[Galaxy S II General] Saber:
How to improve your phone's battery life

It is about time to make a guide to help people who are struggling with battery life. There was a guide to save battery life but that was only for dorimanx users (thanks to voku). This guide is for all s2 users who currently have to battle with their phones lack of battery efficiency. :)

Disclaimer

Here are the things we are going to discuss:

- Battery life myths

- Affects of apps

- Affects of ROMs and Kernels

- Affects of screen usage

- Other things to improve battery life

Battery life myths

Here are some myths that some people believe to cause battery life drainage:

Q. Installing a custom rom will increase my battery life

A. This statement can be true if the right ROM has been chosen. A ROM with less inbuilt apps could have less battery drainage, whereas a ROM with lots a bloatware will be the complete opposite. However, a number of factors can account for battery drain, therefore this isn't necessarily correct.

Q. Rooting my phone will increase my battery life

A. Rooting doesn't save battery life. It just allows the user to modify the phone which would be otherwise be restricted by Google or by the manufacturer. It is installing battery saving apps (like Greenify) that can use root that could save your battery.

Q. Black or dark colours that are displayed on my screen will drain batteries faster than on a white or brighter colour.

A. Dark colours used to drain the battery more significantly than white or lighter colours. But that was for LCD displays! The S2 has a AMOLED display which blacks are displayed by switching off the individual LED crystals, therefore saving battery.

Q. Battery drain can be improved if undervolt my CPU/GPU

A. For most people, undervolting can be a very tedious adjustment a person can make to their phone. The actual battery savings from undervolting is small and can also be a waste of time for the inexperienced. Undervolting introduces instability and lagging if inappropriate voltages have been set and so the user experience will be annoying!

Q. If I reset the fuel guage indicator, the battery life will last longer

A. Resetting the fuel guage indicator (found in custom kernels) doesn't solve battery drain issues. It just helps to relieve the battery drop after rebooting your phone as the fuel guage sometimes needs to recalculate the battery's remaining life.

Q. Updating my ROM to the latest version will give me better battery life

A. In most cases, this statement isn't true. For stock roms, updates can be problematic and lots of things can go wrong during the installation. Updated stock roms can bring more bloatware to the device causing your phone to drain more battery. This happened when android 4.1.2 was released for the s2 and as a result, lots of people were forced to choose to install a custom rom. Custom ROM updates can be a good thing as ROM developers always work on their ROM to fix bugs. This can be a benefit for battery life since more bugs are fixed. However, sometimes an update may not go too well and battery life could start draining quickly after installing the update. Choose the version that you believe is best and/or check reviews/comments on XDA before flashing a ROM.

Affects of apps

You may have heard the less apps you have, the longer your battery life will last. This may be true if you have lots of apps that rely on active notifications, but even with having fewer apps with active notifications, there still could be a noticeable effect on your battery life.

Apps that use active notifications:

Apps that classify as active notifications includes:

- Instant messenging apps like facebook messenger, skype and hangouts

- Any social media related apps including youtube, facebook, google+

- Some games that have social media features

What you can do?

These apps are a likely cause of your battery drain. To prevent further battery drain, these apps can be removed by uninstalling these apps manually. Some phone OSes bundle social media apps with their software bundle, if you don't use social media apps like facebook, uninstall them. If you must rely on using social media apps, try using your phone's browser to load up the mobile version of the social media website. Doing this may save you battery life.

Battery saving apps

Believe it or not, some battery saving apps can drain your battery instead of saving you battery life! Here are some examples of battery saving apps that simply drain your battery:

- Apps that claim to manage your wifi and mobile data

- Apps like Juicedefender that claim to 'intelligently' manage your phones behaviour

- Task killers that don't require root (usually doesn't work properly anyway)

What you can do?

Uninstall the app. Enough said. If you have to use a battery saver, the only one I trust is greenify: https://play.google.com/store/apps/details?id=com.oasisfeng.greenify&hl=en (Note: Requires root)

Google Now

Google now is one of the most commonly used apps on android phones today. It has many features that can make your phone experience easier. However, it is known to have a drain on your battery so here are the things you can do.

