We have several Mustangs, this is my Daughters Car.
2019 Mustang GT full options goes into battery saver mode after sitting 4 days.
I have put in a battery tender when car is not in use.
It is common for the card to sit for 3-7 days without use.
Car was sitting for 4 days and on iphone Battery saver mode came up.

Any suggestions on a better battery tender that would prevent "Battery Saver Mode" to come up?