Over time, the battery’s capacity decreases, leading to shorter usage times between charges. You might need to replace iPhone battery if you notice any of the following signs:

1. 1. Slow Performance:
      An aging battery can cause your iPhone to slow down, especially when performing tasks that require more power you will withness some kind of glitch on the phone screen.

1. 1. Short Battery Life:
      If your iPhone doesn’t last as long as it used to on a single charge, even after reducing usage or turning off power-hungry features, the battery might be wearing out.
   2. Here are some factors that can contribute to shorter battery life:
      

       

      • • Battery Age: As batteries age, their ability to hold a charge diminishes. After a certain number of charge cycles (usually around 500 to 1000), the battery’s capacity can drop significantly, leading to shorter battery life.
          

           

          • • Usage Habits: High usage of power-hungry apps, frequent video streaming, or gaming can drain the battery quickly. Similarly, poor network coverage or constantly searching for a signal can also impact battery life.
          • • Background Apps: Apps running in the background can drain the battery, especially if they are using location services or refreshing content frequently.
          • • Screen Brightness: Keeping the screen brightness at a high level can drain the battery faster, especially on devices with OLED displays.

1. 1. 
      Unexpected Shutdowns:
      If your iPhone shuts down unexpectedly even when it has a charge, it could be a sign of a failing battery. Extreme temperatures, both hot and cold, can affect battery performance. Avoid exposing your iPhone to temperatures outside the recommended range (0° to 35°C or 32° to 95°F)

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   1. Battery Health Indicator:
      Checking your battery health regularly can give you an idea of how much capacity your battery has lost over time. If the Maximum Capacity is significantly below 100%, it may be time to consider replacing the battery. Check your battery health in the Settings app under Battery > Battery Health. If the Maximum Capacity is significantly below 100%, it’s a sign that your battery is degraded.

1. 1. 
      Physical Damage:
      If the battery is swollen or damaged, it should be replaced immediately to avoid safety hazards. You will have signs such as over hot back of the phone which is an indication that is time to replace iPhone battery

Sometimes, software updates can lead to battery drain issues. It’s a good idea to keep your iPhone’s software up to date, as newer updates often include optimizations for better battery performance. It’s recommended to have your battery replaced by a good technician, especially for iPhones with sealed batteries like recent models.