Taurus Charging Problem - stange

My 1997 Taurus has symptoms like a bad battery or alternator, yet I've replaced them both and still have the problem. The battery isn't charging and won't start the car, especially after driving the car for
a while. A jump will get it back up to where it will start. Also, if the car sits for a while it will start. But when running, the headlights are bright and there seems to be enough power.
Any suggestions?
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snipped-for-privacy@nc.rr.com wrote:

DOHC duratech engine?
--
Yeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price
you pay..DEAL with it!
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Plain 3.0L EFI engine.
Battery voltage - not running, blower and lights on high = 11.9V. Battery voltage while running 14.6 V. I can't measure current draw easily. Started cold this am fine w/lots of cranking power. Belt seems fine, battery cable connections clean and tight.
Maybe a hot start issue?
Keith
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" snipped-for-privacy@nc.rr.com" wrote:

Fully charged battery at rest after a few hours, no draw = 12.66 volts
Alternator is producing normally, almost certainly bad battery (probable dying cell).
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snipped-for-privacy@nc.rr.com wrote:

    Place one lead of a voltmeter on the negative battery terminal, and the other on a good ground point on the engine. Check to see if there is a voltage drop across these points WHEN the engine is cranked. If there is, there is a corroded (poor) connection for the ground cable. Do the same for the positive lead, only use the starter battery terminal instead of ground and the + battery lead. The same thing applies should there be a voltage drop of any substance.
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snipped-for-privacy@nc.rr.com wrote:

    You are going to need to take some measurements. What is the voltage on the battery terminals while the car is running? How much current is being drawn from the battery while the car is off?
    Is the belt for the alternator loose? Are your cables to and from the battery clean and tight?
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snipped-for-privacy@nc.rr.com wrote:

Turn on the head lights when it won't start. Are they bright? Now, crank the motor with the lights on. DO them dimm a lot when it won't crank over?
CHeck the ground from the battery to the engine block. If the battery cables look suspicious, replace them.
I had a bad solenoid on my 93 which caused an intermittent no start. It was a cheap rebuilt.
Bob
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I'm going to make a wild guess and say bum battery cable or ground. I had a cable die once right where the cable entered the clamp. It looked perfect but caused symptoms like you describe. After I replaced both battery cables I peeled back the insulation and found heavy, heavy corrosion. A good tug seperated it completely.
You may also be seeing the signs of a dying starter, they get weaker if they get hot. I'd check, or even better, disconnect all battery type cables, clean, and reassemble first. Starter failure doesn't happen like that much anymore.
Hope this helps! PoD

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It was the starter. It seemed to run okay off of the engine but sounded funny. Took it to AutoZone and they put it on their tester and it PASSED! But the guy said it sounded weak, and it did, compared to a new starter which we also tested. Got the new starter and that solved the problem.
Keith
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