87 GT alternator voltage question - battery drain in 12 hours
01-01-2010, 12:36 PM
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87 GT alternator voltage question - battery drain in 12 hours
Hi Guys....
Quick question... My 87 GT has some sort of an electrical problem, where the battery will drain in less that 12-16 hours, so I have to have it connected to an AC charger to prevent the battery from draining when the car is in the garage overnight... I think it might be the alternator? With the car off, the battery reads 13.3 volts because I had it connected to the charger over night. But... When the car is at idle speed (750-800rpm with no lights on or any accessories), the voltage shows 16.5 volts when I connect the multimeter to the positive and negative terminal posts on the battery. Is this voltage where it should be on a good alternator? What else can be draining the battery. The 87 is 100% stock. No alarm system, radio off, no lights on, etc..... I guess I need to start pulling some fuses, but the alternator is original, 23 year old unit. Bit rusty, so I thought that I'd start there.. Also, on 87 5.0 HO motors, were the original alternators 65 amp or higher? Can I get it replaced with 75 or 95 amp alternator without the rist of frying anything? Sorry for all these questions, but I'm a bit of a newbie around Fox Stangs. Any suggestions would be appreciated. Thanks in advance.
Martin
Quick question... My 87 GT has some sort of an electrical problem, where the battery will drain in less that 12-16 hours, so I have to have it connected to an AC charger to prevent the battery from draining when the car is in the garage overnight... I think it might be the alternator? With the car off, the battery reads 13.3 volts because I had it connected to the charger over night. But... When the car is at idle speed (750-800rpm with no lights on or any accessories), the voltage shows 16.5 volts when I connect the multimeter to the positive and negative terminal posts on the battery. Is this voltage where it should be on a good alternator? What else can be draining the battery. The 87 is 100% stock. No alarm system, radio off, no lights on, etc..... I guess I need to start pulling some fuses, but the alternator is original, 23 year old unit. Bit rusty, so I thought that I'd start there.. Also, on 87 5.0 HO motors, were the original alternators 65 amp or higher? Can I get it replaced with 75 or 95 amp alternator without the rist of frying anything? Sorry for all these questions, but I'm a bit of a newbie around Fox Stangs. Any suggestions would be appreciated. Thanks in advance.
Martin
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