Using RAM management apps in Android which clear the RAM of all applications is, in fact, detrimental to the system and may degrade the performance and battery life instead of conserving battery power.
If an app is stored in the RAM, it consumes battery power.
The truth is- When an app is stored in RAM, the bits in the RAM are held as 1s or 0s accordingly, and the memory is cleared whenever the app is removed. Holding a bit as 0 or 1 takes the same power. There is no effect on the power usage if a bit is held as 1 instead of 0, as this involves only data storage and the kind of bit being stored in that memory location does not matter.
It is the CPU usage that affects the battery life, and not the RAM usage. If an app is present in memory and is consuming a lot of battery power, it indicates a high usage of the processor by the app, possibly as a result of weak code management by the developer of the app. Killing or uninstalling such an app may help to increase battery life, but the cause for this is not RAM usage, rather it is the excessive usage of the CPU.
Storing an app in memory helps in:-
a. Improving the app startup time, which also helps to conserve battery life, instead of loading the app into memory once more.
b. Reducing the number of context switches taking place and lowering the number of swap-in and swap-out phases from the RAM memory.
RAM cleaners remove these benefits by:-
a. Clearing all apps from the RAM, so the startup time increases. The performance of the system degrades.
b. More number of swap-ins into memory consumes more battery power instead of performing the function that RAM cleaners claim to perform.
Android keeps an application in the memory as long as possible. An app is removed from the memory only when there is shortage of memory for a new app to be loaded – at which point a chosen app is killed, and the new app brought into memory. The app which will be killed is chosen based on its priority and current status in the system (see Priority Management) and the lowest priority apps are killed first. The Android memory management system (including the garbage collector and the memory allocation-deallocation mechanism) is robust enough to handle memory efficiently, and a memory management app to clean the RAM regularly is not required, and can even be detrimental to performance and battery life.
Using a RAM management app may help in only one way- no swap-out is required when a new app is loaded. But it has far more negative effects and must not be used. Doing so negatively affects battery life, contrary to popular belief.