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Charging question

Old Oct 9, 2009 | 07:01 PM
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I have an 81. It has been running fine , but today the charging light started coming on, as well as the choke light. When I rev it up the light gets brighter... real bright, at idle the choke light is off but lights up along with the voltage/charge light. The nominal voltage of the battery seemed fine 12.1 and the voltage went to 13.9 -14.1 with the engine running. I have not had the battery load tested, but it could have a low cell pulling too much load and causing the condition. Does anyone know if the voltage monitoring circuit will do that if it sees a heavy draw on the syatem? Or any other ideas?? Thanks!! Jeff
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Old Oct 10, 2009 | 03:15 PM
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bad alt
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Old Oct 10, 2009 | 05:19 PM
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Thanx S. I did some archives searches and I think I will start there, Thanks Again!
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Old Oct 10, 2009 | 05:25 PM
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throw a voltmeter on the output of the alternator. see what it's putting out..
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Old Oct 10, 2009 | 07:49 PM
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Whats the threshold? 14.1 or 2 anymore the diode is bad?
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Old Oct 10, 2009 | 08:18 PM
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Yea thats about right without looking it up. The main thing is the cgarge light, if it is on it means you probably have a bad diode in the alt. Annother indication is voltage output, anything in the 12z range and it will not charge the battery
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Old Oct 10, 2009 | 08:48 PM
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81pilot

At an idle, 1 volt above battery voltage is ok. The reason for the charge light coming on may be the lack of amperage output. It is possible to have enough volts or pressure but not enough amperage or electron flow. The rectification circuit may have one or more bad diodes. Can you pull the alternator and bring it to a parts store for testing?
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Old Oct 11, 2009 | 03:02 PM
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I agree. It is showing 14.8 volts or better and the charge light is real bright, I think an internal diaode went Kaputt in the regulation circuit inside the alternator.. I will run it down and get it checked tomorrow. Alternators are cheap all things considered and a snap to change....Thanks guys!!
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