iPhone 5S Battery drains too quickly on standby & Phone not charging / entlädt die Batterien - YouTube
Why does my iPhone 5s battery suddenly drop from 43% to 20% and then 10% suddenly? Is this battery to be replaced or is there something other malfunctioning? - Quora
9 Tips] Does iOS 16 Drain Battery Fast? How to Fix?
How to Fix the Battery Draining Issue on Your iPhone After Updating to iOS 6.1.3 « iOS & iPhone :: Gadget Hacks