Battery empty despite always on charger

[curious]

I would like to have my dashboard displayed continuously.
Allthough both an Ipad and a Galaxy tab are connected to their chargers they don't make it till the end of the day.
Amongst some swithes the fIrst screen has the view of a camera and 'buienradar' .

Do you have any suggestions to use less energy ?

Both tablets are not the newest and lower brightness did not help

[SweetPants]

I have an old Nexus 7 connected 24x7 with it's charger for several years now. When i do not use it i switch the tablet off or let it switch off after several minutes not used. You could try a 'heavier' charger or maybe remove the battery, but i'm not 100% sure it will run without.