Normal battery voltage?
Thread Starter
Racer
Joined: Oct 2012
Posts: 458
Likes: 22
From: OK
Normal battery voltage?
Been having battery drain issues, but hoping that has been corrected now. This question is to see if it might have been, or still not right.
After the car has been off for awhile, I go out and press the green button, but not the clutch as to start it. All the gauges come on and the typical Corvette start up sequence. When that is done, the battery voltage reads 11.8. When I start the car, after a few seconds it jumps to around 14.2. When driving, that increases to 14.4-14.6. Does all of this sound normal, or is that voltage when the car is not running sound too low?
Thanks!
After the car has been off for awhile, I go out and press the green button, but not the clutch as to start it. All the gauges come on and the typical Corvette start up sequence. When that is done, the battery voltage reads 11.8. When I start the car, after a few seconds it jumps to around 14.2. When driving, that increases to 14.4-14.6. Does all of this sound normal, or is that voltage when the car is not running sound too low?
Thanks!
Thread Starter
Racer
Joined: Oct 2012
Posts: 458
Likes: 22
From: OK
Thanks for the input. This battery has been completely drained and charged back up 3 times in the past month, should I just fire a new battery in there?
Pro
Joined: Nov 2012
Posts: 683
Likes: 140
From: Cookeville TN
The static level of the battery should be 12.2 to 12.8 if off for a short time and closer to 12.0 sitting longer......your running level sounds good also, but 11.? is a problem slowly showing its ugly head.
Team Owner
Joined: Nov 2007
Posts: 45,273
Likes: 8,545
From: Rochester, NY
Racer
Joined: May 2010
Posts: 299
Likes: 1
From: West Milford NJ
As stated by the gentleman from the Cumberland Plateau.... a new battery should register 12.8 volts when not being charged. The older it gets the lower the voltage will be. The chart below shows that your battery is dead It could also be that your volt meter is off....... or your battery still has a parasitic draw. None of this is good news.
State of Charge Specific Gravity Voltage
12V 6V
100% 1.265 12.7 6.3
75% 1.225 12.4 6.2
50% 1.190 12.2 6.1
25% 1.155 12.0 6.0
Discharged 1.120 11.9 6.0
State of Charge Specific Gravity Voltage
12V 6V
100% 1.265 12.7 6.3
75% 1.225 12.4 6.2
50% 1.190 12.2 6.1
25% 1.155 12.0 6.0
Discharged 1.120 11.9 6.0
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Melting Slicks
Joined: Oct 2008
Posts: 2,098
Likes: 8
From: Dayton Ohio
You are correct, even though 11.8 volts doesn't "sound" that bad. If you measured the battery voltage at the battery terminals and it came up at 11.8 volts, your battery should be "dead" at that point. Do you have access to a multimeter? I'd be curious to know what your actual battery voltage is measured at the battery. I'm not sure how accurate the DIC is.
In any case, if you think you have battery issues (and it sounds like you do), don't just throw a battery in it for the sake of replacing it. Charge the battery up and have it LOAD tested. That is the only way to determine its true condition. Any Batteries Plus can do it for free. I'd tell you to go to AutoZone, but I try to stay away from there if I can.
In any case, if you think you have battery issues (and it sounds like you do), don't just throw a battery in it for the sake of replacing it. Charge the battery up and have it LOAD tested. That is the only way to determine its true condition. Any Batteries Plus can do it for free. I'd tell you to go to AutoZone, but I try to stay away from there if I can.
Instructor
Joined: Feb 2011
Posts: 230
Likes: 0
From: Mission Viejo CA
You are correct, even though 11.8 volts doesn't "sound" that bad. If you measured the battery voltage at the battery terminals and it came up at 11.8 volts, your battery should be "dead" at that point. Do you have access to a multimeter? I'd be curious to know what your actual battery voltage is measured at the battery. I'm not sure how accurate the DIC is.
