Alternator/charging system question 1972 C3

[george romano]

I just took the Vette out for a short (about 20 miles) drive, and noticed my BATTERY gauge charging at +40 while on the highway. It usually runs just to the right of 0.

At idle it is a little better but not normal.

When I turn on all the electrical devices (high beams, heater fan on high, foot on the brake) it will get closer to normal, but still not where it usually runs.

Is this an indication of a battery or alternator problem? The battery was installed by the previous owner in fall 1998, and the alternator is the original.
The car hasn't been driven much so far this summer, but it does get out every so often. Never do I start it up and shut it right down; if it gets started it will always run for at least a 15 or 20 minute drive.

As a note, the gauge will normally start out charging at +30 or so upon initial start up, but goes back to the normal range soon after. It is now staying at high charge.
What should I check?

Thanks in advance!

George

[Stephen L.]

Re: Alternator/charging system question 1972 C3

Sounds like the charging system is working. You may have a bad cell in the battery. Check the battery voltage with the engine off. Should be about 12.5v Then turn on the lights. If the voltage drops significantly you have a cell going south..... A 1998 battery is stretching its life span, even if its not used much.
If you are unsure about the voltage levels, do the same procedure on your everyday car...(assuming that one is ok) as a comparison.

[Dick W.]

Re: Alternator/charging system question 1972 C3

Pasta, agree with Steve. It most definitely sounds like that you have at least one cell going "South" in your battery

[george romano]

Re: Alternator/charging system question 1972 C3

I just hooked the Tach&Dwell meter up to the battery posts. It reads 12 volts (or maybe just a TIC over 12) with the engine off, and when I turn on the headlights, it drops a LITTLE to about 11.8 volts or so.
Does that tell you anything?
Sounds to me like the battery is still OK.

Thanks for any advice you can give.

George Pasta

[John Walker]

Re: Alternator/charging system question 1972 C3

George; 13.2 is the proper voltage reading for a fully charged 12 volt battery. 11.8 would probably indicate that the battery is going "south". John

[Kurt G.]

Re: Alternator/charging system question 1972 C3

George, someone else said you're living on borrowed time. The borrowed time on any lead acid battery was over about 4 years from the time the battery was assembled. I'd recommend you plunk down $85 bucks on a new Delco battery and move on down the road. What your charging system is trying to tell you is you have one or more cells in the battery that have either failed, or more likely bridged. This is a build-up of lead oxide that developes on the plates over time, and will eventually connect two or more plates together, creating a short. This signals the charging system that these cells are low, and creates an excitement of the alternator field to put more juice into the system. What you will probably find is you will be on your way to a show or breakfast some day, your car will start fine at home, but is dead as a mackerel when you get in to go home, of course on Sunday morning when everything is closed.

[george romano]

Thanks All! Appreciate the help GREATLY. *NM*

[george romano]

Turns out it was the voltage regulator after all.

Thanks again guys.

Pasta