make sure the glove box light isn't staying on There is something drawing down the battery - and a common problem is the door ajar sensors causing the interior lights to stay on. See "Related Questions" below for more about that.
The battery group is 65N for a 2003 Ford Windstar
On the Ford Windstar 2001 model, it is under the hood, next to the battery.
Open the hood and look see.
In the grill area behind the battery
Anywhere from $50 to $150
alternator is not charging battery, or loose - corroded connection on battery cables
The alternator died first and drained your battery shortly thereafter.
On a 2001 Ford Windstar : The Power Distribution Box is in the engine compartment , between the vehicle battery and the drivers side fender
The crank position sensor on a 2001 Ford Windstar van is located on the bottom of the engine. It constantly monitors the engine's crankshaft and reports information to the computer.
Facing the engine from the front of the vehicle, the battery is located in the right, front corner.
The Power Distribution Box ( which is " live " ) is located in the engine compartment between the battery and the drivers side fender on a 2003 Ford Windstar
A slight possibility but not likely