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  1. #1
    Join Date
    Jun 2013
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    Western NY
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    Default Starboard alternator over charged

    First time out since launch the starboard alternator was over charging @ 16+ volts. Returned to the dock checked all connections were tight, gauge was accurate. Restarted it several times, same problem. On the fourth start the charging rate was correct and for a couple more starts. I have a Charles in line digital charger. The batteries were fully charged (12.45 volts) when this happened. The charge rate was correct at idle but jumped to 16+ at 1,000 rpm.
    Engines are 2001 8.1 liter with 500 hours and 100 amp alternators.
    What could cause this, I don't want to replace the alternator at $800 nor do I want it to happen at an inopportune time.

  2. #2
    Join Date
    Jun 2006
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    Spotswood, NJ, USA
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    4,692

    Default Re: Starboard alternator over charged

    not being connected to the battery, causing the alt to run wild not seeing the "12v sense"
    bad internal regulator
    100A is overkill anyway
    Being a twin are you sure you actually have independant motors? sometimes both outputs are wired to a common isolator

  3. #3
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    Sep 2008
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    Default Re: Starboard alternator over charged

    Bad regulator would be my first guess....

    $800 - are you serious?? The MSRP I'm seeing is under $300 (crusader part) and the aftermarket units go for quite a bit less.....labor can't be that brutal - even under a fixed deck....

  4. #4
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by Bt Doctur View Post
    not being connected to the battery, causing the alt to run wild not seeing the "12v sense"
    bad internal regulator
    100A is overkill anyway
    Being a twin are you sure you actually have independant motors? sometimes both outputs are wired to a common isolator
    If the regulator is bad would it work and then not work? Has functioned well until now.
    100 amp, came with the boat.
    Motors are not connected except perhaps through the charger, but the port was charging properly.
    Last edited by slow cruiser; 06-11-2019 at 02:32 PM.

  5. #5
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    Western NY
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by makomark View Post
    Bad regulator would be my first guess....

    $800 - are you serious?? The MSRP I'm seeing is under $300 (crusader part) and the aftermarket units go for quite a bit less.....labor can't be that brutal - even under a fixed deck....
    The part number is RA097008, where is it listed for under $300, please.

  6. #6
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    Default Re: Starboard alternator over charged

    the number I got was RA097007, the 70 amp alternator. They list for ~ $275. Aftermarket ones are about half of that. And PCM buys them, they don't have unique source that makes them unique. As long as they are 'sealed' (for marine safety), they typically have a lebel with the SAE number on them.

    Like the Doctur said, 100 amps is way more than adequate.....I'd use the 70 amp one. If you are convinced you need the 100amp unit, I'd bet any decent alternator shop could upgrade a 70 amp unit and still save your hundreds....

  7. #7
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    Jun 2013
    Location
    Western NY
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by makomark View Post
    the number I got was RA097007, the 70 amp alternator. They list for ~ $275. Aftermarket ones are about half of that. And PCM buys them, they don't have unique source that makes them unique. As long as they are 'sealed' (for marine safety), they typically have a lebel with the SAE number on them.

    Like the Doctur said, 100 amps is way more than adequate.....I'd use the 70 amp one. If you are convinced you need the 100amp unit, I'd bet any decent alternator shop could upgrade a 70 amp unit and still save your hundreds....
    Thanks Mark, the 70 amp are common and less than $120. Would it be just a 'plug and play' or would I need to make any adjustments? As I said the 100 amps came with the boat, I have no idea why the original owner ordered them, paranoia perhaps.

  8. #8
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
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    10,885

    Default Re: Starboard alternator over charged

    Most all marine alternators cut back on the charge rate rather quickly.
    I agree....... 100 amp is over-kill.

    I'd also be willing to bet that the OEM harness is just barely heavy enough to effectively handle a continuous 100 amp charge rate.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  9. #9
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    Default Re: Starboard alternator over charged

    slow cruiser:

    From what I gather from the later parts diagrams, I'd say the 70 AMP doesn't interchange with the 100AMP alternator without a lot of extra work & parts swaps. it also appears that the 100 amp unit is from Balmer and has an internal regulator. I'd think that getting your existing unit overhauled would be the best course.....

    overall, Balmer has had a good reputation.....some of their newer products have left some people with a non-positive attitude.....

  10. #10
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by makomark View Post
    slow cruiser:

    From what I gather from the later parts diagrams, I'd say the 70 AMP doesn't interchange with the 100AMP alternator without a lot of extra work & parts swaps. it also appears that the 100 amp unit is from Balmer and has an internal regulator. I'd think that getting your existing unit overhauled would be the best course.....

    overall, Balmer has had a good reputation.....some of their newer products have left some people with a non-positive attitude.....
    That's what I thought, not a simple replacement. There must be a reason for the 'substantial' price difference.
    I'm going to check it again this weekend and look into having a local shop rebuilt it.

  11. #11
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    Default Re: Starboard alternator over charged

    there is - its called Balmar.....

  12. #12
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    Western NY
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by RicardoMarine View Post
    Most all marine alternators cut back on the charge rate rather quickly.
    I agree....... 100 amp is over-kill.

    I'd also be willing to bet that the OEM harness is just barely heavy enough to effectively handle a continuous 100 amp charge rate.
    The cables are 4/0, no problem.

  13. #13
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    Default Re: Starboard alternator over charged

    Quote Originally Posted by slow cruiser View Post
    That's what I thought, not a simple replacement. There must be a reason for the 'substantial' price difference.
    I'm going to check it again this weekend and look into having a local shop rebuilt it.
    I found the wiring/installation diagram from Balmar, it was a loose wire. Check the simple things first, I had over looked this the first time.

  14. #14
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    Default Re: Starboard alternator over charged

    That doesn't happen too often....glad that's resolved...

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