iPhone 15 battery health dropped to 87% after 313 charging cycles.

313 charging cycles in under a year with 87% maximum capacity is worth keeping an eye on. The number of cycles alone does not determine battery health, because lithium ion batteries age from both charge cycles and time, temperature and charging conditions.

The fact that the percentage drops every few charging cycles does not necessarily mean the battery is losing that exact amount of capacity each time. Battery Health is an estimate, and iOS can occasionally adjust the reported percentage as it recalculates the battery's actual capacity.

Since you are still at 87%, I would not rush to replace the battery. Check Settings > Battery > Battery Health & Charging and look for any service recommendation or message about the battery.

If the percentage continues falling unusually quickly, especially if you notice unexpected shutdowns, overheating or a significant reduction in battery life, I would contact Apple Support and have the battery diagnostics checked. Keeping the phone away from excessive heat is also one of the most important things you can do to slow further battery degradation.

Welcome and thank you for reaching out. 🤗

I am impressed that you managed to lose only 13% in 3 years from its inception, regardless of the charge cycle. That is far above average for a device that is in use every single day since purchase.

Lithium Ion batteries are rechargeable by design.

As part of that design are the electrolytes that hold a charge.

There are allot of steps and various machines that are used to construct a battery.

Between those assembly steps, the batteries are carefully inspected along the way, often in devices used to magnify the various components several times during the production process.

There are various tests to ensure that there are no leaks.

I used to assemble Li Ion batteries.

I can assure you that the failure rate is extremely low.

What you have experienced is normal and expected.

All rechargeable batteries are consumable components that become less effective as they chemically age.

Recent software updates can accelerate that process by adding features that consume more power.

As lithium-ion batteries chemically age, the amount of charge they can hold diminishes, resulting in shorter amounts of time before a device needs to be recharged.

Li Ion (Lithium Ion) batteries have recharging capabilities; however there are limits.

Temperature Effects on Li Ion Battery Life:

• Capacity loss in standby applications is largely determined by temperature
• Annual capacity loss tends to decline as the battery ages
• 80% remaining capacity is generally not the end of a lithium battery's useful life, but recommended by Apple for replacement

I recommend to slow charge your iPhone to maximize the charge capacity, battery health and efficiency. ⚡️🔋

NOTE: Temperature: Charge above -30°C and Discharge below 55°C. Apple won’t replace the battery until it reaches 80% capacity.

Battery Performance Tips:

• iPhone Battery and Performance.
• Check battery health and usage.
• Optimized Battery Charging.
• Maximizing Battery Life.
• Use Low Power Mode.
• About battery usage.
• Show battery percentage.

Click ▶︎ iPhone User Guide. 📖

Good luck! 👋🏼😉

Smiliñ 😎 Brian | Community Volunteer