What is the correct alternator voltage?

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  #1  
Old 09-15-13, 04:02 PM
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What is the correct alternator voltage?

My wife's 95 Monte Carlo Z34 has been having an intermittent pulsing electrical system for about a year and a half now. Most noticeable when there's a heavy draw on the system. The car sat for 3 weeks while we were out of town. First day back to work a week ago her car died on the way home and would just click the starter relay. Charged the battery after I got it home and it fired right up. Now the volts light starts coming on intermittently. Not running the battery would show 13.8 volts after the car sat for two days. With all accessories on and the car running 13.3 volts. Started the car up today and disconnected the battery and it showed 14-15 volts at the cables. Checked the disconnected battery and it showed 14.5v... reconnected the battery still running and it showed 16-17v. My thought is to pull the alternator and have it rebuilt. Real PIA to do this one as it is down low as in front passenger wheel and axle removal.Thoughts??
 
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Old 09-15-13, 04:11 PM
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Gathering that the alternator was putting out 14-15 volts? That's normal, and shouldn't require a rebuild. I know you had the battery charged, but have you had it load tested. It could have bad cells that could give a superficial 13 volts, then die to 8 when a load such as a starter is introduced. Most auto parts stores will load test the battery for free.
 
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Old 09-15-13, 04:30 PM
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Actually it was showing 16-17 volts at last check. Voltage at start up was 12.4v. It's kinda all over the place which is why I was considering a rebuild.
 
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Old 09-15-13, 05:07 PM
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That's why I suggested a "load" test for the battery. Hooking a meter to the battery only shows the residual voltage available, and not the cranking amps. What type meter are you checking the voltage with?
 
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Old 09-15-13, 05:22 PM
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First do not disconnect batt cables and run the vehicle. This was the shade tree way of checking a generator,and can do serious harm to newer cars. I would check both the batt and alt. 17 volts is too high and could damage elec. components. Do you have another batt you could try?
 
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Old 09-15-13, 05:54 PM
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Digital volt meter. And you say bad for newer cars...Who's got one of those? I may have another battery around here somewhere.
 
  #7  
Old 10-02-13, 07:11 PM
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Started the car up today and disconnected the battery and it showed 14-15 volts at the cables. Checked the disconnected battery and it showed 14.5v... reconnected the battery still running and it showed 16-17v.
If the alternator wasn't cooked before you cooked it when you did that.
 
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