Brain buster for the geniouses
09-30-2009, 07:29 AM
#1
Thread Starter
Join Date: Sep 2009
Location: NC
Posts: 1
Brain buster for the geniouses
Hi all,
I had a problem develop in my 07 GT yesterday that has me stumped, and I wanted to see if any of you could offer some insight.
The car would not start when I was leaving work around midday yesterday. I had a co-worker jump the car, and it started perfectly. After driving home, the car started up again (but struggled just a bit).
Leaving work in the afternoon, same problem. Would not start.
After another jump, I drove the car to an auto parts store and had the battery tested. They said that the battery was good. I was asked "what is the car doing" so I got in, and sure enough the car started. Strongly. This was after about a 20 minute drive, and the car being off for about 3 minutes.
I couldn't waste any more of the technician's time so I left. After driving across the street and leaving my car off for less than 10 minutes, same problem as the first time.
As of now the car sits in my driveway and will not start. I have ruled out the starter, since the car has no problems when it is jumped. The only two things I believe could be the problem are the battery or the alternator. The battery gauge shows about 60% when the car is on and driving.
My "theory" is that the alternator is providing sufficient charge for the gauge to show a good battery, but the battery is actually the problem.
Can anyone offer any input?
Thank you very much!
I had a problem develop in my 07 GT yesterday that has me stumped, and I wanted to see if any of you could offer some insight.
The car would not start when I was leaving work around midday yesterday. I had a co-worker jump the car, and it started perfectly. After driving home, the car started up again (but struggled just a bit).
Leaving work in the afternoon, same problem. Would not start.
After another jump, I drove the car to an auto parts store and had the battery tested. They said that the battery was good. I was asked "what is the car doing" so I got in, and sure enough the car started. Strongly. This was after about a 20 minute drive, and the car being off for about 3 minutes.
I couldn't waste any more of the technician's time so I left. After driving across the street and leaving my car off for less than 10 minutes, same problem as the first time.
As of now the car sits in my driveway and will not start. I have ruled out the starter, since the car has no problems when it is jumped. The only two things I believe could be the problem are the battery or the alternator. The battery gauge shows about 60% when the car is on and driving.
My "theory" is that the alternator is providing sufficient charge for the gauge to show a good battery, but the battery is actually the problem.
Can anyone offer any input?
Thank you very much!
09-30-2009, 10:04 AM
#3
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
You mean the battery gauge or an ammeter? If you have a volt meter go stick it on the battery terminals on the voltage reading setting and see what you get. It should be around 12.5v with the car off. When it's running you should have 13.5-14.5 or around there somewhere. Do you have a CEL on?
09-30-2009, 12:39 PM
#4
2nd Gear Member
Join Date: Sep 2009
Location: Jax FL
Posts: 442
Somebody else had a similar problem recently and it turned out to be the ground cable on the starter had a bad connection.
But yes, check the voltage across the battery terminals. With the car off should be about 12.5V and with the car running should be about 14.5V. If it isn't 14.5, check the voltages from the battery + to a good ground near the alternator, and then from the alternator + to the battery - and note those voltages.
With the car only being about 3 yrs old, you shouldn't be having problems with either the battery or the alternator. Not saying they won't be at fault, but I wouldn't go replacing them without checking other things first.
But yes, check the voltage across the battery terminals. With the car off should be about 12.5V and with the car running should be about 14.5V. If it isn't 14.5, check the voltages from the battery + to a good ground near the alternator, and then from the alternator + to the battery - and note those voltages.
With the car only being about 3 yrs old, you shouldn't be having problems with either the battery or the alternator. Not saying they won't be at fault, but I wouldn't go replacing them without checking other things first.
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