note that those F series ( and probably others too) draw few watts when not used. I can't recall the exact number of watt, but it was kind of high.
Mine last around 1.5-2 weeks not used in summer time.
And winter time, its around 6-7 days.
I ve to use a battery tender.
Here a place where it draw power. and when I noticed that, it was in the morning and it was -21°C (-6°F) on the thermometer !, no sun, under the car shelter. So few watts are lost there.
