Doesn’t sound like your charging at all. Not sure if the regulator is serviceable on that alternator.

Never mind I looked it up, it is. $40-$60
I’d probably just change the whole alternator and call it done

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero