If your alternator isn't cranking out the charging voltage like it used to, don't rush out and replace the whole thing. You may just have a worn out voltage regulator. This little part has contacts that wear out over time, and when they do, the voltage drops off significantly, and even entirely. We always carry a spare with us in our vans because they are small, cheap, and simple to replace with hand tools. Brand varies depending on availability.
Fits: All 1980-91 Vanagon.