A 2020 Samsung Galaxy A21s can remain functional as a secondary device by implementing effective battery management and power-saving strategies, according to expert advice.
An ageing Samsung Galaxy phone can still be useful if the battery is managed carefully. The example in How-To Geek centres on a Galaxy A21s from 2020 that is now used as a secondary handset, where modest demand and a few battery-saving changes have made a practical difference. Samsung’s own support material says battery life is shaped by both usage and device condition, so the first step is to separate a worn cell from software-driven drain.
Samsung recommends checking battery status through the Samsung Members app. In its diagnostics section, users can run a battery test and see whether the result is classed as “Normal”, “Weak” or “Bad”. That matters because a healthy battery can often be improved with settings changes, while a failing one is unlikely to respond to much tweaking. Samsung also says the same app can be used to run broader device checks, which helps confirm whether battery issues are part of a wider performance problem.
Once the battery itself is ruled out, the next task is to identify what is using power in the background. On the A21s, the biggest drains were not obvious personal apps but services such as Google Play Services, the Galaxy Store and Google Play Store, all of which can wake frequently to sync, update and maintain the phone. Samsung’s battery optimisation guidance says this is exactly the kind of behaviour worth reviewing in the Battery and device care menu, where users can inspect app consumption and adjust power use more deliberately.
Power saving mode is the most immediate tool for extending runtime. Samsung says it reduces background activity and can also lower display brightness and CPU speed, depending on the settings chosen. That makes it well suited to a spare handset used mainly for calls, occasional photos or light app use. However, it is less suitable for demanding tasks, because it can slow the camera and make the device feel less responsive.
The other gains come from cutting radio use when it is not needed. Even without a SIM card, a phone may still search for a mobile signal, so Airplane mode can prevent unnecessary scanning; Wi-Fi can then be switched back on separately. Bluetooth, Location and Nearby device scanning can also be disabled when they are not required. Combined with an 80% charging limit and reduced background syncing, these changes can turn an old Galaxy into a far more dependable backup device.
Disclaimer: This content is intended for informational purposes only. Readers are advised to exercise their own judgement, conduct due diligence, or consult a qualified expert before acting on any information provided.
