Not sure if you started car....
The stock OEM charger that comes with car is enough to keep the battery going. Not sure if your using that or Battery tender jr, with lighter attachment.
If you dont have Ford OEM chrager some dealers here can get it with zippered pouch for $80.
In addition, it can used with windows up, and can be left against rubber seal at bottom of door, with door closed. Its 20 ft cord is also handy.
Someone here had in on the car for 3 yrs straight with no problem.