Need Alternator Expertise Please!
Thread Starter
Pro
Joined: Apr 2005
Posts: 666
Likes: 5
From: Mt. Pleasant SC
Need Alternator Expertise Please!
I installed a new (reman) 85 amp alt in my 73 two mos ago. All was well until this weekend when I noticed the guage on startup pegging out at +40. After running for a few minutes it settled down to normal reading, but when I put a load on it (A/C, heater, etc) the guage jumped back up again to nealy +35 and held there. Had the unit bench tested today and it read steady at 14 volts...appearing to be operating normal. Could the regulator be faulty even though the bench tester indicated normal volts? Any ideas or recommendations would be appreciated.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 439
From: Wellington, FL
St. Jude Donor '11 thru '25
I think it's operating normally. After start up, the charging system will pull more amps to recharge the battery. Also, when you turn on your asccessories, the same thing is happening. Your amp gauge should be slightly to the plus side under normal opearation.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Before you condemn the Alt., I'd take a hard look at the battery, especially if it started right when it got cold. Doesn't mean it's bad, it just not as good as it was... Check standing voltage right before you fire it up, then run it 'till it settles down and check it again after it stabilizes (5-10 minutes after shut-down). After that, check the voltage with all the accessories off, then on. Between that and the amp gauge (which are fairly accurate in vettes), you'll have a better idea.
Hans
Hans
Thread Starter
Pro
Joined: Apr 2005
Posts: 666
Likes: 5
From: Mt. Pleasant SC
Before you condemn the Alt., I'd take a hard look at the battery, especially if it started right when it got cold. Doesn't mean it's bad, it just not as good as it was... Check standing voltage right before you fire it up, then run it 'till it settles down and check it again after it stabilizes (5-10 minutes after shut-down). After that, check the voltage with all the accessories off, then on. Between that and the amp gauge (which are fairly accurate in vettes), you'll have a better idea.
Hans
Hans
Thanks,
Chris
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Thats right, starting the car is useing a lot of the battery charge and the alternator is recharging the battery and as stated above accessories add to the load the alternator is supporting and it shows up on the gauge as it should. You battery may not be bad, just not as good as new like Wrencher says
