Battary/Volt Indicator Question
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
Battary/Volt Indicator Question
My first question is about the volt indicator on my 85. I always thought this gage told you the voltage in the battery. However, after a week of sitting, before starting, my meter will show 11 volts. After starting it jumps to 14 volts. What is the principle about this?
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Last edited by J W Drew; May 9, 2015 at 04:17 PM. Reason: Additional wording
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
My first question is about the volt indicator. I always thought this gage told you the voltage in the battery. However, after a week of sitting, before starting, my meter will show 11 volts. After starting it jumps to 14 volts. What is the principle about this?
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
With the ignition ON and the engine not running, it's typical to see something like 11+ volts. The ignition switch powers up a number of systems like the radio, ECM, fuel pump, and other electronic equipment. That puts a drain on the battery.
A fully charged battery with no load on it would show something like 12.6 to 12.8 volts using a voltmeter. Once the engine starts, the alternator is charging the battery and a display of 14.1 to 14.3 volts is fine. As the battery gets back to a full charge, the regulator drops the alternator output so the battery doesn't get overcharged. 13.2 to 13.7 volts is a good range.
It's possible that the battery may have a dead cell or not holding a charge for some reason. You may want to take the car to a reputable shop to have the battery and charging system checked out. They will do a "load test" on the battery to see if it's actually holding a charge.
How do you know that the alarm system draws a lot of amps?? Do you know what that draw is?
A fully charged battery with no load on it would show something like 12.6 to 12.8 volts using a voltmeter. Once the engine starts, the alternator is charging the battery and a display of 14.1 to 14.3 volts is fine. As the battery gets back to a full charge, the regulator drops the alternator output so the battery doesn't get overcharged. 13.2 to 13.7 volts is a good range.
It's possible that the battery may have a dead cell or not holding a charge for some reason. You may want to take the car to a reputable shop to have the battery and charging system checked out. They will do a "load test" on the battery to see if it's actually holding a charge.
How do you know that the alarm system draws a lot of amps?? Do you know what that draw is?
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
Thanks cruiser. You answered all of my questions. As far as the alarm draw, I only say that because of some of the posts I have seen, mentioning that after market alarm systems, draw a lot of amps. Based on your comments of the voltage I am seeing, it appears I am operating within parameters. I did have my mechanic check for a draw without any systems functioning and there was none. However did not check with the alarm activated. Also we have not done a load test. How is a load test done?
JW
JW
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Shops will have a load test device that connects to the battery and places a fairly heavy amperage load on the battery. The tester will check the volts before and after to determine how fast the battery recovers.
There are new electronic testers that functionally do the same thing but without a heavy load placed on the battery. Some will even provide a printed report or have a digital display that shows the condition of the battery.
Most of the chain parts stores (AutoZone, O' Reilley's, Pep Boys, NAPA, etc.) have the ability to load test a battery and usually at no charge.
There are new electronic testers that functionally do the same thing but without a heavy load placed on the battery. Some will even provide a printed report or have a digital display that shows the condition of the battery.
Most of the chain parts stores (AutoZone, O' Reilley's, Pep Boys, NAPA, etc.) have the ability to load test a battery and usually at no charge.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
The symptoms provided don't indicate a healthy electrical system.
When using a charger, the voltage should never read
11V...... it should read 13.8V+. It is recommended that the charger is 'automatic' vs. 'manual' to prevent overcharging.
At start-up, the voltage can read 14.5V for at least 10 minutes+, then gradually drop to 13.9V+. 13.2V is too low as this may indicate a failing alternator. In theory, a fully charged battery will read 13.2V (2.2V per cell) so 13.2V indicates little, or no charge from the alternator. Most parts houses will load test the alternator for free.
Because the battery is only 3 years old, doesn't mean the battery is working properly. Have the battery load tested, also.
When using a charger, the voltage should never read
11V...... it should read 13.8V+. It is recommended that the charger is 'automatic' vs. 'manual' to prevent overcharging.
