What should voltage be?
06-21-2011, 08:25 PM
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What should voltage be? Hi All,
Just put a new dry cell battery in my 1998 LS1 Auto Camaro. Voltage meter showed a little over 13, and after I put the new battery in and it seemed like the car was shifting better.
The other day I left the glove box open for hours by accident but the car still started and it didn't kill the battery.
What I notice now is that the voltage meter stays right at 13 or a little below and now it just doesn't feel like it's shifting good.... Is this normal? I'm not sure why it would change. BTW when I put the car in reverse or drive the voltage usually drops a little then comes back up, same with the A/C ... is that normal?
Thanks,
Just put a new dry cell battery in my 1998 LS1 Auto Camaro. Voltage meter showed a little over 13, and after I put the new battery in and it seemed like the car was shifting better.
The other day I left the glove box open for hours by accident but the car still started and it didn't kill the battery.
What I notice now is that the voltage meter stays right at 13 or a little below and now it just doesn't feel like it's shifting good.... Is this normal? I'm not sure why it would change. BTW when I put the car in reverse or drive the voltage usually drops a little then comes back up, same with the A/C ... is that normal?
Thanks,
06-21-2011, 09:06 PM
#2
what make/model of battery?
a regular wet-cell lead-acid battery (shitty walmart, sears diehard, autozone) will have an open-circuit voltage across both battery posts of 12.65 volts at 80F ambient temp.
Batteries like optima, and sears die hard platinum which are made by Odyssey battery, are AGM (absorbative glass mat) batteries, they still are technically a wet-cell they have acid electrolyte, and will have a slightly higher open circuit voltage- 12.8 volts at 80F. If you got a gell cell, they have the 12.8 volt at 100% state of charge like the AGM batteries, I would be surprised if you got a gell cell they pretty much came and went because they don't last under real world charging conditions.
when you check the battery voltage with a multimeter, 2 things can happen. If you just had the engine running then the battery was being charged by the alternator and will have a surface charge to it that will last at least 4-6 hours, if you put your meter across the battery posts you will measure a false high voltage reading of 13 volts or more. What you need to do is last the battery sit, preferably overnight or at least 8 hrs to guarantee the service charge has dissipated, then you'll measure correct open circuit voltage. The other thing that can cause a misreading is having the positive and negative battery cables connected to the battery, the car (computer and other electronics) constantly draw from the battery and should be minimal and not really affect a voltage reading but if you don't know you have an excessive draw then you'll measure a lower voltage then what there really is, which is why you are measuring "open-circuit" voltage meaning the battery is disconnected and there is an open circuit between the + and - battery posts.
if you are having shifting problems, and it isn't in your head, battery voltage can definitely cause that but you should notice it on the volt gauge on the dash. What can also cause problems is the alternator giving a bad output that is not clean DC current, and will have an AC ripple to it which will affect electronics. Motor Magazine did a good writeup on a case study about alternator and battery problems a few months ago, long story short you need a dealer or a good shop with an engine analyzer to see that ac voltage to diagnose a bad alternator and/or battery: http://www.motor.com/article.asp?article_ID=1766
then again, being the car that it is your tranny may be on it's way out.
and putting into reverse, or in gear, the engine rpm's generally drop, which means the alternator spins slower for a sec and outputs less voltage which you see on the gauge and is normal. But under all conditions you should have over 13.0 volts, if not then it's a problem.
a regular wet-cell lead-acid battery (shitty walmart, sears diehard, autozone) will have an open-circuit voltage across both battery posts of 12.65 volts at 80F ambient temp.
Batteries like optima, and sears die hard platinum which are made by Odyssey battery, are AGM (absorbative glass mat) batteries, they still are technically a wet-cell they have acid electrolyte, and will have a slightly higher open circuit voltage- 12.8 volts at 80F. If you got a gell cell, they have the 12.8 volt at 100% state of charge like the AGM batteries, I would be surprised if you got a gell cell they pretty much came and went because they don't last under real world charging conditions.
when you check the battery voltage with a multimeter, 2 things can happen. If you just had the engine running then the battery was being charged by the alternator and will have a surface charge to it that will last at least 4-6 hours, if you put your meter across the battery posts you will measure a false high voltage reading of 13 volts or more. What you need to do is last the battery sit, preferably overnight or at least 8 hrs to guarantee the service charge has dissipated, then you'll measure correct open circuit voltage. The other thing that can cause a misreading is having the positive and negative battery cables connected to the battery, the car (computer and other electronics) constantly draw from the battery and should be minimal and not really affect a voltage reading but if you don't know you have an excessive draw then you'll measure a lower voltage then what there really is, which is why you are measuring "open-circuit" voltage meaning the battery is disconnected and there is an open circuit between the + and - battery posts.
if you are having shifting problems, and it isn't in your head, battery voltage can definitely cause that but you should notice it on the volt gauge on the dash. What can also cause problems is the alternator giving a bad output that is not clean DC current, and will have an AC ripple to it which will affect electronics. Motor Magazine did a good writeup on a case study about alternator and battery problems a few months ago, long story short you need a dealer or a good shop with an engine analyzer to see that ac voltage to diagnose a bad alternator and/or battery: http://www.motor.com/article.asp?article_ID=1766
then again, being the car that it is your tranny may be on it's way out.
and putting into reverse, or in gear, the engine rpm's generally drop, which means the alternator spins slower for a sec and outputs less voltage which you see on the gauge and is normal. But under all conditions you should have over 13.0 volts, if not then it's a problem.
06-24-2011, 08:19 AM
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As stated above, use a multi-meter to check your voltage.Battery voltage (when sitting, motor off) should be approx. 12.4 to 12.7 volts.When running at idle should be 13.6 max voltage. $.02
