ok here is the deal, 2 year old alternator 20k miles on it, brand new battery and new cables nothing loose or coroded.

start car up alternator charges 14.4 slowly dips down to 13.8 then right down to 12.2-12.6 Amps also drop with voltage. If i idle the car up it will go up in voltage, it causes my heater/headlight to dim and go up.

My impression is that the alternator is dying, weak field or the regulator is going out.
What do you guys think?

battery light comes on what ignition is turned on, then goes off and stays off when car is running and does not come on, so the alternator is putting out something just not enough sometimes.

 

Replace it Or get it rebuilt.

 

sounds like the regulator

 

Does your voltage fluctuate when the fans turns on. If so you may have the same problem I was having with the fan control module. Was pulling to much amp and causing voltage to go down to 11 v Then Back up.

 

No I don't have that fan anymore or the control, nothing turns on the amps on the alternator slowly back down to 1 from 25, then if u go 1100 rpm it acts fine until you release and let it idle

 

So you don't have a cooling fan? Fan control module controls the cooling fan. But if you say you don't have that then you sound like your alternator

 

If the fan kicks on it should dip then regulate out, but in any case i had a spare alternator core so I want to my alternator/starter guy and talked to him about it and he looked at it and said it's a bad winding, heats up and slowly drops. Bad insulation.
So any way I told him I wanted this core to be upped to 160amps (big stereo and seems like everyone wants a 160amps alternator now) he said no problem be done in a day $90 bucks said and done.