Android ROM, RAM, Internal storage, External storage and Battery utilization

Question

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.

Answer 1

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:

• No such thing as "free RAM", Linux (Android is based on that) makes good use of it. If not required by apps, it will be used to cache e.g. the file system. This not only gives faster access (as RAM is faster), but also saves battery (as physical file system access is minimized). See also:
  • Are there guidelines on how much free RAM a phone should have
  • How do RAM and processor speed affect overall performance on Android?
  • Unix & Linux: real memory usage
• To understand the life cycle of an app, you might refer to the Process LifeCycle description on the developers site
  
  ^{(image taken from BottomLessInc Blog)}
• to minimize your battery consumption (or maximize its runtime), there are a lot of useful answers on our site already. Some examples include:
  • What is Cell standby and how can I keep it from eating my battery?
  • What can I do to increase battery life on my Android device?
  • Which consumes less battery: Wi-Fi or 2G data?
  • Minimized Apps: Do they consume more battery?
  • Many more can be found browsing the tags battery-life and battery-usage

Answer 2

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.

Answer 3

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!