My iPhone battery capacity is grainy

No, you cannot increase the battery capacity.

Phone batteries, like all rechargeable batteries, are consumable components that become less effective as they age. You should change out the battery once your Battery Health reaches below 80% which will take over 2 years to reach under normal usage. Until then enjoy your iPhone.

Here is some more reading on an iPhone battery and its performance ➡️ iPhone Battery and Performance - Apple Support

Axel F.

Hello asareisaac!

No, you cannot. Please go to: Settings > Battery > Battery Health & Charging. Now, please view the Maximum Capacity, and tell us what it’s at.

Apple recommends that you have your battery replaced, when the battery’s Maximum Capacity reaches 80% or lower. When the time comes, please see: iPhone Battery Repair & Replacement - Apple Support.

I hope this is helpful. Good Luck!

asareisaac Said:

"My iPhone battery capacity is grainy: Can I increase my battery capacity"

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About Battery Health:

No. You cannot increase the Battery Health percentage. And, unfortunately, there is no way to know why, or when, the Battery Health percentage decreased.

asareisaac Said::

"Will the replacement of the battery be 100%"

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About 100% Battery Health:

Actually, the Battery Health can increase. It's all just a guestimation on Apple's part. But, I've never seen any reports of it being above 100%, even though it can increase on its own.

Time to replace it.

iPhone Battery Repair & Replacement - Apple Support

Wow! Thanks for letting us know! Make sure to get it replaced!

Hey there!

Because it’s a battery, I guess! To learn about Apple’s explanation for this, please go through: iPhone Battery and Performance - Apple Support

You are likely 6-12 months overdue for a battery replacement. Tap / Click the links above for more info.

Yes, for a month or two before it starts to decline.

Why does the battery decline

It is what batteries do. No way to avoid that.

Read here -

https://www.engineering.com/story/why-do-good-batteries-go-bad