The recommended time to change an iPhone battery is when its battery health percentage drops to 80% or below. Apple states that a normal battery retains up to 80% of its original capacity at around 500 complete charge cycles, and when it falls to 80%, iOS typically shows a warning about significant battery degradation. At this point, replacing the battery will restore full performance and capacity. Additionally, if the battery life feels insufficient for daily use — such as running out of charge too quickly — it is a practical sign to change the battery. You can check your battery health on your iPhone by going to Settings > Battery > Battery Health. For safety and quality, it is recommended to get the battery replaced by Apple or an authorized service provider using genuine parts. Replacement by untrained technicians or non- genuine parts can cause performance issues and safety risks. In summary:

• Replace when battery health reaches 80% or lower.
• Replace if battery life is unsatisfactory to daily needs.
• Apple recommends professional replacement for safety and performance.

This guidance typically means battery replacement after about 2-3 years or 500 charge cycles of average use, though heavy usage may shorten this timeframe.