Apple has added numerous battery-management features to the iPhone over the years. Despite the common belief that closing unused apps saves power, it actually does not. Background apps are not the primary cause of battery drain, but limiting their power draw when suspended can help. The Background App Refresh setting, when enabled, allows apps to update themselves even while suspended; turning this off saves power. Similarly, under individual app settings, location access can be restricted to only when the app is in use.
Apple recommends managing brightness as the first step, either manually setting it to the lowest level or enabling auto-brightness. Keeping Wi-Fi turned on is also advised, as cellular connections use more power than Wi-Fi. Beyond brightness, disabling Always-On Display and enabling Dark Mode can save power, especially on OLED screens. Turning on Limit Frame Rate sets the display to 60 Hz instead of Pro Motion's 120 Hz.
The iPhone includes settings to change how it handles charging and power draw. With Adaptive Power on, the phone analyzes usage patterns to lower battery drain when full power is not typically needed. Low Power Mode forces similar changes but has a heavier performance impact, best used only when necessary. With Adaptive Power enabled, Low Power Mode automatically engages at 20 percent battery. Optimized Charging prevents wear by stopping charges at 80 percent until needed. Users can also set a custom charge limit to avoid filling to 100 percent, which can reduce battery life over time. Keeping battery charge between 20 percent and 80 percent, rather than fully draining or filling it, can extend the battery's life noticeably.
Source: Engadget · Summarized by HeadlinesBriefing