Results 1 to 8 of 8

Thread: Alternator output voltage

  1. #1

    Alternator output voltage

    Does anyone have the output specs for the Bosch alternator with built in regulator???
    Ed Barnett
    RGruppe #124
    Northern California Racing Club
    American Racing Club
    Member, Northwest Hillclimb Association

  2. #2
    It should be about 13.6 to 14.2 volts

  3. #3
    Thanks Rick...I'm at 14.1 so within spec.
    Ed Barnett
    RGruppe #124
    Northern California Racing Club
    American Racing Club
    Member, Northwest Hillclimb Association

  4. #4
    I use this old post to ask a question…

    Just installed a rebuild SEV Marchal alternator in my 2.0 911E with an external regulateur
    At idle I have 13.65V, but when I rev 2500 rpm or more I have a little bit less around 13.55V.

    Since this alternator is under warranty I’m wondering if this is a normal behavior ?


  5. #5
    Yes, that's okay, it's one volt more than battery voltage.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  6. #6
    I have one more question, is it normal the output voltage drops under load ?
    If I put everything on I read less than 13V…
    The regulator is new.

    Still trying to decide if I need to send back my rebuild alternator to the shop ?

  7. #7
    An alternator can put out 18 or more volts, that's why you have a voltage regulator, I would send alternator AND regulator and if regulator is adjustable they can set it to a higher voltage. You should have 13 volts or slightly more under load. If regulator is non-adjustable and the rebuild shop supplied it maybe they can try another. Originally the regulators were all adjustable,,,then we got the cheaper solid state ones. As long as charging voltage is greater than battery voltage it should charge the battery, but at less than 13v. you're getting on the ragged edge. If the units bench test higher then you have resistances in your wiring.
    Early S Registry member #90
    R Gruppe member #138
    Fort Worth Tx.

  8. #8
    ^^^^ Yet another concise and informative description. Ed, I always appreciate your helpfulness.
    Peter Kane

    '72 911S Targa
    Message Board Co-Moderator - Early 911S Registry #100

Similar Threads

  1. Replies: 11
    Last Post: 09-15-2013, 04:28 AM
  2. charging issue...alternator or voltage regulator
    By cmcfaul in forum Technical Info
    Replies: 1
    Last Post: 08-18-2013, 04:56 AM
  3. Replies: 12
    Last Post: 06-16-2013, 05:07 PM
  4. WTB: G50 Output Flanges
    By Mr9146 in forum For Sale/Wanted: Other Porsche Cars and Parts
    Replies: 0
    Last Post: 01-26-2012, 10:49 PM
  5. Alternator or Voltage reg? 73.5T
    By mike walker in forum Technical Info
    Replies: 5
    Last Post: 07-08-2007, 05:09 AM

Posting Permissions

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

Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.