Normal battery levels?
Thread Starter
Pro
Joined: Sep 2005
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From: BFE Oklahoma
St. Jude Donor '06
Normal battery levels?
I am pretty sure I need to change out, or at least charge up the battery in the 'Vette. I was curious how bad the battery is though. Is it worth charging or just replacing? I don't know where to look for normal parameters of a function car battery. When the engine is running, it's at 14.4 Amps. When the car is off, and just the key turned to ON it went all the way down to 11.7 Amps. Is this thing toast? Or do I just need to charge it?? Thanks all! You are the best source of info around!!
Drifting
Joined: May 2000
Posts: 1,917
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From: Southern NH
There's a lot of info related to this topic if you search. The simple answer is the DIC does not provide an accurate battery voltage when the car is off - it always reads a bit low. The DIC/Voltmeter is designed to measure the generator output while the engine is running.
To check the battery, use a digital voltmeter across the battery terminals. A fully charged battery will read ~ 12.66 V after it has stabilized (sitting for a few hours). 12.20V is about 50% charged, and 11.8 is 0% charged. If it can't get above 75% charge (12.4V) then you should consider changing it.
Also, the charge of the battery is only one aspect. You should also perform a load test on it to see if it can't maintain the charge. That will signal a problem inside the battery and that it needs to be changed. I read that one way to test this is with the car off turn the high beams on for a few minutes then turn them off and measure the battery - it should not be lower than before the test.
To check the battery, use a digital voltmeter across the battery terminals. A fully charged battery will read ~ 12.66 V after it has stabilized (sitting for a few hours). 12.20V is about 50% charged, and 11.8 is 0% charged. If it can't get above 75% charge (12.4V) then you should consider changing it.
Also, the charge of the battery is only one aspect. You should also perform a load test on it to see if it can't maintain the charge. That will signal a problem inside the battery and that it needs to be changed. I read that one way to test this is with the car off turn the high beams on for a few minutes then turn them off and measure the battery - it should not be lower than before the test.
Race Director
Joined: Nov 2003
Posts: 12,346
Likes: 5
From: Mustang OK
First, the car's voltage meter and DIC are showing voltage not amps. When the engine is running the meter is reading voltage output from the alternator and with the engine off from the battery. Also, there will be a certain amount of voltage loss in the wiring from the battery and you cannot accurately determine your battery's state of charge in going by the car's voltage meter or DIC. In order to get an accurate reading, you will need to take a voltage reading directly at the battery terminals using an accurate Digital Volt-Ohm Meter (DVOM). Also this will only tell you the battery's state of charge. To fully test the battery, you will also need to do a load test. The link below provides some good information on the proper way to test a battery. Before replacing the battery, have it tested at a competent and trusted shop if you do not have the necessary equipment. You may find that it is fine.
CAR BATTERY FREQUENTLY ASKED QUESTIONS
HTH and good luck!
CAR BATTERY FREQUENTLY ASKED QUESTIONS
HTH and good luck!
Last edited by GrayC5; Sep 8, 2006 at 12:32 AM.
Advanced
Joined: Jan 2006
Posts: 89
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From: Winnipeg MB.
I was getting lower readings like that also when I'd turn the key on after the car was sitting and thought I had a draw because I just put a new Delco battery in but when I check it with a meter it's 12.5 volts.
So don't go by the gauge in the car put a meter on it and see where your voltage is at.
So don't go by the gauge in the car put a meter on it and see where your voltage is at.
Melting Slicks
Joined: Jun 2004
Posts: 3,459
Likes: 671
From: panama city beach florida USA
St. Jude Donor '09
put in a new batt. ooops my bad have some one install it that can read and has all their teeth. you bubba should STEP AWAY FROM THE CAR AND NOT OPEN THE HOOD. 11 amps huh
Team Owner
Joined: May 2001
Posts: 36,836
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Originally Posted by patton
put in a new batt. ooops my bad have some one install it that can read and has all their teeth. you bubba should STEP AWAY FROM THE CAR AND NOT OPEN THE HOOD. 11 amps huh
Cold! Cold blooded I tell'ya! Hey, I once had a phone company guy tell me he wanted to buy a switch "to break one wire", when I asked him how much current he was dealing with, he said "12 volts of current and no amps". 
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Instructor
Joined: Jun 2006
Posts: 222
Likes: 1
From: Rapid City SD
To be on the safe side, you should probably just have a shop test the battery. If you feel confident you can remove it yourself, take it to your local parts store. Most can load test the battery to determine the condition. You also left out a lot of info like: has the car been sitting for a long period of time? How old is the battery? Condition of the cables...etc.
Also, I don't know where you've been looking for info on the charging system, but most service manuals I've read cover this topic thoroughly.
Also, I don't know where you've been looking for info on the charging system, but most service manuals I've read cover this topic thoroughly.
Last edited by mfrejek; Sep 10, 2006 at 11:18 PM.
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Pro
Joined: Sep 2005
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From: BFE Oklahoma
St. Jude Donor '06
Car basically sat a little over a week. I drove it one day, but the rest of the week it sat. And everything looks clean on the battery, cables, etc.....not sure how old the battery is....only had the car a year...wouldn't shock me if it was the original....
