I would like to know how the Android OS manages memory for Applications. When are the various memory hardware components like ROM, RAM, Internal storage and External storage used during an Application's life-cycle ? Does all this have an effect on battery utilization ? For e.g. If the RAM is half free then will it consume only 50% of power and likewise for ROM , Internal storage and external storage.

In short I want to understand and decide how I should use my Android phone to minimize battery consumption.

  • 1
    If you are looking for battery consumption, I don't think the storage / memory has a lot to do about it. Things like 3G/4G, WiFi, Display, Voice Calls are the things I would focus on to save battery. Nov 22, 2012 at 9:31
  • We have a lot of questions here on how to manage battery life, you can find them with a search :). I don't think the ins and outs of how Android works on such a low level are really on topic here, they are more concerns for OS developers than anyone else. Nov 22, 2012 at 20:10

3 Answers 3


Your question would require a rather lengthy answer, and does not really fit the scope of our site. So for a complete answer, you'd better find yourself a book.

Some short hints, though:

  • Thanks for the input. I will wait for other answers for a week and then vote yours as the best.
    – Barun
    Nov 22, 2012 at 11:25
  • Thanks! Glad it helped :) Sometimes it's hard to spot the information when one doesn't exactly know what to look for...
    – Izzy
    Nov 22, 2012 at 12:01

If the RAM is half free then will it consume only 50% of power

Nope. RAM uses power no matter whether the cells are used or not.

The biggest consumer of power in a phone is the display (screen), the various radios (Wifi, 3G/4G, GPS, bluetooth, etc), and the CPU and GPU.

ROM is an overloaded term, it is technically an abbreviation of read-only memory, but there is actually no such thing in modern smartphones. The "read-only memory" (ROM) in modern smart phone is actually writable. What most people say when they say ROM depends on the context, sometimes they meant the flash storage (hardware) and sometimes they meant the firmware (software).

In most Android devices, internal and external storage both uses flash storage, so it's should not be surprising that their power requirements are similar. However, unless you're using an application that is constantly reading or writing large amount of data, the power draw from flash storage are generally quite minimal to overall power usage.

Does all this have an effect on battery utilization?

Yes, but on typical use cases, they are not the major power draw. In typical usage patterns, the display and the antennas trumps all other components by miles.


Battery consumption depends on your screen active time, 2G/3G/4G/Wi-Fi data connectivity, bluetooth, voice calls etc. It has nothing to do with how much of your internal or external storage is free.

And from whatever I have seen, if you use task manager to kill the apps or force stop them usually drains more battery because those apps try to start back. As far as I know it has absolutely nothing to do with your ROM, I mean Hardware ROM. When it's firmware which is there on ROM it can affect the battery consumption if it's not optimized properly ( kernel tweaks etc)

it's better to keep auto sync off to save battery. Or run it after every 10-15 minutes.. it's upto you!

  • Auto-Sync has nothing to do with task killers -- so that part is no conclusion from the former. True is however keeping it off saves battery -- but so does switching to Airplane mode. It's rather a question of what to auto-sync and how frequently, to match the users requirements with his/her wish for battery runtime ;)
    – Izzy
    Nov 22, 2012 at 10:30
  • I think the ROM he meant wasn't the ROM that you install, but the hardware itself. Btw, depending on the ROM you run, it may affect on battery consumption
    – Markissimo
    Nov 22, 2012 at 10:30

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