Maximum Capacity is at 98% in less than 2 months on iPhone 16 Pro

Iphone 16 Pro Max, Battery health 100%, 28 cycles.

Always charging up to 90% and don’t let it drop less than 20%

I have an iPhone 16 Pro Max and have been using it since release day. I have the Always on Display enabled and I try to keep it between 95% and 15% as much as possible, but sometimes I let it charge the whole way up overnight and once I accidentally let it completely die while working. I’m actually surprised it’s held up this well so long. Its 100% capacity has lasted longer than any prior iPhone from my personal experience. There definitely seems to be some luck of the draw involved, though.

This is not an answer to your original question.  I have noticed your use of your phone has an unusual Activity being used in one particular App.  The ‘’Home and Locked screen” App;  Has an extraordinary amount of use.

I use my IPhone 16 PMax for a few hour a day.  And my Locked Screen use is a few minutes.  Maybe an average of 4-5% per day.  Yours is over 2 hours use when the phone is locked.   I am not an expert.  But, you might have some settings that might be helpful to reduce this particular issue,  And possibly the amount of “Dynamic Island" features, Live Activities that are active when your phone is locked.

After doing some additional research, my opinion is that this is not normal for an iPhone 15 battery, which Apple claims will go up to 1,000 cycles before it reaches a Maximum Capacity of 80%.

"Batteries of iPhone 15 models are designed to retain 80 percent of their original capacity at 1000 complete charge cycles under ideal conditions.*"

iPhone battery and performance - Apple Support

That would translate to a 1% decline for every 50 charge cycles. We've been making the mistake of assuming that the old guidelines........a 1% decline for every 25 charge cycles.....applies to the iPhone 15 (and iPhone 16).

The wild card here is that Apple also states......(in the hard to find footnotes).....That these numbers are based on "ideal" conditions, so the easy way to explain that the battery is declining at a rate faster than the claims would be to state that the iPhone must not be operating under "ideal conditions".....whatever they are. I can't find anything that details or defines "ideal conditions".

Its been more than two month of usage.

I have iPhone 16 Pro, Battery health is 100%, 108 cycles.

I personally charge it up to 80% and try not to let it drop below 20%

The issue is lithium ion batteries do not decline in a pure linear fashion. It’s entirely possible it’ll decline just 1% in the next 100 cycles.

Apple will run diagnostics and if nothing is showing as defective, I doubt they’ll do anything. The 4% decline is unusual, but I don’t believe is indicative of a defect. But in any event, diagnostics is the next step.

Lithium ion doesn’t age in a linear fashion, it may hold at 90% for 6 months. This is well documented use issue with lithium ion batteries. Below are 4 different charge voltages and look how the batteries aged. Only 1 out of three aged linearly and this was under laboratory conditions so in real world would be hard to duplicate.

Battery life, how long an iPhone lasts on a single charge and is what I see mostly being complained about here, is a different issue from battery health. As has been said already, the iPhone 16 is far too new to have any data on how fast the battery will degrade, though I don't expect it to be significantly different from previous models of iPhone.

As to how long your battery lasts on a charge, there are some tips here:

If the battery in your iPhone drains too quickly - Apple Support

Regards.

Remember that Apple always rounds down any "tenths" in the Maximum Capacity display to the nearest whole number.

For example.....98.9% will display as 98%, even though the battery is only one tenth below 99%.

So the battery display may have dropped from 100% to 98.9%, a drop of only 1.1%, but this will look as if the battery dropped 2% from 100% to 98%. Significant difference there.

It's just way too early at this point to try to estimate how long your battery might go.

At a cycle count of 200, chances are the battery will be at about 92%. At 375 cycles, the battery will in the 85% range.

If the battery is really defective, and drops below 80% in the first year, Apple will replace the battery at no charge.

Batteries, like people are individuals. No two people age exactly the same and batteries don’t age the same either. The exact usage, chemical makeup, storage conditions, exposure to heat and cold and about a dozen other factors mean that every battery ages differently. Battery aging is not a linear (straight line) and degrades at different rates as the chemicals in the battery age and other factors mentioned above. Apple expects your battery health to be at 80% after 24 months. If your battery health misses that expectation, contact Apple Support.

Please review the Apple Support articles on battery optimization. It contains the best current practices for battery charging.

iPhone Battery and Performance - Apple Support

Batteries - Maximizing Performance - Apple

About the battery and performance of iPhone 11 and later - Apple Support

Im at 331 cycles and 98% now i only charge phone to 85% and dont let it go down past 25% also dont use the low battery mode and i also keep my phone on dark mode.

My 16 Pro's battery is only over provisioned by about 1.6%. A surprisingly small ammount. Usually manufacturers place a 5% over provision in the batteries so that even when you buy a phone that's been sitting on a shelf for six months. It'll still have the full rated capacity This reply is not looking for advice or feedback . I am simply adding information.