69 small block ammeter reading
Thread Starter
Instructor
Joined: Jun 2010
Posts: 128
Likes: 0
From: Austin TX
69 small block ammeter reading
Hey guys.! New to the c3 and wondering what is a normal reading on the ammeter with the engine running? Mine is flat lined at zero, and I'm thinking my alternator is going out.
Team Owner
Joined: Sep 2006
Posts: 31,303
Likes: 4,391
From: Westminster Maryland
Hi Fiend,
"The ammeter indicates the rate at which the battery is being charged. The Delcotron charging system, (alternator), is equipped with a regulator which controls the charge according to battery requirements. A discharge will be shown if the current demand is more than the Delcotron output. With the battery fully charged the charging rate will be low thus giving an indication of battery condition."
That's from the Owner's Manual.
On my 71 the needle moves just to the right of '0' for a couple of minutes after start up. If I turn the lights, radio, etc. on, without starting the engine, the ammeter needle moves a little bit to the right.
Hope this helps.
Regards,
Alan
"The ammeter indicates the rate at which the battery is being charged. The Delcotron charging system, (alternator), is equipped with a regulator which controls the charge according to battery requirements. A discharge will be shown if the current demand is more than the Delcotron output. With the battery fully charged the charging rate will be low thus giving an indication of battery condition."
That's from the Owner's Manual.
On my 71 the needle moves just to the right of '0' for a couple of minutes after start up. If I turn the lights, radio, etc. on, without starting the engine, the ammeter needle moves a little bit to the right.
Hope this helps.
Regards,
Alan
Thread Starter
Instructor
Joined: Jun 2010
Posts: 128
Likes: 0
From: Austin TX
Thanks for the quick replies guys! 
The ammeter normally stays straight up at 0. If I turn the lights on then it moves a bit to the left, into the negative range.
I ask because I've been having some starting issues lately, but not consistently. Sometimes it will start right up, other times it will not do a thing when I turn the key. Sounds like I may have more digging to do.
The ammeter normally stays straight up at 0. If I turn the lights on then it moves a bit to the left, into the negative range.I ask because I've been having some starting issues lately, but not consistently. Sometimes it will start right up, other times it will not do a thing when I turn the key. Sounds like I may have more digging to do.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
It should really never be in the negative range while running.
If you are using your lights etc or if your battery is discharged or both, it should always read on the positive side.
If negative, check the output of the alternator.
If you are using your lights etc or if your battery is discharged or both, it should always read on the positive side.
If negative, check the output of the alternator.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Three things to check:
Failing starter solenoid; bad connections on main battery wires or engine ground wire (near right side motor mount); weak battery.
You can test a weak battery by watching what the ammeter does immediately after startup. If the ammeter swings up to 20 amps (or so) after starting the engine and quickly returns to '0', your battery is likely very weak and has little starting capacity. With a fully charged battery, the ammeter needle will only read about 10 amps (or lower) and will slowly decrease to '0'.
Failing starter solenoid; bad connections on main battery wires or engine ground wire (near right side motor mount); weak battery.
You can test a weak battery by watching what the ammeter does immediately after startup. If the ammeter swings up to 20 amps (or so) after starting the engine and quickly returns to '0', your battery is likely very weak and has little starting capacity. With a fully charged battery, the ammeter needle will only read about 10 amps (or lower) and will slowly decrease to '0'.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I'm busy today trying to put back together my Saturn I totaled last year.
Thread Starter
Instructor
Joined: Jun 2010
Posts: 128
Likes: 0
From: Austin TX
Thanks again guys. The battery is only two months old and the starter kicks the engine over just fine when the battery is charged. I'm going to have the alternator checked out and go from there.
