Regulator gone bad?

Our optima on the Jensen required easily 24 hours on a 5 amp battery tender smart charger to get the charger to claim "fully charged".
We have a new tuff stuff 1 wire alternator @ 100 amps or so.
Car batt was dead from sitting a few weeks (left the key in acc).
I jumped the car and drove it for about 30 minutes and the battery was still completely dead. I called optima and complained. They insisted I use a smart charger and let it charge slowly for at least 24 hours. I did, and it is 100 % fixed.
Since then (a year ago) it has sat for a month or more with zero issues. Cranks over like a son of a bich with the original starter.