1972 Chevy Chevelle Checking alternator output

Tiny
SAMMCC
  • MEMBER
  • 1972 CHEVROLET CHEVELLE
  • V8
  • 2WD
  • AUTOMATIC
  • 66,000 MILES
I have replaced the alternator on my Chevelle 2 times already and am still having issues with the battery going dead if I don't keep it charged. The new alternator has been bench tested at the place of purchase and I am told it is OK. I am trying to determine if it is actually putting out more than battery voltage. If I check the battery with a voltmeter it reads 12.6 volts. With the vehicle running I then check from the larger red wire on the back of the alternator to ground and it also reads the same 12.6 volts. Should this read the same or should I be expecting a 14+ voltage reading?
Sunday, November 9th, 2008 AT 2:28 PM

2 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Full fielding the alternator

Behind the alternator there's a D-hole -stick a screwdriver in the hole and ground the tab-Now read the meter while engine is running should increase above 12.6 volts if so the regulator is defective-No increase points to the alternator again
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Sunday, November 9th, 2008 AT 2:44 PM
Tiny
LOUT5369
  • MECHANIC
  • 217 POSTS
Do you have the stock 37amp alt on this car? Or an upgraded unit, if its stock replace voltage regulator on raditator support, Does your gen lite come on? If the light doesn't work alternator won't charge. Hope this helps. Lou
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Wednesday, July 22nd, 2009 AT 9:56 AM

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