I have an email from Ken Ehalt of New York. He had gone to Germany in the early 1960's and met a priest who knew the Ehalt name. He related it to a "fine Bavarian family." While in the town of Berchetsgarden, he came across the name in an old hotel and asked someone what it meant. He was told it means "keeper of the grains". The grains were used to make beer.
I don't know much more other than Ken did give me a phone number and said there was more. This email was from 1998!