13.4-13.9V at the alternator is normal. for a Vanagon, from my experience.
Other cars seems to go up to 14 or 14.5V but not Vanagons.
Are you sure there's nothing draining the battery?

Thomas Brobst
Accu-Sort Systems, Inc
Staff Mechanical Design Engineer
215-721-5061
fax 215-799-1600

If we knew what it was we were doing, it would not be called research, would it? -Albert Einstein