Alternator Overcharging
Thread Starter
Intermediate
Joined: Mar 2007
Posts: 45
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Alternator Overcharging
Need help in figuring this out. My alt. gauge hits the red and dummy light goes on but not all the time. Last year I replace the internal regulator and thougt it was fixed. Last week it happened again. Don't know if I should replace the alternator or if its in the wiring/connection. Has anyone had this problem?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Do you have access to a multi meter? With the engine running, at idle, with no electrical accessories drawing power...what's the voltage reading at the BAT terminal? Use the engine or mounting bracket for the ground on the multi meter.
Thread Starter
Intermediate
Joined: Mar 2007
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Yes, I do. I will try that and see what reading I get. I did forget to mention that I had the alternator checked (out of the car) by NAPA and Auto Zone and both said the alternator was good. Also had it check by a friend who owns a Merlins Muffler (while installed). He also said it was good.?????
Thread Starter
Intermediate
Joined: Mar 2007
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Ok, tonight I first found out that the connections on the plug for term 1& 2 needed to be replaced. I than used my multi meter at the battery when car running and got a reading of 13.8ish. I than pulled the plug at term 1 & 2 with car running and checked reading at term 2. The reading was 73.7ish. Don't understand that reading and if I even did the test correctly. Can anyone tell me if this was correct and what I should do next. Thanks again!
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Melting Slicks
Joined: Aug 2005
Posts: 2,359
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From: Confusion
Replace the voltage regulator, if you have the original alternator, napa sells a kit with the brushes and get the regulator. I had a 69 Nova with external regulator that went bad, it was blowing the caps off the battery from overcharging. GOOD LUCK..............B
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Need help in figuring this out. My alt. gauge hits the red and dummy light goes on but not all the time. Last year I replace the internal regulator and thougt it was fixed. Last week it happened again. Don't know if I should replace the alternator or if its in the wiring/connection. Has anyone had this problem?
Just curious, did you replace the regulator and such with stock replacement parts or upgrade to high amp components?
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Okay. I get the feeling you tested the alt terminals. I need the voltage readings on the PLUG from 1&2, each to ground.Key on, engine off, alt unplugged. You should be reading battery voltages here. The alt condition is irrelevant here.
Thread Starter
Intermediate
Joined: Mar 2007
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I actually did test the plug also with car on but engine off and don't remember what the readings were. I will test again tonight. Also, I replace the internal regulator last year. Was not an upgrade!
Thread Starter
Intermediate
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So thru all of this I find out that my battery was not charging....so I just replaced it with a new one. Now here are my test results. Car on, engine off, pull plug from alternator and the readings on the plug on the red wire (I think term. #2)= 12.13, the white wire (I think term. #1)=11.76. Both with grounding to the alt. bracket. I also tested the battery while grounding to frame...without key on = 12.45, with key on = 12.21 (both tests with engine off). Sorry so lengthy...wanted to give detail. Hope this all helps and you can help me figure this out.
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
I had a similar problem and it turned out to be a very simple solution. It turned out to be a bad connection at the Positive Batt. post. I replaced the battery connector on the positive cable and the problem was solved. Just food for thought and easy enough to check.
Thread Starter
Intermediate
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Never really had a problem with the light. Tested that per the manual and would go on when the key is turned on and goes off when the engine is on. The needle on the gage is still right around 16 or right before the notch/before the red area. sorry to sound stupid, but nowhere have a had a reading of 13.5....are you talking on the dash or my meter? I noted the readings I am now getting with the new battery on the last msg with the new battery. Also, what is the right reading on the gage when things are "normal"?
