I have been asked to port my original Battery Guide over to the SGS3 threads, so here it is in all it's glory.
Attaining 20+ hours of battery life is not only possible it is totally attainable with most phone configurations. The secret to making this happen is, understanding what are the contributing factors are and knowing what to do first.
This guide will help. After reading this guide, you will be able to understand how to end power eating culprits and answer those same questions we see over and over in the threads...... that is .... solving the passive battery drain and get the 20 hours of battery life we all want and desire.
As we all know, all Samsung Galaxy S 3's and their Chipsets are not created equal. So if something works for one person and not the other, then is it a software, hardware or human error. Chances are it is a combination of all three. Hopefully this can slim those down a bit and answer some questions that you might have or have seen. I have tried to get almost everything I can think of and put it in one place.
You can click on the Post # below and it will take you directly to that post if you wanted to skip some things (although I don't know why you would want to do that)
Post 1: Tips and Tricks
Post 2: Roms/Kernels, OverClocking/Undervolting, Governors & I/O Schedulers
Post 3: Memory Management
Post 4: Apps (for your download pleasure)
Post 5: Proof
I will be using satirical stories and anecdotes to get my point across below. Not meant to offend or point fingers at anyone. I am just using real life references to get to the point. Also I am not much for fancy colors. I tried it at the top here but not so much further down. If there is something specific I want to call attention too, I will BOLD it and maybe RED it too.
This is not a GUIDE to get better battery life but rather a GUIDEline to get it. What is the difference, you say? A Guide is a step by step process that you must/should follow to get the outcome that the person who created it wanted you to get [A+B+C+D should = E]. A Guideline is more of a recommendation that allows some choice or flexibility in the understanding, execution or use [A +B-(C+D) can = E].
TopShelf10 has this to say about getting the most out of your battery life
the problem is, people want to believe that they can save battery without changing their usage habits. this simply is not possible. no rom or kernel will realistically do this for you. if you remove 1 brick from a bag full of 15 bricks, the bag will be lighter, but still very heavy. you need to download "spare parts" or "process monitor" from the market and start analyzing the way your apps are acting. also look into data syncs that are happening in the background. apps that stay open behind your back/what they are doing 9an app called "autostarts" can prevent apps from self-running under certain scenarios). animation speed. polling for notifications. gps. wifi scans. overclocking. cpu/ram usage. proper sleep. widgets. brightness. 2g/3g. data usage. call time. text volume. - THESE are the things that really affect your battery life.
bottom line is, if you truly want to save battery you are going to have to get your hands dirty...there simply isnt a one-click (or one-flash) solution.
1. Be Realistic -
Do you really think that you can get two whole days out of your battery? If you do, then you must have a very important pile of papers it is sitting on to not even pick up your phone for that long. These are phones. These are mini-computers. These are arcade games. And they want, dare I say, need to be played with, talked on or downloaded to. USE YOUR PHONE.
2. Syncing –
I know you are very important and you need to know what LeBron is doing right now, just in case you get a cup for a coffee and he might be in Starbucks at the same time and you get your picture taken with him and upload it to Facebook, Twitter or Google+. That is fine and I applaud you for it and will probably download the picture and Photoshop myself in your place. This is not the problem. Syncing your accounts is. That is what is causing battery drain. Do you really need to have your FB widget (see widgets section) streaming all day long? Does Kim K.’s endorsement of a potato chip really affect your everyday life? I doubt it. Kill them (not LeBron or Kim K. but rather the auto-syncing). Every time you “friend” someone their numbers, contact info gets sync’d to your phone. Also, there are settings in Facebook, Twitter and Google+ that you can upload pictures instantly. Don’t do that. Once you do, it is out in the Ether-World and just swallowed a bunch of battery doing it too.
Settings>Accounts and Sync>Auto-sync>uncheck it
3. Widgets –
They look cool. But widgets are nothing more than RAM and battery hungry monsters that you purposely put in your home screen. Think about it. What does a widget really do? All it really does is monitor an app that you have running. So not only is it running and taking up battery and RAM but the app that it is linked to is running in the background al’ a Facebook, Twitter, Google+, CNBC, MSNBC, BBC,… the list goes on and on because they want us to put THEM on our home page.
What a great marketing campaign the widget is.
“Hey look at me new home screen”
“Cool. Hey what widget is that?”
