Alternator

Since installing the 2nd battery I've been hearing a whine at 2-3000 rpm, which sounded like it was coming from the alternator. Similar to the whine of a low power steering pump. I took it in to the local rebuild shops. They said it was the Stator, which is a common occurrence when 2 batteries are installed. They checked the charging system and proclaimed it was in fine fiddle, so now I just have another new sound to put up with...