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15.1 volts too much alternator output?

Discussion in 'The Garage' started by Ned Kelly, Mar 9, 2005.

  1. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    My old alternator was putting out less than 11 volts, so I picked up a new one. After I installed the new one I measured the output at 15.1 volts. Is this too much and will it 'cook' my battery? :confused:
     
  2. Fierospeeder

    Fierospeeder Banned

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    should be fine. Just make sure it doesn't start getting any higher
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I'm not sure, but the highest I've ever seen mine at was 14.3 or so.

    Rene
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I'd say that you have to have a short somewhere or something to be putting that kind of load on an alternator, unless the voltage regulator is messed up.
     
  5. Mantruck-k5

    Mantruck-k5 Registered Member

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    Sounds too high

    Mine currently reads 14.9 so I started investigating. I read on a tech sight that below 13.5 at 2000 RPM is too low and above 15 volts at 2000 is too high. Sorry but I can't find the link again.
    Do you have any electrical equipment that pulls a ton of voltage?
    Also, next time you might want to consider rebuliding your alternator instead of buying a new one. It's cheaper and fairly easy but there's no "lifetime" guarantee.
     
  6. Mantruck-k5

    Mantruck-k5 Registered Member

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  7. Fierospeeder

    Fierospeeder Banned

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    Im assuming his battery is close to being completely dead when his old alternator wasn't charging. So the new alternator sees a battery that is very drained.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Even with a heavy draw like a near dead battery, the voltage regulator should prevent the output from getting to far out of the range.

    When my last alternator went I had short periods where the voltage would spike to 18 volt+ (driving at night...very bright headlights :crazy: ) and then it would drop down to normal. Eventually it packed it in.

    When I had a dead short it also did the same but even worse, supplying so much voltage it burned out all 4 headlights in under 15 seconds.

    I'd be a little concerned with 15.1 volts...maybe enough to bring the alt back.

    Rene
     
  9. Ned Kelly

    Ned Kelly 1/2 ton status Premium Member

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    I know 15 v is supposed to be the outer limit for 'ok', so 15.1 crosses it by a hair. The battery is fully charged and at no load it still cranks out 15.1 volts. I'll take the alternator back and get a different one just to be safe. Thanksf for all the info guys.
     

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