alternator doing strange things

[mustang347]

I drove to the car wash sunday and everything was good...vacuumed my car and dried it off and went to start it and it was dead. I havent had any battery issues whatsoever. I jumped it and headed home to put it on the charger. once i got there it started right up. I changed the battery yesterday after the test came up weak. I have since been watching the volt gauge and it dances between 12.8 and 14.4 randomly. i know these cars have "smart charging" but i am wondering if i need to change the alternator now. 19 GT PP1 401A 10 speed car with 43000 miles. i did a search and found alot of bad alternators on the gt 350's but didnt really see much about the normal GT's

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[StangTime]

I think it's ok. Mine does the same thing. I will occasionally see >14 volts once in a while.

 

[1MeanZ]

Mine does the same thing with charging voltage, you likely had a bad battery.

 

[HiTekExec]

I drove to the car wash sunday and everything was good...vacuumed my car and dried it off and went to start it and it was dead. I havent had any battery issues whatsoever. I jumped it and headed home to put it on the charger. once i got there it started right up. I changed the battery yesterday after the test came up weak. I have since been watching the volt gauge and it dances between 12.8 and 14.4 randomly. i know these cars have "smart charging" but i am wondering if i need to change the alternator now. 19 GT PP1 401A 10 speed car with 43000 miles. i did a search and found alot of bad alternators on the gt 350's but didnt really see much about the normal GT's

Sounds like just a bad battery. When you say it tested weak, how did you test it? A test of the charging system would indicate if the alternator was acting up.
The battery management system benefits the alternator by keeping output optimum to load; which means that you can't use the old 14.1v at the battery to see if the alternator is operating correctly, and yes, when driving the voltage will vary depending on the load you are enabling (RPM, lights, accessories...)

 

[mustang347]

one of my mechanics has a battery load tester and it read 566 CCA when it is rated at 590 so he said its not actually bad but its weak

 

[HiTekExec]

one of my mechanics has a battery load tester and it read 566 CCA when it is rated at 590 so he said its not actually bad but its weak

Probably was just the battery; I wouldn’t replace the alternator as it is obviously supplying back to battery and the battery management system. I was initially more keen on the the dead after washing, then saw the battery replacement.

 

[Roger Blose]

FYI, if your car has the heated seats, then your car has a 200 amp factory alternator according to the Ford Racing catalog.which is pretty cool.

 

[mustang347]

FYI, if your car has the heated seats, then your car has a 200 amp factory alternator according to the Ford Racing catalog.which is pretty cool.

it does have heated and cooled seats

 

[1966 2+2 289]

I have a 19 Bullitt with only 7400 miles, the battery has gone dead and needed a jump start 4 times in last 18 months. took it to the dealer and had the electrical system checked. The dealer says the system is working as designed and the battery is good. I now keep jumper cables in the car at all times and purchased a small charger to keep it at full charge. I suspect that the car has a small battery a lot it of items that drain energy when the car is not moving. Just another fact of modern high tech.

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