I would test to see if there is a short in one of your circuits that is draining the battery overnight.
Disconnect the negative cable from the battery.
Place a test light between the the cable and the battery terminal.
Insure all doors are closed and any thing else that would illuminate a light or cause an open circuit.
If the test light is illuminated you have a short in a circuit.
To find the circuit responsible, remove a fuse, close the door and see if test light is still iluminated.
There are those occasions when more than one circuit could be the culprit.
On a Grand Marquis I had to remove ever fuse then start replacing them one at a time, with only one in the fuse block at a time.
Hope this helps