“Oh, it is X”
“Nice, I’ll have to download that tonight when I get home” and then and there they have you and your battery.
4. Apps –
You have to pay attention to your apps. I repeat. You have to pay attention to your apps. Especially if they run in the background. This can be anything from a harmless .99c game to a monster like Live Wallpaper. The battery drain threat is twofold here because the app is running in the background but it could also be using its anonymous data collection abilities and sending that back to the Mothership. Ever wonder why you have a 4/3G with up and down arrows in your status bar when your phone is just sitting there? This is because some app is transmitting data, whether you are using it or not. There are apps in the market that monitor these situations like Watchdog or kill the data link when the lock screen is enabled like Juice Defender (see Apps below) or you can adjust app permissions like LBE Privacy Guard. Data transfer is #2 on the What Kills My Battery list.
5. Display/ Wifi/ Airplane Mode/ Animations/ Location –
#1 when it comes to what is eating your battery. Always has been and always will be. Accept it and try to do something about it. This part is easy. Just lower the brightness. You can use Auto or set it as a brightness that is low but you are still able to see well enough to function. Live Wallpapers fall into this category. They are cool to look at but static ones take up less RAM and also less display because they are not running all the time in the background. These screens are bright at 100%, so tone it down. (see Apps below).
Another helpful tip is setting your WIFI sleep policy to Always. This can be done by going here Setting>Wireless>WIFI> Menu key>Advanced>WIFI Sleep Policy and set it to Always.
--->Then you can also do this Build.Prop edit as well (this is if you are Rooted, of course)
Allows your wifi to scan less, saving more battery:
wifi.supplicant_scan_interval=240 (I have mine set to 420)
Airplane Mode Toggle:
DocHoliday77 has this very helpful trick regarding Airplane Mode and how it effects your Data/Battery life.
I generally suggest toggling Airplane Mode on/off as a recommended step before running data speed tests, and to help with signal strength.
When you move from one area to another, generally your phone will automatically switch to another tower as the signal/connection to the current tower degrades. This is perfectly fine while travelling since you are not in a single location for very long. The problem comes into play once you have reached your destination. For many people, when they get home from work, for example, their phone will remain connected to the last tower they switched to on their drive home. However, there is very often a tower closer to their home that can provide better signal. The phone does not automatically switch to the better tower because it is still close enough to the current one to have adequate signal. By toggling Airplane Mode on/off, when the radio turns back on it will search for the strongest signal and will now connect to the closer, better tower!
Stronger signal will directly translate to a better battery. The better your signal, the less power is consumed for ALL radio operations (Including Cell Standby, Data, and Voice)! When the signal is weak, the radio requires more power to transmit to the receiver (the tower), which translates to higher battery use.
Toggle Airplane Mode on then off again to force the phone to connect to the best possible tower.
Animations: Set Settings > Display > Animations to .5 animations.
As pointed out by Arlanthir if your device is broadcasting your location, then you may need to rethink whether or not that is good for you and your battery. Generally, your location is based off GPS, Wifi or Mobile Networks. If these are on, then battery drain is occurring. Sometimes you need your location to work with Maps, Google Now, but most of the time, it is because of the unholy trinity, Facebook, Twitter and Google+. I mean, how do you think you "Check-In' at places right?
If you don't utilise these types of features on those three, then go into Settings>Location and untick them. Now there are also other apps like MLB At-Bat and the like that require location for blacked out games or services based on your location. I find that there is always a toast in those applications that notifies me and allows me to turn then on as needed. Then when I am done, I can turn them off.
These are 5 fundamental things that you can do to help reduce battery drain and get some more life out of your phone. Anyone can do these. All you have to do is watch your phone and use some common sense. “Why does my battery drain after only 6 hours? All I was doing was checking Facebook.” Do you really need to be on Facebook for that long of a time? I doubt it. How many services do you have running? How many tasks do you have running? (Android does a good job of shutting down tasks on its own, but if you are using a task killer, it takes more juice to start up an app than to turn it back on, so to say.) Think of it like an airplane. Takes more fuel to get up in the clouds, but once you are up there, it is pretty much coasting along with way less burn.
A special thanks to DocHoliday77 for convincing me to port this over and also for some of his helpful tips as well. You know who he is, so hit his thanks button to show your appreciation for all he does for this community.