2016 Subaru Forester-3 batteries and new alternator since feb

option man

2016 Subaru Forester-3 batteries and new alternator since feb. 2020...if car is not run in 4 or 5 days, it will not start..battery voltage of day 4 is 11.50 or close to it...it drops overnight to 7 volts or less with car not starting unless charged....HELP!!