charging/ alternator issue

[19 tahoe 97]

on Tuesday night I noticed that my dash lights seemed a little dim so I looked over to see that my battery was only being charged at 10-11 volts and the dash light for the battery came on. I kept watching it and after a few minutes it went up to around 13 volts. it has always charged right at 14 volts as it should before then. I put only about a hundred more miles on it up through today since then and up until this morning it had been charging around 12-13 volts. On the way to work this morning it held steady at 14 volts like normal which it hasn't done since the beginning of the week. On the way home it was down to charging around 12 volts again. When I stopped at a red light it dropped slightly below the 12 volts it was at and the battery light came on again. when i took off it moved back up to 12 volts and the light went off. the same thing happened again when I pulled into my driveway 2 miles up the road.

this leads me to believe that it is the alternator because it charges a little better when the truck is moving although from my past experiences I have never seen a failing alternator work properly on and off, they usually just slowly charge less and less and do not work much at all after a day or so. This is a '97 tahoe with almost 200k. Any help is appreciated.

 

[Donnie Yukonie]

Moved this to the appropriate section , you will get better feedback .

The alternator will pull more volts at higher RPMs yours is probably on its way out

 

[19 tahoe 97]

Thanks

 

[SunlitComet]

unless you can verify a slipping alternator the regulator or brushes inside are going out on you.