1979 Volkswagen Van Smoking Alternator

I just got my 1979 vw transporter bus out on the street for the first time after installing a new alternator and new battery.I had bought it after it had been sitting for about 9 years. I did all the necessary tune up checkups. It idled great when it sat but once it got halfway down the road it started smoking and the battery died. When i looked in the engine compartment to check it out; the wiring from the back of the alternator had been melted and the alternator had been smoking. The alternator belt had also been kicked off. Any ideas on what the problem might be?
-Kenneth