You can check the health of your iPhone's battery to determine when it's time for a replacement.
To show battery percentage on new iPhone models, swipe down to open the Control Center.
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How to check your iPad's battery health
Open one of your iPad’s analytics files (these files start with “Analytics” followed by a date). In the analytics file, tap the Share button in the upper right-hand corner of the screen. The Siri ...
Is it OK to check your phone’s power bank Can you charge your tablet in the overhead bin? What about a cordless hair dryer?
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