battery maximum capacity

Expect Battery Health to decline an average of about 1% a month. That's an average. Some months it will not decline at all, and other months it might drop 2-3%.

My phone is about a year old. Battery Health is 89%. Right on schedule.

Whenever you install an iOS update, this will really make the battery work hard for a few days, then things will settle down.

2 years is about what to expect for a battery. Replace it when the Health is down to 80%.

Your battery does seem to be declining faster than average. But.....Apple will not do anything unless the battery declines to 80% while the phone is still covered by AppleCare. In that case, Apple will replace the battery free of charge.

Otherwise, I am afraid that there are no magic settings, tricks or tips that will have any positive measurable effect on your battery. In fact, I would be suspicious of any claim that promises to improve battery performance.

It is hard to say. It depends a lot on how often you charge your iPhone. The more charging to 100%, the more the battery wears out. My iPhone is from November 2022, and it currently has 96% Maximum Capacity. I thought 30% in 1 year sounds a lot - but not impossible if the phone has really been used, and charged, used and charged - and often connected to the charger, even if the battery is charged to 100%

Apple recommends that the battery be changed when the maximum capacity is 80%.

You will also see this screen below when it's time:

You can find much more useful information here:

iPhone Battery and Performance - Apple Support

It again depends on how it is used. But do you notice that your battery life has deteriorated? - it's not because you don't have to pay attention, but I experience many who get hung up on the numbers in Maximum Capacity. If your iPhone works, forget about that menu, and remember that if something goes wrong with your battery, you have a product warranty - how long it covers depends on where you are in the world and on what conditions the phone is bought.

With 8-9 hours of use, it doesn't necessarily seem unrealistic. Remember that after an iOS update, there may be increased battery consumption, as files are moved around, changed and deleted. This may, for a period of time, result in a higher battery consumption. You may also find that your iPhone gets warmer. If it continues and your iPhone continues to rapidly go down in Maximum Capacity and your battery life does not improve, contact Apple again. Until then, I would lean on their explanation and say it is more or less normal.

If an iOS update improves battery life, it will be after some time. To begin with, an update will most often drain the battery faster, for the reasons I wrote in my other answer.

I can't get any closer. I am a user like you, and cannot "trump" a battery change through Apple for you. But I agree with you that if you continue to have poor battery life after some time, you should contact Apple again.

You are welcome. No problem, I didn't feel that. I understand that it can be frustrating when a new iPhone for a lot of money does not live up to expectations. Been there, done that.