, which splices(inside the shell) into the starter so it means the starter may get a weak connection but battery wouldn't. am I wrong? (starter is getting good connection btw, cranks very fast)
    Last edited by TiesTorN; 03-13-2021 at 01:00 AM.

  25. #75
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    volt drop
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