At start-up, the voltage can read 14.5V for at least 10 minutes+, then gradually drop to 13.9V+. 13.2V is too low as this may indicate a failing alternator. In theory, a fully charged battery will read 13.2V (2.2V per cell) so 13.2V indicates little, or no charge from the alternator. Most parts houses will load test the alternator for free.
Because the battery is only 3 years old, doesn't mean the battery is working properly. Have the battery load tested, also.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
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
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
If you plan on taking the batt and alt to a parts house, yes, you usually will need to remove them from the vette,
but check with the parts house to confirm that the units need to be removed.
If you take your vette to an auto-electric shop, the test can be done without removing the units, but there may be a charge for the tests. Call ahead to see if there will be a charge for testing.
but check with the parts house to confirm that the units need to be removed.
If you take your vette to an auto-electric shop, the test can be done without removing the units, but there may be a charge for the tests. Call ahead to see if there will be a charge for testing.
Last edited by don hall; May 10, 2015 at 01:58 AM.
Burning Brakes
Joined: Nov 2013
Posts: 914
Likes: 277
From: St. Petersburg FL
My first question is about the volt indicator on my 85. I always thought this gage told you the voltage in the battery. However, after a week of sitting, before starting, my meter will show 11 volts. After starting it jumps to 14 volts. What is the principle about this?
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
If it was sitting with the Battery Tender connected, you're original voltage before start up should be at least 12 volts. If it was sitting without the Battery Tender connected, your gauge is showing numbers consistent with a healthy electrical system and a 3-year old battery.
A suggestion to extend the life of your current battery (and any future batteries) would be to use your Battery Tender on a regular basis.
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 23
From: Seattle Washington
DrDyno, to answer your question "after sitting a week" refers to without the tender. However, even using the tender I only have about 11.5 volts. before start up. I use the tender plugged into my cig lighter. I believe the battery is sealed so no way the check the acid level.
Thanks,
JW
Thanks,
JW
Pro
Joined: Oct 2010
Posts: 603
Likes: 45
From: Baltimore County MD
Battery
My first question is about the volt indicator on my 85. I always thought this gage told you the voltage in the battery. However, after a week of sitting, before starting, my meter will show 11 volts. After starting it jumps to 14 volts. What is the principle about this?
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Second question: after driving the car for, say about, 10 miles the volt gage is still showing about 13.2 volts. Why is this. The battery is an AC Delco and about 3 years old and this condition has remained the same since new. I use a battery tender if I know I'm not going to drive the car for a week as the after market alarm draws a lot of Amps.
Thanks,
JW
Drifting
Joined: Mar 2013
Posts: 1,952
Likes: 239
From: Venice Cali.
If you have 2 caps (3 each side) and you can use a screwdriver and pry it open then it is not sealed. Take it out, remove the caps, clean carefully and look in with a flashlight and make sure the level is at the bottom of the plastic sleeves. It will look like a marble. Use only distilled water. I refilled all 3 of my batteries and they are rejuvenated like new. 85 Corvette(Duralast Gold) , 97 Range Rover(Sears Durasomething) , 97 Celica GT(Bosch).
The AAA guy told me my battery was sealed but it is not. Have to throw this in DO not smoke!!! or anything when you do this.
Good Luck
The AAA guy told me my battery was sealed but it is not. Have to throw this in DO not smoke!!! or anything when you do this.
Good Luck
Last edited by xrav22; May 11, 2015 at 12:51 AM.
Burning Brakes
Joined: Sep 2005
Posts: 993
Likes: 3
From: Iowa
Sounds normal to me; as others have stated once you turn the key on you are putting a load on battery and the voltage will drop. Seeing 14ish while running is nothing to be concerned with either as the alternator is doing it's job. As above, if you really want to be sure put a volt meter on the battery as it sits in the car with no load on it and see what it reads. If you see 12.0 to 12.5 you are good to go. Just my .02