Apple battery health has dropped to 77%. Do you need to replace the battery?

Yes When the battery capacity is less than 80% of the original capacity, the battery should be replaced.

Users can judge whether their batteries need to be replaced according to the suggestions in the iPhone system: any iPhone that has been updated to iOS 10.2. 1 or above can go to the Apple direct store to replace the batteries as long as the prompt "iPhone battery may need repair" is seen in the phone settings-battery options.

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Note: Correct battery charging and use: You can charge the battery whenever possible. If there is a power supply, the mobile phone can be charged at any time as long as it is not 100%. However, it should be noted that when charging, try not to use the mobile phone, especially when answering the phone. If used, the battery activity of the mobile phone can be maintained to a certain extent.