Battery percentage
Why my battery percentage decrease fastly?
Question marked as
Top-ranking reply
Every phone and battery are used differently, and as a result if a battery discharges quickly there can be many reasons for it. Take a look at https://support.apple.com/en-us/HT208387 for information that can help. There is also great information about maximizing your battery life at https://www.apple.com/batteries/maximizing-performance/.
If you have an older phone that has been used for a number of years, the battery may need to be replaced. You can see the condition of your battery by going to Settings > Battery > Battery Health. If the maximum capacity is at or below 80%, you'll need to replace your battery.