Does overcharging decrease battery health
iPhone 8 Plus
No. This is because you cannot overcharge the iPhone battery. The charging process is controlled by the iOS (Operating System) and it controls the amount of charge provided to the battery.
Axel F.
An iPhone battery can not be overcharged.
The absolute best thing that you can do for your battery is plug it into the charger and let it charge overnight, every night.
Make sure that you have enabled Optimized Battery Charging as well.
Settings > Battery > Battery Health > Optimized Battery Charging
Battery health
