Possible voltage drains

Discussion in 'Sparky's corner' started by Mart, Oct 14, 2019.

  1. Mart

    Mart Gold level member

    Got a slight draw with ign off. No clock, nothing direct to battery except MSD.
    Had 2 volts in battery this afternoon.
    Any ideas or possible causes?.
  2. flynbuick

    flynbuick Super Moderator Staff Member

    The battery itself is one.

    Use a clamp on amp meter at the battery. Then pull one fuse at a time to narrow down the odds to the circuit with the issue.

    Glove box and trunk lights can be the issue.
  3. Mart

    Mart Gold level member

    I'll pull those bulbs.
    The only thing that has pwr to operate with the ign off is the pwr seats.
    Can the MSD pull an amp or so just being connected?
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Not unless the box is on all the time. The small red wire connected to the ignition switch turns the box on.
  5. Dr. Roger

    Dr. Roger Stock enthusiast

    Maybe check the brake light switch.
  6. Mart

    Mart Gold level member

    I'll do some checking. I hate electrical glitches.......
  7. Waterboy

    Waterboy Well-Known Member

    A bad diode in the alternator can draw electric. It can kill a battery too. Ask me how I know.
    Mark Demko and Brett Slater like this.
  8. gstewart

    gstewart Well-Known Member

    trunk light?
  9. lemmy-67

    lemmy-67 Gold Level Contributor

    Dashboard ignition switches can short out over time. I've replaced the one in my 1980 Chevy van twice.
  10. Mart

    Mart Gold level member

    Popped out trunk & glove box lamps, no change. Unplugged alt & volt reg., no change.
    Test light glows intermittently. Brake light/ electric vacuum pump(it's wired in)switch and door jamb switches function ok. Pwr seat switch checks ok.
    MSD is disconnected, test light still does it's thing.

    Alt check puts out 16+ volts
    Still checking....
    Last edited: Oct 15, 2019
  11. Mart

    Mart Gold level member

    It's an on for 1 second and off for a second, slightly less than 1 volt draw. Weird
  12. flynbuick

    flynbuick Super Moderator Staff Member

    Current, not voltage, is drawn. Voltage is the electric potential between two points.

    Does it have flashers?
    1973gs likes this.
  13. Mart

    Mart Gold level member

    Current draw, yep.
    Emergency flashers, yes.
  14. flynbuick

    flynbuick Super Moderator Staff Member

    The reason I ask is you mentioned that your reading is changing at per second intervals and your emergency switch is likely tied directly to the battery through a flasher.
  15. 1973gs

    1973gs Well-Known Member

    Disconnect the negative battery cable and use an ammeter between the cable and the battery terminal. This will show you if you have a current draw. Using a test light or a volt meter means nothing. After you find out how many amps or milliamps current draw you have, remove one fuse at a time and see which one stops the draw. Don't open the door with the ammeter installed or you may let the smoke out of the meter depending on how many interior bulbs the car has. You will have to remove the fuse for the interior lights to prevent this.
    Electra man likes this.
  16. 1973gs

    1973gs Well-Known Member

    16 volts is too high. It will cook the battery
    Mark Demko likes this.
  17. Mart

    Mart Gold level member

    Cigarette/ courtesy fuse removal stopped draw.

    Last thing I used was the FAST A/F meter that has a cigarette plug in. That was last Wednesday. Must have started the drain then, cause the battery went down to 2 volts by 5 PM monday.
    The damn cheap plastic plug got hot and melted some. P.O.S.

    Now, I can't live without courtesy lights so I'll have to look into replacing the lighter socket itself or just disconnect power to it. Damn FAST cheapee plugs....:rolleyes:
    Steve Caruso said his plug melted also.
    Thanks for everyone's input.
  18. gstewart

    gstewart Well-Known Member

    I owned a 1981 Cutlass Supreme Brougham from new. About a year after purchase, the battery discharged. So I recharged it. Discharged it again. Recharged again. This time, I did as suggested above, remove the neg battery cable attached an amp meter between the cable & post and began removing fuses one by one. Problem was the power antenna which was pulsing extend itself from rest position. Cost of new unit was $125. I extended the antenna and disconnected the power source. Solved. I had the same thing about to happen on my 1991 Bonneville SSE only I heard the pulsing of the antenna and disconnected the power. Purchased new unit.
  19. pbr400

    pbr400 68GS400

    I had an ‘80 Regal that would occasionally kill its battery overnight. I was puzzled by the random nature of it until one evening I went outside and saw the ground lit up beneath the front end. Our driveway was steep enough that sometimes the angle at which it was parked would cause the underhood light to come on.

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