Charging problem

The first thing that caught my eye was just 12 volts at the battery Jack.
It made me think your battery was real low or has a cell going out.
It should read 12 1/2 volts, sounds like you have it fixed :coffee2:.
But if your battery is about to loose a cell it will work your regulator and alternator allot.
Glad to hear all looks good and up to par :thumbup: