Battery problem 96
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Battery problem 96
I noticed that my passenger side door was open, it's probably been 3 days. I went to start the car and just got a clicking sound. I have a battery charger with a starter on it so I used that to get it started. I checked the gauge and the battery was at 14.2. I shut it off to see if it would start again and it did. It's my DD so I had to get to work. no problems on a 40 minute drive and it went up to14.5. drove it home, still at 14.5. I am charging it overnight. I am just curious why it would not initially start but after a jump start, it would keep starting up again. Just want to be sure that the only problem I have is a weak battery from leaving a door open. is 16 about where the battery should be. another question, when I just turn the key on,the gauge registers at only 13 but when you start the car it jumps up to 14.5, why? Thanks
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
12-13 is normal for a battery. It is also normal for the voltage to go around 14-14.5 when running. The reason it goes that high is because the alternator is running to put a charge on the battery and to operate the car and any accessories (radio, lights, charging phone, etc.)
If the voltage goes to 16 that is bad...that means that the regulator inside the alternator is no longer functioning properly.
If the voltage goes to 16 that is bad...that means that the regulator inside the alternator is no longer functioning properly.
Safety Car
Joined: Aug 2002
Posts: 3,842
Likes: 230
From: SANTA CRUZ CA
1986coupe answered your questions.
Also......
You are confusing battery readings with alternator output readings.
With the car "off", your dash voltage should read 12V+. Some voltage is lost going through the ignition, so if you were to read voltage at the batt posts, the reading would be slightly higher.
With the car "running", your dash voltage is reading alternator voltage output, not battery voltage.
The reason the car kept starting after a jump-start, is the battery received a sufficient charge to perform the 'start' task. It could be assumed the battery was not totally discharged due to the door being ajar, and it needed only a little 'help' to function properly. The vette starter is geared, so high voltage/amps are not required to activate the starter. A door ajar only switches the interior lights on, so the amps lost would be related to the number of bulbs illuminated.
16V is not where your charging voltage should be at any time. At first start-up, your gauge could read 14.5V (+/_), and drop a few tenths to around 14V after a few minutes of driving, assuming a healthy battery and alternator. If the gauge remained at 14.5V during your round trip, the alternator was sensing the need to keep charging. In your case, you were dependent on using the alternator to recharge the battery. It is always preferred to use an external charger to recharge the batt.
I hope your charger is an 'automatic' charger that stops charging when it senses a fully charged battery. If not, do not keep charging the battery.
Also......
You are confusing battery readings with alternator output readings.
With the car "off", your dash voltage should read 12V+. Some voltage is lost going through the ignition, so if you were to read voltage at the batt posts, the reading would be slightly higher.
With the car "running", your dash voltage is reading alternator voltage output, not battery voltage.
The reason the car kept starting after a jump-start, is the battery received a sufficient charge to perform the 'start' task. It could be assumed the battery was not totally discharged due to the door being ajar, and it needed only a little 'help' to function properly. The vette starter is geared, so high voltage/amps are not required to activate the starter. A door ajar only switches the interior lights on, so the amps lost would be related to the number of bulbs illuminated.
16V is not where your charging voltage should be at any time. At first start-up, your gauge could read 14.5V (+/_), and drop a few tenths to around 14V after a few minutes of driving, assuming a healthy battery and alternator. If the gauge remained at 14.5V during your round trip, the alternator was sensing the need to keep charging. In your case, you were dependent on using the alternator to recharge the battery. It is always preferred to use an external charger to recharge the batt.
I hope your charger is an 'automatic' charger that stops charging when it senses a fully charged battery. If not, do not keep charging the battery.
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
okay, so my battery was only slightly discharged as they only lights on were the 2 in the cargo area. since it is at 14.5 I should be okay, I just needed a bit of a boost to initially get it started. My charger does have an auto shut off when the battery is fully charged so I am guessing I should be okay if it takes a full charge and the gauge is reading around 14.5. Thanks guys, as usual this forum keeps me up and going, I would not stand a chance on my own
Drifting
Joined: Aug 2004
Posts: 1,430
Likes: 2
1986coupe answered your questions.
Also......
You are confusing battery readings with alternator output readings.
With the car "off", your dash voltage should read 12V+. Some voltage is lost going through the ignition, so if you were to read voltage at the batt posts, the reading would be slightly higher.
With the car "running", your dash voltage is reading alternator voltage output, not battery voltage.
The reason the car kept starting after a jump-start, is the battery received a sufficient charge to perform the 'start' task. It could be assumed the battery was not totally discharged due to the door being ajar, and it needed only a little 'help' to function properly. The vette starter is geared, so high voltage/amps are not required to activate the starter. A door ajar only switches the interior lights on, so the amps lost would be related to the number of bulbs illuminated.
16V is not where your charging voltage should be at any time. At first start-up, your gauge could read 14.5V (+/_), and drop a few tenths to around 14V after a few minutes of driving, assuming a healthy battery and alternator. If the gauge remained at 14.5V during your round trip, the alternator was sensing the need to keep charging. In your case, you were dependent on using the alternator to recharge the battery. It is always preferred to use an external charger to recharge the batt.
I hope your charger is an 'automatic' charger that stops charging when it senses a fully charged battery. If not, do not keep charging the battery.
Also......
You are confusing battery readings with alternator output readings.
With the car "off", your dash voltage should read 12V+. Some voltage is lost going through the ignition, so if you were to read voltage at the batt posts, the reading would be slightly higher.
With the car "running", your dash voltage is reading alternator voltage output, not battery voltage.
The reason the car kept starting after a jump-start, is the battery received a sufficient charge to perform the 'start' task. It could be assumed the battery was not totally discharged due to the door being ajar, and it needed only a little 'help' to function properly. The vette starter is geared, so high voltage/amps are not required to activate the starter. A door ajar only switches the interior lights on, so the amps lost would be related to the number of bulbs illuminated.
16V is not where your charging voltage should be at any time. At first start-up, your gauge could read 14.5V (+/_), and drop a few tenths to around 14V after a few minutes of driving, assuming a healthy battery and alternator. If the gauge remained at 14.5V during your round trip, the alternator was sensing the need to keep charging. In your case, you were dependent on using the alternator to recharge the battery. It is always preferred to use an external charger to recharge the batt.
I hope your charger is an 'automatic' charger that stops charging when it senses a fully charged battery. If not, do not keep charging the battery.
I am with Sheldon!
Thread Starter
Drifting
Joined: Feb 2009
Posts: 1,302
Likes: 2
From: colchester CT
Thats what I was afraid of. I checked last night and the lights do go out. Don't really know where to start looking but hopefully charging the battery fixes it. I just bought the car a year and a half ago and have know idea how old the battery is so maybe just need a new one. Thanks for the help
