3 liter V6 drains 10 amps at rest, no smoke.

Discussion in 'General Motoring' started by mm, Mar 23, 2009.

  1. mm

    mm Guest

    My '95 leBaron with a 3.0 liter engine has a problem new to me.

    The charger shows 12 amps going into the car, even when the battery is
    disconnected, the ignition is off, the key is out, but nothing is

    Where is all the current going?

    When the charger is connected, and the battery isn't, the door locks
    work slowly and when I turn it on, the radio lights up but barely.

    The car was running fine when I parked it last.

    To start from the beginning:
    The battery was dead in the morning, after not using the car
    yesterday. I hooked up the charger and it was putting more than 12
    amps into the car/battery, but the battery car got no closer to
    starting the car. Totally dead. (I don't see how the battery could be
    the problem but for the record, I disconnected the + cable to the
    starter, and the battery showed 5 volts but would barely accept
    anything from the charger. But that increased to 6 amps and the
    battery was over 12.2 in a few minutes when I had to stop.)

    The resistance of the whole car, not including the battery, is 40
    ohms. Darn, I forgot to measure it in the other direction.)

    What should I do next?

    P.S. I have the strange feeling that I need to hit the starter motor
    with a hammer.

    Thanks for any help you can give.
    mm, Mar 23, 2009
  2. mm

    Bill Putney Guest

    Here are sxome things to try:

    Disconnect one or more circuits to isolate the problem (pull fuses or
    unplug things or whatever - do you have the vehicle schematics?) - IOW -
    disconnect everything from the main bus - you should have almost zero
    current draw from your charger with that. Then connect a circuit at a
    time until you get the high current draw again. That will tell you which
    circuit has the short.

    It sounds like the battery is fried due to being severely drained
    possibly as a result of the original problem (a short). So now you have
    two problems - a short and a boat anchor battery.

    What is the current rating of the charger you are using?

    When you have the battery disconnected and you hook up the charger to
    the car (not the battery), what voltage do you measure?

    The charger is going to put out its programed limit of current even if
    there's a dead short to ground in the car's main power bus - and that
    could very well be what you are seeing.

    The 40 ohms you are reading may not mean anything because the meter
    doesn't try to force a very high voltage onto the wires to make that
    reading. It may be a non-resistive short. You may have something
    shorting out above, say 3 volts. I think the voltage reading with your
    charger hooked up without the battery will tell part of the story.

    SUMMARY: (1) Isolate the circuits to see which one is shorted. (2)
    Measure the voltage at the charger output when it is connected to the
    bus with the battery disconnected.
    Bill Putney, Mar 23, 2009
  3. mm

    Bill Putney Guest

    Also - a test light (get it at you local auto parts store) may help in
    the isolation of the circuits to find out which one is shorted. With
    main fuses pulled, put voltage to the bus, then bridge the fuse holders
    one at a time to see which one lights the light - thats the circuit with
    the short.
    Bill Putney, Mar 23, 2009
  4. mm

    Steve B. Guest

    It isn't a good idea to connect a charger to the car with no battery
    in place. Electronics like clean even power. When you hook the
    battery charger directly to the car with no battery you loose the
    inherent filtering capacity of the battery and battery chargers put
    out particularly nasty power because there is normally no need to
    filter their output.

    Basically having the car on a charger with no battery will cause the
    electronics to go nucking futs and anything is likely to be happening.
    A battery that was at 5V did not charge back up in a couple of
    minutes. I would recommend that you fully charge the battery and have
    it load tested then put it back in the car. Give the system a little
    time for the computers to do what they need to do and see what the
    power draw is.

    My hunch is that you have a battery that has croaked and once you
    replace it things will return to normal. I could very well be wrong
    though... make sure you test the actual current draw with the battery
    in the vehicle to see what's goin on.

    Steve B.
    Steve B., Mar 24, 2009
  5. mm

    Bill Putney Guest

    You are correct about the filtering that a battery provides in the
    electrical system. But that still doesn't explain the 12 amps that the
    vehicle is drawing from the charger. Something is presenting a
    conductive path to ground for it to be pulling 12 amps with everything off.

    I agree that the battery needs to be working (the one he has is probably
    toast due to being totally depleted and left that way for a time), but
    there is something that is pulling current - in other words, a short.
    Bill Putney, Mar 24, 2009
  6. mm

    Olaf Fub Guest

    Internal short within the battery due to failure of one or
    more cells - mechanical failure vs chemical failure.
    Olaf Fub, Mar 24, 2009
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