3rd gen electrical problem :( help? Alternator?

[4FordFamily]

Ok so while driving, I had my stereo on (nothing big, maybe 400-500 watts) and my capacitor was making the "low battery" noise. (a ringing) (capacitor wired in to the stereo).

So I looked down, and the battery gauge was about 1/4 the way up (from L). I quickly turned off the stereo, and left my headlights on. (sort of dark) It was holding steady for about 2 minutes, (while the ABS light came on during braking... related issue, never seen this before?) then started dropping slowly to 1/5 the way past Low. (when 1/5 or lower the battery light turned on) Turned the head lights off. for 2 more minutes, it jumped back to 1/4... then right before I got home (after driving 2 minutes with NO electronics whatsoever on... the gauge popped right back to normal... and held there until I parked.

Then, I hit the gas to see what happened, and it shot it back down (instead of charing) to 1/4 gauge or slightly lower.

My capacitor reads out a 9.6-10 volt power, 10 volt when it was "normal" after it miraculously "fixed" itself. then 9.6 or so when it "messed back up".

Alternator?

It's wierd because very little to no abnormal smell... maybe a little but I could have been smelling things... and NO whining noise when accelerating or anything...

I just bought this damn truck, and bought it to replace my 1995 that i just spent 2500 fixing in 2 months

 

[Tbars4]

...I would suggest getting the battery and the alt bench tested to see if they are now failing due to another problem...

...I think your problem may be with your alternator wiring or battery cables though...I would also look into your stereo wiring and make sure it's proper...

 

[Hitchhikingmike]

...I would suggest getting the battery and the alt bench tested to see if they are now failing due to another problem...

...I think your problem may be with your alternator wiring or battery cables though...I would also look into your stereo wiring and make sure it's proper...

 

[4FordFamily]

...I would suggest getting the battery and the alt bench tested to see if they are now failing due to another problem...

...I think your problem may be with your alternator wiring or battery cables though...I would also look into your stereo wiring and make sure it's proper...

Well, I bought a new battery... same problem.. At first all was well... i turned ALL my electronics on including stereo after I let it idle for 30 mins... then drove around.. seemed ehh ok. got a hair below half way mark on the gauge... then in 15 mins it sloowly went down to 1/3 and 1/4 the way... and then got so low I couldnt start my truck.

Then, i turned it on after about 60 seconds, and it fired up right away... the terminals were fine... it has to be the alternator.

The wiring is fine, i double checked it.

 

[FourXFred]

My alternator in my 02 4.6 went bad a few months ago, and it was similar to this. The thing would die, then miraculously fire back up to life for a few seconds, then die again. The alternator isnt hard to do on the V8 (not sure if you have the V8 or not) as it is right on top. The difficult part is getting the stupid belt off (i had to remove the bottom of the fan cage to get the socket in there. soooo much swearing involved). There are two different alternators that fit the truck, and both will work, but the wrong one will leave the battery light on even tho it is charging fine.I discovered that the hard way. I suggest pulling the alternator off and bringing it down when you get the new one to verify it is the correct model. Good luck, and say goodbye to about $200.