battery or alt?
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Teching In
Joined: Sep 2011
Posts: 29
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From: ct
battery or alt? i can get the car to start with cables. once started it idles very low and wants to die. if i give it some gas i can level out the rpms so it will stay running. once i shut it off, it will not restart. and it cut out on me the first time it started. i backed up 20 ft and it died when i let off the gas. could a shot battery cause this or is my alt on its way out. thanks for all your help.
please be the battery, please be the battery, please be the battery, please be the battery, please be the battery,
please be the battery, please be the battery, please be the battery, please be the battery, please be the battery,
It's more than likely a combination of the two. If you're able to jump the car off the alternator should be able to supply enough of a charging voltage to keep it running. Take a multimeter and read battery voltage. A fully charged battery should read about 12.8v. The voltage however, does not always indicate the condition the battery is in. To truly test a battery you'll need to put a load on it. Any parts store has a battery load tester they'll probably let you use in the parking lot.
Jump the car off and test voltage at the battery again. If the alternator is charging properly it should read between 13.8 and 14.4 depending on the RPM. Let me know what you find.
Jump the car off and test voltage at the battery again. If the alternator is charging properly it should read between 13.8 and 14.4 depending on the RPM. Let me know what you find.
Just going to share my experience here, A few weeks ago I put some different tunes on the car and I guess the Optima battery from 2005 had finally gone. It would start up after a few slow turns of the starter but then this week I went to leave town for the day and as I stopped to get gas, I left the radio on for a minute or two and there was no charge left, I got jumped (by a nice corvette) and drove to Jax and back. I got out my multimeter and measured the voltage at 12.8 then I went and turned the radio on and I watched the voltage slowly drop to under 12 volts, It managed to start up and I measures around 14 volts consistently. Had the battery tested and volts read good but it failed the load test. Replaced battery and it started up quick and strong and seemed to regain the low end torque I thought I was loosing lately. I dunno if a faulty or old battery can actually effect the torque curve enough to be noticeable but I surely felt something healthier with the new battery, still could have been a ghost feeling tho. Just go get the battery tested because the voltage may say its fine but the amperage can be deceptive based on a voltage reading. Most places even have an alternator tester.
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I agree that there may be something wrong with your charging system. Once you get it started, the alternator should be handling all the eletrical demands as well as charging the battery. The battery is primarily used to start the car. An autoparts store should be able to test your entire sytem. Dont forget to take a good look at your cables. You could have a bad connection or a cable thats deteriorating and not passing enough amps to do the job. Good luck!
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