Fluctuating Voltage
Thread Starter
Burning Brakes
Joined: Jun 2000
Posts: 961
Likes: 0
From: Layton UT
Fluctuating Voltage
Lately my car voltage has been fluctuating a lot. It used to say pretty steady from 13.9 to 14.1. Now it will chage two tenths about every 5 seconds or less. It can go as high as 14.9. Is this a sign of my alternator going bad..or something worse? Thanks.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Fluctuating Voltage (GlobalGreg)
Remove your battery cables, clean them and the battery posts and replace. 14.9 volts is out of range because the alternator voltage regulator is designed to maintain 14.3 to 14.7 volts and this will drop when the alternator warms up to about 13.5 or so. Fluctuations are normal and nothing to worry about.
Thread Starter
Burning Brakes
Joined: Jun 2000
Posts: 961
Likes: 0
From: Layton UT
Re: Fluctuating Voltage (jfb)
Fluctuations are normal and nothing to worry about.
Sergeant
Joined: Jul 2001
Posts: 443
Likes: 1
From: Clarksville FL
Re: Fluctuating Voltage (GlobalGreg)
I can also see the lights dimming on the dash and sometimes I can see the headlights dim...and all you think it is is the battery cables? I hope so, a lot cheaper than a alternator!
Pro
Joined: Oct 2001
Posts: 525
Likes: 0
From: Newport MI
Re: Fluctuating Voltage (GlobalGreg)
If the battery cables check out... It is likely the brushes in the alternator being worn down (short, such that spring tension isn't enough to keep the brush firmly seated against the slip rings)
(The electronic voltage regulator generally just fails... the old spring type regulator of the early 70's & before would show this symptom @ 1st)
2 options..
replace the brushes (I'm not sure you can do this on a CE style GM alternator)
replace the alternator
[Modified by Shark ssn591, 12:24 PM 11/13/2001]
(The electronic voltage regulator generally just fails... the old spring type regulator of the early 70's & before would show this symptom @ 1st)
2 options..
replace the brushes (I'm not sure you can do this on a CE style GM alternator)
replace the alternator
[Modified by Shark ssn591, 12:24 PM 11/13/2001]
Pro
Joined: Oct 2001
Posts: 525
Likes: 0
From: Newport MI
Re: Fluctuating Voltage (GlobalGreg)
Lately my car voltage has been fluctuating a lot. It used to say pretty steady from 13.9 to 14.1. Now it will chage two tenths about every 5 seconds or less. It can go as high as 14.9. Is this a sign of my alternator going bad..or something worse? Thanks.
[Modified by Shark ssn591, 12:29 PM 11/13/2001]
Intermediate
Joined: Jun 2000
Posts: 28
Likes: 0
From: monaca pa
Re: Fluctuating Voltage (GlobalGreg)
I have a 94 LT1 and my volt gauge fluctuates between 14.3 and 15 volts. If the car has not been driven for more than a week it will read 15 volts on startup. After warmup and driven it usually falls to 14.3 and remains there regardless of the load. Battery is two years old.
According to the 94 service manual if your volt meter reads between 13-16 volts the system is operating normally.You have a CS-144 charging system and the regulator within the alternator is temperature compensated which in turn limits system voltage by controlling rotor field current. In order to do a system checkout you will need to have a digital multimeter, carbon pile between 30-500 ohms and an ammeter.
I believe your charging system is working correctly
According to the 94 service manual if your volt meter reads between 13-16 volts the system is operating normally.You have a CS-144 charging system and the regulator within the alternator is temperature compensated which in turn limits system voltage by controlling rotor field current. In order to do a system checkout you will need to have a digital multimeter, carbon pile between 30-500 ohms and an ammeter.
I believe your charging system is working correctly
Burning Brakes
Joined: Oct 2000
Posts: 1,241
Likes: 0
From: phila. pa .usa
Re: Fluctuating Voltage (steve bavaro)
while drivin yesterday my voltage went from 14.1 to 11.2 , alternator is 2months old(pepboys life. guaran.), double checked it with tester=same , got replacement in ,took batt. out to charge, voltage reg. only lasted 2 months ,hope it doesnt last 2 months again. :smash: :smash:
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Thread Starter
Burning Brakes
Joined: Jun 2000
Posts: 961
Likes: 0
From: Layton UT
Re: Fluctuating Voltage (steve bavaro)
I believe your charging system is working correctly
Burning Brakes
Joined: Dec 2000
Posts: 1,161
Likes: 0
From: Orangeburg, NY
Re: Fluctuating Voltage (GlobalGreg)
I would suggest that before you do anything, check your battery with a hydrometer. You may have a cell that is going bad.
You may also want to check the condition of your fanbelt. It may be slipping. Even though there is an automatic tensioner, the belt may be getting worn out, not turning the alternator enough to produce enough current at low rpm's, thus causing a draw on the battery. If the above check out , then it may be time to replace the alternator.
You may also want to check the condition of your fanbelt. It may be slipping. Even though there is an automatic tensioner, the belt may be getting worn out, not turning the alternator enough to produce enough current at low rpm's, thus causing a draw on the battery. If the above check out , then it may be time to replace the alternator.
