Alternator issue

[Bking99]

battery gauge started reading high a few months ago and over time kept getting higher and higher. Now it’s just below the red. Tested alternator and said bad diode. Replaced it with a new one and the new one is doing the exact same thing. High reading on the gauge. If I push and hold the window switch it goes back close to normal but still higher than it used to be, let it go and it goes up again to nearly in the red. When I replaced the alternator, I swapped the whole unit. They didn’t rebuild mine so it’s hard to believe it would still be the alt. That would be a hell of a coincidence. The meter at the place that tested it said it was rippling around 33-35 range. Any help would be appreciated.

 

[joe moe]

dead cell in your battery maybe

 

[Later2u]

Perhaps a weak cell in the battery. Good to verify the battery is fine anyways.
I had a dead cell in a battery recently, stared fine in the morning, start it to go home, no deal. Dead cell.
Couldn't even jump it to start.