Regarding the "bargain" battery isolator offered by Princessauto.com, any
unknown battery isolator should be regarded with extreme caution or even
paranoia, especially for use in a Vanagon.

To work properly, the unit must be specifically made for VW / Bosch
alternators.  Any unit claiming to work with all alternators is a sham.

Quality and reliability are also an issue with unknown brands, as problem
units can fry your entire electrical system.

More on this subject soon.  In the meantime pay attention to Haralds
postings on the matter.

Stanley