89 TR two batteries melted in 4 days | FerrariChat

89 TR two batteries melted in 4 days

Discussion in 'Boxers/TR/M' started by the head, Apr 29, 2015.

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  1. the head

    the head Karting

    Mar 6, 2008
    103
    Des Moines IA
    Full Name:
    J. Hedden
    #1 the head, Apr 29, 2015
    My TR has bulged the case on two AGM batteries since the weekend. The initial one was older so I put in a new replacement and it has now done the same thing.

    This is clearly an overvoltage or overcurrent situation coming from the alternator what are the initial electrical tests I can perform before I need to pull the alternator out to be fixed?

    I assume there is a voltage sense wire to regulate power to the alt, I am also told if the bellhousing ground strap does not have good contact that can also be an issue. Any fuses/relays that can cause this on an 89?
     
  2. Turbopanzer

    Turbopanzer F1 World Champ

    Oct 2, 2011
    11,120
    Under a bonnet
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    Panzer
    #2 Turbopanzer, Apr 29, 2015
    It is a GM alternator. The regulator is within the unit itself. You might wish to consider if all grounds are correctly fastened, replacing the entire unit. They have a habit of doing what you have presently.
     
  3. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    romano schwabel
    #3 turbo-joe, Apr 29, 2015
    even if you overcharge a battery - a new one will not quit the job
    let the engine run and check the voltage. you may not have more than 14,4 V at 2500 rpm and up. up to 15 you also have no problem. so please check the voltage form the generator and let us know
     
  4. cheesey

    cheesey Formula 3

    Jun 23, 2011
    1,921
    #4 cheesey, Apr 29, 2015
    there is more to a regulator than the marked voltage... a standard wet cell regulator can fail an AGM Battery, not charge to 100%, etc etc wet cell charging systems are not compatible with AGM batteries
     
  5. the head

    the head Karting

    Mar 6, 2008
    103
    Des Moines IA
    Full Name:
    J. Hedden
    #5 the head, Apr 30, 2015
    Given the first AGM has been in there for 5 years I find that more than a little hard to believe. Additionally I run AGMs in 10 other cars that were built before AGMs were available so that is probably not the issue.
     
  6. the head

    the head Karting

    Mar 6, 2008
    103
    Des Moines IA
    Full Name:
    J. Hedden
    #6 the head, May 20, 2015
    Ok finally was home long enough to test all the wires.

    hooked up (field and ground connector plugged in) the alternator is outputting 18.3v at idle
    next I disconnected the side connector Ground tones out to chassis and engine off the field wire is reading 11.6 which seems about right given the car is discharged slightly.
    Running with the field ground connector unhooked the alternator is outputting 11.8v, field wire is showing the same voltage as the output.

    When I plug the connector back in the alternator goes right back to 18v at idle to me this is sounds like a nuked regulator, is there anything else I should check before changing it out?
     
  7. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    #7 turbo-joe, May 21, 2015
    18,3 V are too high, how much V you have when you have 3000 rpm?
    normal you have max. 14,4 V
    so replace the regulator bu tthen just have a look at the copper rings where the regulator brushes are on.
     
  8. the head

    the head Karting

    Mar 6, 2008
    103
    Des Moines IA
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    J. Hedden
    #8 the head, May 21, 2015
    I have a new alternator for it I am going to put in then have this one rebuilt as a backup.
     
  9. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    southwest germany and thailand
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    romano schwabel
    #9 turbo-joe, May 21, 2015
    the alternator seems to be ok. only the regulator may be wrong
    but good to rebuilt the complete so you may use it at spare part some day
     

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