Why force-quitting can cost more battery
An app that looks “open” in your phone’s app switcher usually isn’t continuously running. The operating system may pause it in the background, keeping its recent state ready while sharply limiting what it can do. If the phone needs memory for something else, it can discard that paused app automatically.
Force-quitting removes the app from that ready state. When you open it again, the phone may have to launch it from scratch: load its code and data, rebuild the screen, and sometimes fetch fresh information. That work uses the processor and can require network activity. For an app you’ll soon use again, letting the system manage it can avoid an unnecessary restart.
When quitting can still make sense
The tradeoff depends on what the app is doing. A paused game is different from an app actively navigating, playing audio, tracking a workout, or repeatedly using location or network access. Those ongoing tasks can consume power; quitting or restricting the app may help if it is behaving badly or you no longer need the task.
So the app switcher is not a list of programs all draining the battery at full speed. In ordinary use, repeatedly swiping apps away and reopening them can create extra work without stopping much background activity. Letting the operating system handle idle apps—and checking battery settings when one is unusually active—is often the more efficient choice.
