Home | Contact Us | FAQ | Search & Site Map | Link to Us
Sign In | Join | Other 45 Sites in Network
HomeAnnouncements
Discussion Groups
By Brand
BMWChevroletDodgeFordGMHondaLexusMercedes-BenzNissanPeugeotToyotaVolkswagenOther Brands
By Topic
4x4 CarsRVsDrivingMaintenance & RepairCar AudioCollectible Cars
Country Specific
Australian ForumsUK Forums
ArticlesAuto InsuranceBuyingCars & TechnologyMaintenanceMiscellaneousSafety
DMV Resources
Related Topics
MotorcyclesBoatsMore Topics ...

Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / March 2007

Tip: Looking for answers? Try searching our database.

16 volts instead of 12 a problem?

Thread view: 
Enable EMail Alerts  Start New Thread
Thread rating: 
j - 21 Mar 2007 19:37 GMT
I have a 1994 Chevy Corsica with a 6 cylinder engine. In recent days a red
light that is shaped like a battery on the instrument panel has began coming
off and on intermittently. It comes on for a few seconds to a couple
minutes, then stays off for a while. When it comes on, my headlights get
very bright and my heater blower goes very fast. The battery is good. I took
a voltmeter and measured the voltage at the cigarette lighter socket. When
the battery-shaped indicator light is off and everything's normal it reads
14 volts. When the red battery-shaped light is on it reads 16 volts. The car
runs fine either way. This happens during both hot and cold operating
temperatures, light and full electrical load, and there doesn't seem to be a
pattern. I also hear a faint whining noise coming from somewhere when the
light is on.  I thought the alternator was dirty so I sprayed it with a
garden hose and Joy dish soap, but that didn't change anything. I thought
about the voltage regulator, but can't find it. Does anyone know what is
going on here and if it's okay to continue driving the car? Thank you.
HLS@nospam.nix - 21 Mar 2007 19:59 GMT
> I have a 1994 Chevy Corsica with a 6 cylinder engine. In recent days a red
> light that is shaped like a battery on the instrument panel has began coming
[quoted text clipped - 11 lines]
> about the voltage regulator, but can't find it. Does anyone know what is
> going on here and if it's okay to continue driving the car? Thank you.

I wouldn't drive it far that way.   Overvoltage can damage various parts
of the system.

Something is definitely wrong.  It could be the voltage regulator, which is
internal to GM alternators I am familiar with. I would check visually  for
any
obvious wiring problems, then take the alternator in for testing...or, just
take the car to a competent mechanic and let him fix it for you.
AZ Nomad - 21 Mar 2007 20:12 GMT
>Something is definitely wrong.  It could be the voltage regulator, which is
>internal to GM alternators I am familiar with. I would check visually  for
>any
>obvious wiring problems, then take the alternator in for testing...or, just
>take the car to a competent mechanic and let him fix it for you.

It *is* the voltage regulator.  No other component is responsible for voltage
regulation.
Steve - 21 Mar 2007 20:56 GMT
>>Something is definitely wrong.  It could be the voltage regulator, which is
>>internal to GM alternators I am familiar with. I would check visually  for
[quoted text clipped - 4 lines]
> It *is* the voltage regulator.  No other component is responsible for voltage
> regulation.  

Well....... Not entirely true. It can also be something like an
alternator rotor with an internal short to ground. On many alternators,
the regulator works by varying the effective resistance that is in
series with the ground return from the rotor, with battery voltage
always being available to the other terminal of the rotor. If a short to
ground develops in the rotor, the alternator will charge without regulation.
HLS@nospam.nix - 21 Mar 2007 21:33 GMT
> >>Something is definitely wrong.  It could be the voltage regulator, which is
> >>internal to GM alternators I am familiar with. I would check visually  for
[quoted text clipped - 11 lines]
> always being available to the other terminal of the rotor. If a short to
> ground develops in the rotor, the alternator will charge without regulation.

I know that on many alternators you can intentionally bypass the voltage
regulator in order to get DC voltages and currents high enough to power
AC/DC tools.   In case such an connection were made accidentally, then
the result would be higher voltage, regardless of the regulator.  If it can
be done intentionally, then it can happen incidentally.

But I agree with AZ, it is most likely the regulator.
Steve Austin - 22 Mar 2007 00:36 GMT
> I have a 1994 Chevy Corsica with a 6 cylinder engine. In recent days a red
> light that is shaped like a battery on the instrument panel has began coming
[quoted text clipped - 11 lines]
> about the voltage regulator, but can't find it. Does anyone know what is
> going on here and if it's okay to continue driving the car? Thank you.

Alternators hate joy dish soap.  Try dove.
Scott Dorsey - 22 Mar 2007 15:47 GMT
>I have a 1994 Chevy Corsica with a 6 cylinder engine. In recent days a red
>light that is shaped like a battery on the instrument panel has began coming
[quoted text clipped - 11 lines]
>about the voltage regulator, but can't find it. Does anyone know what is
>going on here and if it's okay to continue driving the car? Thank you.

The voltage regulator on this car is built into the alternator.  It has
failed.  It will very soon destroy the battery and may well destroy
thousands of dollars worth of various electronics as well.  Get it
fixed immediately before it destroys the car.
--scott
Signature

"C'est un Nagra.  C'est suisse, et tres, tres precis."

Don Stauffer in Minnesota - 23 Mar 2007 14:40 GMT
> I have a 1994 Chevy Corsica with a 6 cylinder engine. In recent days a red
> light that is shaped like a battery on the instrument panel has began coming
[quoted text clipped - 11 lines]
> about the voltage regulator, but can't find it. Does anyone know what is
> going on here and if it's okay to continue driving the car? Thank you.

Fix it right away.  I used to have a car with a voltmeter display.
One Wednesday I saw an overvoltage condition (usually failure of the
voltage regulator).  I figured to wait till the weekend, when I would
have time to replace the regulator.  Friday evening the battery was
fried.  Had to replace BOTH regulator and battery.

The overcharging heats the battery and drives off electrolyte.  As the
electrolyte gets lower, the internal impedence of the battery goes up,
generating more heat, with boils it off even faster.  This is a
positive feedback runaway condition. It can happen fast, especially in
warm weather.
 
Sign In
Join
My Latest Posts
My Monitored Threads
My Blog
My Photo Gallery
My Profile
My Homepage

Start New Thread
Enable EMail Alerts
Rate this Thread



©2008 Advenet LLC   Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.