In any case, if you think you have battery issues (and it sounds like you do), don't just throw a battery in it for the sake of replacing it. Charge the battery up and have it LOAD tested. That is the only way to determine its true condition. Any Batteries Plus can do it for free. I'd tell you to go to AutoZone, but I try to stay away from there if I can.
In any case, if you think you have battery issues (and it sounds like you do), don't just throw a battery in it for the sake of replacing it. Charge the battery up and have it LOAD tested. That is the only way to determine its true condition. Any Batteries Plus can do it for free. I'd tell you to go to AutoZone, but I try to stay away from there if I can.
I am not sure how accurate the DIC is, your best bet is to check with a VOM at the battery. Also, a static reading is not the best way to tell the condition of the battery. While 11.8 volts may not sound that bad, how does it do with even a little load on it. Even just turning your lights on. I bought a tester from Griots Garage that has a resistance tester built in and tests the battery voltage with a load on it.If the voltage drops significantly you need a new battery.
Good luck
Melting Slicks
Joined: Oct 2008
Posts: 2,098
Likes: 8
From: Dayton Ohio
No, I don't think a car battery with a static voltage of 11.4 would be strong enough to turn the engine over. By static voltage, I mean the battery isn't hooked up to anything and there is no load on it when the voltage reading is taken.
I know it's hard to get your head around the logic of battery voltage numbers. When you first look at it, the numbers don't seem to make sense: A fully charged car battery will read about 12.6 volts. 11.4 volts is 90% of 12.6...but 11.4 volts means your battery is less than 25% charged.
I know it's hard to get your head around the logic of battery voltage numbers. When you first look at it, the numbers don't seem to make sense: A fully charged car battery will read about 12.6 volts. 11.4 volts is 90% of 12.6...but 11.4 volts means your battery is less than 25% charged.
Instructor
Joined: Feb 2011
Posts: 230
Likes: 0
From: Mission Viejo CA
It still could, but I think there is too much emphasis on static voltage here on this thread. What counts is what does your battery do when it needs to put out the couple hundred amps to start your engine. The voltage on a good battery is going to drop to maybe 6 volts while it is putting out that kind of current.
That is why as several people have already said the best thing to do is load test your battery. Or, fully charge your battery on an equalize charge for 6-12 hours and then float charge for 24 hours. If after all that it is still only putting out 11.4 vots with a good VOM then your battery is not holding a charge and its days are numbered.
That is why as several people have already said the best thing to do is load test your battery. Or, fully charge your battery on an equalize charge for 6-12 hours and then float charge for 24 hours. If after all that it is still only putting out 11.4 vots with a good VOM then your battery is not holding a charge and its days are numbered.
Pro
Joined: Nov 2012
Posts: 683
Likes: 140
From: Cookeville TN
I would say it would be very slugish starting if it did start, you are asking for more problems trying to start a car with low battery power.......starter damage, PCM maybe not trying to scare you but low battery amperage isn't good period. Take it to an auto parts place they should give you the route to go.........get a new battery and be done with this problem.
Race Director
Joined: Apr 2007
Posts: 16,025
Likes: 1,656
From: Toronto, Canada
C7 of the Year - Unmodified Finalist 2021
Been having battery drain issues, but hoping that has been corrected now. This question is to see if it might have been, or still not right.
After the car has been off for awhile, I go out and press the green button, but not the clutch as to start it. All the gauges come on and the typical Corvette start up sequence. When that is done, the battery voltage reads 11.8. When I start the car, after a few seconds it jumps to around 14.2. When driving, that increases to 14.4-14.6. Does all of this sound normal, or is that voltage when the car is not running sound too low?
Thanks!
After the car has been off for awhile, I go out and press the green button, but not the clutch as to start it. All the gauges come on and the typical Corvette start up sequence. When that is done, the battery voltage reads 11.8. When I start the car, after a few seconds it jumps to around 14.2. When driving, that increases to 14.4-14.6. Does all of this sound normal, or is that voltage when the car is not running sound too low?
Thanks!
Team Owner
Joined: Sep 2000
Posts: 25,019
Likes: 2,713
From: Far NW 'burbs of Chicago
St. Jude Donor '13
2009 coupe.
