• If you've ever noticed that your phone's batterydrops from 60% to 50% in a matter of minutes, only to stay at 50% for what seems like an eternity, it's likely time to calibrate the battery.
• Batteries degrade naturally over time, and their capacity gradually diminishes. However, your phone isn't always accurate in this regard—if your battery has declined to 95% of its original capacity, your phone may still show it as 95% full rather than 100% full (the 'new normal').
• Allowing the battery to go from entirely full to completely empty on a regular basis might harm it and reduce its capacity over time. On the other hand, leaving your phone plugged in when it's totally charged can cause the battery to degrade.
• Select Settings > Device > Battery or Settings > Power > Battery in most Android versions. To get a list of all apps and how much battery power they're using, go to Settings > Battery.  Consider deleting an app you don't use very often if it appears to be using a lot of power.
• By tapping it on Android 9, you can observe how power-hungry apps are wasting battery. You'll be able to enable 'Background limitation' for some apps. Keep 'Battery optimization' turned on for all apps.

Read More: Is it normal for a 7% battery to drain in 30 mins?