Alternator Or Battery? Need Help

[creektrack]

So I'm pretty dumbfounded right now...thought the regulator was going out on my alternator, but now I have no idea...

So, the other day, I was driving to work in the morning and the battery gauge dropped from about 14 volts to about 10 volts...Battery light didn't come on, so it was still charging, just at a lower voltage, and then about 5-10 minutes later it jumped back up to normal...On the drive home it never happened again...Well, the next day, the exact same thing happened again...

So, I replaced the alternator and my belt, as the belt was pretty worn out, about 3 years old...

Well, fast forward to today, which its been about a week, and it happened again just a couple hours ago, only this time it lasted for maybe a minute...

Can someone please give me any advice here? I plan on going to autozone tomorrow and having them test the battery and alternator...and yes, my battery indicator light does work...thanks in advance

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[COramprat]

Check your connections and make sure they are tight. How old is the battery?

 

[1987stangman]

I would ohm test both the neg and positive battery cables, disconnect them from both ends of course. I would also check the positive cable where it junctions into the fuse block and examine the battery terminal side of the cables (conectors) for the least little bit of corrosion can cause issues.

Didn't see a signature with car year or engine (using tapatalk) so I'm assuming that this a 4.6L powered Mustang?

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[MustangIIMatt]

After checking the wiring, and getting the alternator and battery checked, I'd start looking for patterns for unusual drains.

I once chased a "charging problem" for over a month on my '87 GT 'vert. It eventually ended up being a short in the A/C clutch coil. Being a convertible, the A/C didn't get used much, but when it was, it would drain the battery with the engine running in under an hour. I honestly didn't see the correlation between running the A/C and the battery going dead at the time. I finally figured it out because I had the defroster on while doing a charging test with an old ARBST "Bear" test machine (I miss those things), and when the A/C compressor cycled on, it went from reading 13 volts and positive amperage to 8 volts and negative amperage.

I also tracked down a slow drain in an old Chevy pickup to a horn relay that was staying energized. The contacts in the steering column were making contact, but the owner of the truck had long ago put aftermarket horns in with their own switch and disconnected the original horns. The relay was drawing just enough to run the battery down to the point of making it very sluggish to start since the truck was only driven about once a week.

Should you rule out the alternator itself, the wiring, and the battery, it's time to start looking at the rest of your electrical components.

 

[creektrack]

Well hopefully I can figure this out soon...gonna be making a trip to Austin next week and don't wanna get stuck...

And sorry, the car is a 96 GT convertible, 5 speed with minimal mods

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