What is ideal battery health for iPhone 15 after 6 months of usage?

I'd say you have a very good Battery Health reading! The typical Apple battery will last through 2 years of normal use. Apple suggests that you replace the battery when Battery Health reaches 80%. Check this link...

Batteries - Maximizing Performance - Apple

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

StockstillTiffany wrote:

apple notifications recently notified me that my battery was most optimized at 80ish percent so it stopped charging pass this threshold. ..

You’re conflating the battery health percentage discussed in this thread with optimized charging and the battery charge percentage.

For your case, Apple regulates the battery charging, seeking to reduce the time the iPhone is fully charged.

About Charge Limit and Optimized Battery Charging on iPhone - Apple Support

In addition to other potential power consumption causes, if you’re running iOS 18 on an iPhone 15 Pro or iPhone 15 Pro Max, or on any iPhone 16, Apple Intelligent can consume a fair amount of power.

But all of this is independent of the battery health percentage discussed in this thread.

You are going to drive yourself crazy if you are looking at the Battery Health all the time.

Replace the battery when it is down to 80%, which will be 18-24 months from now.

Nothing unusual with your battery performance in this screenshot or your previous screenshot. It is working exactly as it is supposed to.

My 15 pro max is at 88% after 14 months. I charge it every night because battery gets below 30% and I won’t get very far into the next day at that level.

looking at other posts here my phone seems to be doing a normal digression of the battery.

apple notifications recently notified me that my battery was most optimized at 80ish percent so it stopped charging pass this threshold. Additionally I'm only charging on Mag because new 15 purchase came with defect Cport. My battery typically last 16 hours but I've noticed a drain hugely when synced to other devices such as MacBook. The question will be a question asked for decades to come if Apple exists due to the fact that sync, API's , WiFi , Bluetooth aka iOT exist creating a network for juicing off your device.

Consider whether you bought a battery to monitor, or an iPhone to use.

All batteries can and do inevitably and inexorably degrade.

Yes, most batteries don’t have an estimate of battery health.

When a device battery no longer meets your needs, the battery gets replaced.

Vehicle batteries, for indtance, are routinely replaced after some years of use.

If your iPhone is meeting your needs, then the battery is fine.

MrHoffman wrote:

Consider whether you bought a battery to monitor, or an iPhone to use.

All batteries can and do inevitably and inexorably degrade.

Yes, most batteries don’t have an estimate of battery health.

When a device battery no longer meets your needs, the battery gets replaced.

Vehicle batteries, for indtance, are routinely replaced after some years of use.

If your iPhone is meeting your needs, then the battery is fine.

Some of the best advice I've read about batteries.

I would say around 98 would be normal after 6 months but it depends how you use it. I babied my 15 pro max and it had 170 cycles after a year and it had 100% battery health. My 14 plus before that was down to 95% after 6 months but I didn’t really look after it. 16 pro max now 26 cycles still 100 %

My update: 15 jan 2025 (iPhone 15plus)

Your welcome.