Battery will not hold a charge
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Look at the voltage reading after startup; it should jump into the 14+Vdc range and settle back to mid 13+Vdc range after charged.
If this happens then something is likely discharging the battery after the engine is shut off.
If this happens then something is likely discharging the battery after the engine is shut off.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
More likely you have excessive leakage current (battery current with ign off). At night check for underhood lights, vanity mirror lights, door map lights, center console light, Do you have a radar detector, CB, aftermarket alarm, aftermarket radio or audio amplifier, GPS, check em. Remove the negative battery terminal and connect an ammeter from the cable to the neg battery terminal and after the courtesy lights time out, switch your ammeter down to lower scales and measure the current. GM says leakage current should not exceed 50 milliamps, my 87 draws 27 ma. If you do have high leakage, pull the courtesy fuse, then watch the ammeter while you pull fuses one at time to see if you have a sudden drop in leakage. Further investigation of that circuit will then be required. Also, when you ask for help, state what year C4 you have, they are not all alike. Be sure to recharge your battery with a charger overnight or for a full day, batteries left discharged become door stops.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Did you have the battery load tested? Take it to a reputable shop and have the test done, they will charge the battery and test it. It will be easy to tell if the battery is good or not.
What is the battery voltage with the negative cable removed? If voltage is around 12.1 or less, the battery is probably toast.
Even if the voltage display on the dash shows 14v or so with the motor running, the battery could still not be taking a charge. 13.8v to 14.5v or so indicates that the alternator is producing a sufficient amount of power but if the battery is not being charged from alternator output, the alternator can eventually be ruined.
Checking for a current draw will have to be done if the battery checks out as good and the alternator is generating the proper voltage range.
You do need to post the year of the car too.
What is the battery voltage with the negative cable removed? If voltage is around 12.1 or less, the battery is probably toast.
Even if the voltage display on the dash shows 14v or so with the motor running, the battery could still not be taking a charge. 13.8v to 14.5v or so indicates that the alternator is producing a sufficient amount of power but if the battery is not being charged from alternator output, the alternator can eventually be ruined.
Checking for a current draw will have to be done if the battery checks out as good and the alternator is generating the proper voltage range.
You do need to post the year of the car too.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Partial Quote from C4cruiser"
if the battery is not being charged from alternator output, the alternator can eventually be ruined.
++++++++++++++++++++++++++++++++++++++++ ++++++++
That is completely false! If the alternator is not supplying current to the battery, then the only current the alternator is supplying is that to the car which it does normally. Normal alternator current won't ruin an alternator!
if the battery is not being charged from alternator output, the alternator can eventually be ruined.
++++++++++++++++++++++++++++++++++++++++ ++++++++
That is completely false! If the alternator is not supplying current to the battery, then the only current the alternator is supplying is that to the car which it does normally. Normal alternator current won't ruin an alternator!
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
Instructor
Joined: Jul 2007
Posts: 222
Likes: 0
From: Toronto(Don Mills) Ontario
Sounds like what happened to me, last year, when a 2 year old Delco died on me - would not hold enough of a charge to re-start the Vette, even after a boost, then re-charge. Turned out to be a dead/shorted cell! Battery was toast!
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Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
More likely you have excessive leakage current (battery current with ign off). At night check for underhood lights, vanity mirror lights, door map lights, center console light, Do you have a radar detector, CB, aftermarket alarm, aftermarket radio or audio amplifier, GPS, check em. Remove the negative battery terminal and connect an ammeter from the cable to the neg battery terminal and after the courtesy lights time out, switch your ammeter down to lower scales and measure the current. GM says leakage current should not exceed 50 milliamps, my 87 draws 27 ma. If you do have high leakage, pull the courtesy fuse, then watch the ammeter while you pull fuses one at time to see if you have a sudden drop in leakage. Further investigation of that circuit will then be required. Also, when you ask for help, state what year C4 you have, they are not all alike. Be sure to recharge your battery with a charger overnight or for a full day, batteries left discharged become door stops.
Good piece of information along with the others. My 94 draws about 29-30 ma and can sit for weeks with no problem. If you measure about 14 volts when its running its probably charging. If it won’t hold charge for a day, then there’s a current draw or new battery is bad perhaps. 
Team Owner
Joined: Oct 2004
Posts: 35,065
Likes: 0
From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
Get a 12V test light. Take off one of the battery cables. Put the test light in line between the battery and the loose cable.
If the light goes on, you have a draw killing your battery.
If the light goes on, you have a draw killing your battery.
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Unplug both power seats. I fought this problem for about 5 years, and one day while in the car working on it I heard a little sound that turned out to be the power seats trying to move. Even if you just sat there very still, car off, they would try to move a little then stop. I unplugged it and never had a problem since. Car sat all winter and started it this spring with no problem! 
There is a process you can go thru to identify the circuit that is causing the problem. But if you get lucky you can try the seat plugs...I have heard they are prone to this problem...even in newer cars today.
There is a process you can go thru to identify the circuit that is causing the problem. But if you get lucky you can try the seat plugs...I have heard they are prone to this problem...even in newer cars today.
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
The voltage will get weaker as you drive and will eventually shut the car off it were the alternator. On a brand new battery I would suspect a draw. Check your headlights for draw as well. Interior lights are a pretty common draw as is the radio.
Safety Car
Joined: Jan 2006
Posts: 3,566
Likes: 4
From: Mt Laurel NJ
St. Jude Donor '06-'07
If it died like that it is the alternator. When the car is running, what does the gauge say? I'll bet it is only charging at about 6 volts. That happen to me the first day I owned my current vette. A new alternator will fix you right up, don't forget to charge the battery w/ one of the cables disconnected from the battery. The ECM does not like battery chargers.
Randy
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
If your alternator is not charging the battery the red battery symbol light on the dash will be lit. Also, your voltmeter will read below 13 volts. Normal operation is for the voltmeter to read 14.3 volts engine cold and this will drop as the alternator warms up until it reaches 13.3 volts. The dash voltmeter reads in error and low with the engine not running.
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
If it died like that it is the alternator. When the car is running, what does the gauge say? I'll bet it is only charging at about 6 volts. That happen to me the first day I owned my current vette. A new alternator will fix you right up, don't forget to charge the battery w/ one of the cables disconnected from the battery. The ECM does not like battery chargers.
Randy
Randy
It is a simple swap
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Partial Quote from RandyJ75:
don't forget to charge the battery w/ one of the cables disconnected from the battery. The ECM does not like battery chargers.
++++++++++++++++++++++++++++++++++++++++ +++++++++++++
You do not have to remove a battery cable to charge your battery. Your alternator does the exact same thing to your battery that a battery charger does and it doesn't harm your ECM.
don't forget to charge the battery w/ one of the cables disconnected from the battery. The ECM does not like battery chargers.
++++++++++++++++++++++++++++++++++++++++ +++++++++++++
You do not have to remove a battery cable to charge your battery. Your alternator does the exact same thing to your battery that a battery charger does and it doesn't harm your ECM.