Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: Fluctuating voltage

  1. #11
    Join Date
    Apr 2013
    Posts
    125

    Default

    At this point I'm thinking I just need to buy a new alternator and hope that fixes this. It's very frustrating right now as I can't drive the car at all. Any other thoughts anyone before I pull the trigger on that?
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

  2. #12
    Join Date
    Nov 2010
    Location
    New Jersey
    Posts
    231

    Default

    I’d say you found the problem after some methodical testing. New alternator time.
    1985 Caterham Super Seven
    1952 MG TD
    1991 Lotus Elan
    2017 MX5 RF
    2018 Audi A5 Sportback
    2014 BMW X1

  3. #13
    Join Date
    Jun 2013
    Location
    N. California
    Posts
    102

    Default

    If you're actually getting a voltage drop of over .5V in the alternator wire to the battery you should check that wire very carefully. Since you said that your meter was hard to read at that point and that the drop appeared to go away, maybe you're at the meters limits? I'd borrow a meter .

    It does sound like the alternator is toast if you're getting just a bit over 12V at the battery. I had one work fine cold and fail hot. It was irritating to diagnose, but sounds like you're nearly there.

  4. #14
    Join Date
    Apr 2013
    Posts
    125

    Default

    Thanks for the input everyone. New alternator on order. Hopefully that fixes this. Will update once installed.
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

  5. #15
    Join Date
    Apr 2013
    Posts
    125

    Default

    New alternator installed. Drove maybe 25 miles today, in hot weather, and volt meter read as it should at idle and at speed. So it's fixed. Yay.

    Last year the tensioning bolt fell out of the alternator, and I got stranded with a dead battery. Based on what the sheet that came with the alternator said, my theory is that when the belt was slipping it fried the alternator - more likely the voltage regulator. But whatever, I'm good now.

    And - I was finally initiated as a true Seven owner today, when my wife and I got caught in a thunderstorm 2 miles from home. We saw the storm coming, but ran an errand on the way home anyway, as I liked the challenge of beating the storm. Definite Type 2 fun.
    1997 Caterham, BDA
    1991 Miata, supercharged
    2017 VW GTI

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •