[wiswind]

I would agree with the in-vehicle test of the battery and alternator.
In my '96, there was a fuse "T" for the alternator that........if blown, you will not get any charging.
I do not know if that was removed in the newer windstars......or what year it would have been removed.
Someone had posted a while back that they did not use this fuse in newer windstars.

Check the alternator ground to the chassis ground also.
Look for any signs of a burned connector........a loose crimp connector can look great on the terminal end, but be burned out inside the crimp to the wire.
Do this on all the connections.....including the battery, and ground connections......as well as the big power/ground connections on the back side of the power distribution box in the engine compartment (with all the relays inside).