how to keep 100 battery health

All batteries deplete with use and over time. Apple batteries usually last about 2 years with normal usage. You haven't mentioned your Battery Health Figure, but when it reaches 80% you should make an appointment at the nearest Apple Store for Battery Replacement.

Apple Store - Find a Store - Apple

katieee22 Said:

"how to keep 100 battery health: In just two weeks my battery health keep going low i don't know what to do anymore"

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For reference...

Troubleshooting iPhone Battery Draining:

A. Battery Drain Info:

The iPhone battery will drain, unless it is plugged in and charging. With lots installed, the charge would be slower. As for how fast it would drain the battery, that would depend on the battery health and the volume (sound) you use.

1. Go Here: iPhone Battery and Performance - Apple Support
2. Scroll Down: to "Your battery's maximum capacity"

B.. Troubleshooting the Battery:

• iPhone Battery and Performance - Apple Support

• Charge and Monitor the iPhone Battery - Apple Support

• About the Battery Usage on your iPhone - Apple Support

• About Optimized Battery Charging on your iPhone - Apple Support

• If you see "Your iPhone Battery may Need to be Serviced" - Apple Support

• Use Low Power Mode to Save Battery Life on your iPhone - Apple Support

C. Did this Occur After an Update?:

Give Apple Feedback:

Do your Part: Provide Apple with feedback on this, letting them know about this issue.  Apple may not get back to you directly, but the more feedback they receive on this, the more they will know what is occurring, and what bug fixes to include in updates to come.

1. Go Here: Feedback - iPhone - Apple
2. Select: "Bug Report" for the "Feedback Type"
3. Comment: that this all began after installing an update. Include the URL of this post
4. Proceed from there as necessary

katieee22 Said:

"how to keep 100 battery health: In just two weeks my battery health keep going low i don't know what to do anymore"

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About Battery Health Percentage:

Unfortunately, there is no way to determine why, nor when, the Battery Health decreased. I've have my iPhone for 2 years now, and it's only down to 97%. Its in use when on then go. It's alll just a guestimation on Apple's part. I've even seen mine increase at times.

What are you calling “low” … 99% ?

If so, that’s normal.