New Delco battery about 4 months/3k miles ago. Temp in my garage is 32', battery had been on a tender for a day and was showing fully charged. Using the "run but don't start" function on the switch, just after removing the tender, the DIC shows 12.0 volts with the headlights off.
EDIT: Two hours after removing the tender in the cold garage, DIC volatage has dropped from 12.0 to 11.9
With the old battery, which was still working just fine but replaced as a precaution, I'd get about 11.8 volts after sitting overnight. Our 2006 was about the same.
I'm not sure if the DIC readouts are a little low, or the various electrical loads on the battery which we can't turn off, drag the voltage down.
Of course, once we start the engine then we are reading alternator voltage instead of battery voltage.
New Delco battery about 4 months/3k miles ago. Temp in my garage is 32', battery had been on a tender for a day and was showing fully charged. Using the "run but don't start" function on the switch, just after removing the tender, the DIC shows 12.0 volts with the headlights off.
EDIT: Two hours after removing the tender in the cold garage, DIC volatage has dropped from 12.0 to 11.9
With the old battery, which was still working just fine but replaced as a precaution, I'd get about 11.8 volts after sitting overnight. Our 2006 was about the same.
I'm not sure if the DIC readouts are a little low, or the various electrical loads on the battery which we can't turn off, drag the voltage down.
Of course, once we start the engine then we are reading alternator voltage instead of battery voltage.
Last edited by Gearhead Jim; Dec 30, 2012 at 08:55 PM.
Melting Slicks
Joined: Oct 2008
Posts: 2,098
Likes: 8
From: Dayton Ohio
I just ran some quick voltage tests on my daily driver (2009 Pontiac) and found the following:
Conclusion: You can't get an accurate static voltage reading using the DIC if you have to power the car up to see it. As soon as you power the car up into "Accessory" mode, it will pull the battery voltage down close to .5 volts. Guess I never noticed this because I don't have my C6 any more.
So a DIC voltage in the high 11 volt range (when the engine isn't running) is normal after all. 
DIY LOAD TEST
Monitor the battery voltage as you start the car. If it remains above 9.6 volts while the engine is cranking, your battery is doing OK. But I'm not sure if you can actually see the voltage reading on the DIC when the engine is cranking?
- Battery voltage measured at the battery terminals with key OFF, no interior lights or any accessories: 12.7 Volts
- Battery voltage measured at the cigarette lighter outlet with key OFF, no interior lights or any accessories: 12.7 Volts
- Battery voltage measured at the cigarette lighter outlet with key ON, no interior lights or any accessories: 12.3 Volts
- Battery voltage measured at the cigarette lighter outlet with key ON, interior dome light on, and daytime running lights on: 11.9 Volts
Conclusion: You can't get an accurate static voltage reading using the DIC if you have to power the car up to see it. As soon as you power the car up into "Accessory" mode, it will pull the battery voltage down close to .5 volts. Guess I never noticed this because I don't have my C6 any more.
So a DIC voltage in the high 11 volt range (when the engine isn't running) is normal after all. DIY LOAD TEST
Monitor the battery voltage as you start the car. If it remains above 9.6 volts while the engine is cranking, your battery is doing OK. But I'm not sure if you can actually see the voltage reading on the DIC when the engine is cranking?
Advanced
Joined: Jun 2012
Posts: 52
Likes: 1
From: Castle Rock Wa
I would say it would be very slugish starting if it did start, you are asking for more problems trying to start a car with low battery power.......starter damage, PCM maybe not trying to scare you but low battery amperage isn't good period. Take it to an auto parts place they should give you the route to go.........get a new battery and be done with this problem.
Bad battery is also hard on the alternator.
11.4 might start the car, but it would be real slugish turning over.
with a Volt meter(VOM) battery should read 12.0 to 12.7 when charged with motor off. 14 to 14.8 when motor running, of course headlights, big stereo, will pull that number down, hopefully no lower than 13.