iPhone 6(S)/Plus Maximum Capacity In Battery --> Battery Health, Drops Dramatically

[EDLIU]

I have an old iPhone 6 Plus(iOS 12.3.2) that I seldom use. The "Maximum Capacity" in Battery --> Battery Health, drops dramatically from 95% to 91% then to 90% recently.

Why is this happening? Is there any problem with my iPhone's battery?

Thanks.

 

[I7guy]

All li-ion batteries deteriorate with age and use. Maybe get the battery replaced if the phone is a backup.

 

[Newtons Apple]

Dropping 5% is hardly “dramatic”.

These battery programs are not that good a what they are supposed to do.

 

[tonybarnaby]

The battery is around $60. I'd assume the phone is worth $200 or less. If you don't use it much I'd let it go.

 

[now i see it]

Ignore it.
When you NOTICE that the phone doesn't last very long compared to how it used to, then take a peek at it. Ignore it until it hits 80%. Then you can consider a battery replacement