Battery not holding/getting charge

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  • MNE30
    Member
    • Jan 2013
    • 79

    #1

    Battery not holding/getting charge

    I've figured out whats wrong with my car after charging the battery twice. The battery isn't getting charged so after about 2 minutes of running it dies, I've decided that it's probably my alternator, but could there be another cause? A bad ground perhaps? I'm not too good with the electric side of things on cars so I'm stumped, any input would be nice.

    Also how should I go about testing my alternator with a multimeter?
  • jlevie
    R3V OG
    • Nov 2006
    • 13530

    #2
    A fully charged battery in good condition will run the car for a lot longer than 2 minutes.

    The first check is to make sure that the battery light in the cluster comes on when the ignition is turned on. Except for late production cars, that bulb is the source of exciter power for the alternator, without which it won't charge.

    If the alternator is working properly and the battery is good and fully charged, system voltage will ~13.5v at idle rising to ~14 at 2500rpm. Those voltages should not significantly change when load is added (headlights on high, blower to max). If the alternator bearings are good, in most cases all that is needed is a new voltage regulator.

    Other than the battery connections, the next most important ground is the one that goes from the left side of the engine to the chassis.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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    • MNE30
      Member
      • Jan 2013
      • 79

      #3
      Originally posted by jlevie
      A fully charged battery in good condition will run the car for a lot longer than 2 minutes.

      The first check is to make sure that the battery light in the cluster comes on when the ignition is turned on. Except for late production cars, that bulb is the source of exciter power for the alternator, without which it won't charge.

      If the alternator is working properly and the battery is good and fully charged, system voltage will ~13.5v at idle rising to ~14 at 2500rpm. Those voltages should not significantly change when load is added (headlights on high, blower to max). If the alternator bearings are good, in most cases all that is needed is a new voltage regulator.

      Other than the battery connections, the next most important ground is the one that goes from the left side of the engine to the chassis.
      I can check those when I get home, and as in left side you mean drivers side?

      I checked the ground from the oil pan to the frame rail and it looked good.

      Comment

      • EatsHondas
        E30 Addict
        • Sep 2012
        • 404

        #4
        Originally posted by MNE30
        I checked the ground from the oil pan to the frame rail and it looked good.
        Yeah, that's the same ground. There should also be a ground on your passenger-side shock tower. I don't know if it's part of the charging circuit, but it never hurts to make sure it's clean, tight, and undamaged.
        1989 325i Lachssilber Sedan
        5-Speed Swapped
        M30B35 Swapped
        MegaSquirt MS3X

        1987 325i Lachssilber Sedan
        260k OEM Automatic Daily Baby

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        • MNE30
          Member
          • Jan 2013
          • 79

          #5
          Originally posted by EatsHondas
          Yeah, that's the same ground. There should also be a ground on your passenger-side shock tower. I don't know if it's part of the charging circuit, but it never hurts to make sure it's clean, tight, and undamaged.
          I am slowly fixing all my problems and now I'm on to the next, I got the grounds all cleaned and fixing my alternator, some bad leads on the back and it was just in need of some TLC (works, for now).

          Now I've got to figure out if it is misfiring or not, I can't really tell.

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