What you can do?

Turn off ask google from homescreen or from anywhere on your phone. This speech recognizer function keeps your microphone active which in turn could drain your battery. A better option would be to disable Google now altogether. Some home launchers have an option to disable google now from homescreen, so you will need to disable it from there.

Battery monitors

A battery monitor doesn't classify as a battery saving app. This is because it doesn't do anything to manipulate your phone so it doesn't really save any battery. Moreover, battery monitors look at the statistics of battery drainage which could help users identify their battery issue.

What you can do?

If you experience battery drainage after using and closing an app, install and wakelock detector: https://play.google.com/store/apps/details?id=com.uzumapps.wakelockdetector&hl=en and you can see which app you need to force close to save battery. Apps that have a long awake time period could indicate a possible battery hogging app. Uninstall the app and your battery life could be extended. Another way to check if you have an app that is hogging up your battery is by using the in-built battery settings graph. Pressing the graph will allow you to see a combination of statistics. The statistic you should be focusing on is the awake bar and the screen on bar. If there is more awake than screen on, this usually indicates there is a rogue app. If they are the same, you have no wakelock problems.

Antivirus Software

If you are connected to the internet, there is a chance that you have encountered a virus once in your life. An antivirus may need to be installed to protect your device from viruses, all sorts of malware and even phishing. But what affects do they have on battery life?

So what's the battery affect?

Antivirus software aim to protect your phone without much performance hit. There are some fake antivirus apps that claim to protect your device but instead scams you into buying your product. Antivirus software don't usually use much battery life and are actually quite lightweight (most of them are, but they can still be unsuitable for old android devices like the i9000). Here is a good webpage that discusses the performance and the battery consumption on various antivirus suites for android devices: http://www.av-test.org/en/news/news...tection-apps-put-to-a-6-month-endurance-test/

Bloatware

Bloatware is one of the biggest culprits that just simply steals your battery life. Here are examples of bloatware:

- Any pre-bundled software that come with your phone

- Any apps that you don't even use that came with your phone

What you can do?

Uninstall the apps that you don't need/use. If you can't or have trouble uninstalling certain apps, try using titanium backup to freeze and uninstall any apps you don't need: https://play.google.com/store/apps/details?id=com.keramidas.TitaniumBackup&hl=en (Note: Requires root). Some pre-bundled apps can only be uninstalled from your phone's application manager in the settings.

Affects of Kernels and ROMs

Custom kernels and custom ROMs can have a large variety of benefits for the user. Custom ROMs could add features that are only available on AOSP roms, custom kernels can add hardware improvements and functionality such as support for BLN and more CPU governors. But what are the battery effects concerning with custom kernels and roms?

Kernels

Kernels play an important role in any Operating system. It contains all of the drivers, information and programming required to allow the device to function properly. Without it, our phones will be worthless. Custom roms introduce more features than your standard custom rom kernel and here are the list of some kernels:

- Siyah Kernel

- Dorimanx Kernel

- Gustavo Kernel

- Apolo Kernel

- Speedmod Kernel

- And the list continues

The point is that custom kernels allow the user to customize more things on their phone than normal. This includes CPU governors, IO schedulers, voltages and etc. Here are some things you can do in a custom kernel that will help save you battery

Don't overclock your CPU

As simple as the statement reads, don't overclock your CPU. Overclocking your CPU could boost you phone's processing speed but this can also lead to overheating issues and bad battery life

Underclock your CPU

Here is where the benefits starts to come in play. Underclocking is making your processor run at a lower speed than the manufacturer's specifications. This results in better battery life but could also reduce performance. A slight underclock is enough to improve your battery life by a bit.

Play around with CPU governors and I/O schedulers

Being one of the more experienced XDA members around here, I often see users asking for the best combination of CPU governor and IO schedulers. My response will be to try a balanced CPU governor first or try a battery saving optimized CPU governor, then see which IO scheduler you like most. In my case, I like HYPER and SIO as it is a solid combination and provides great stability and battery life. For more information on CPU governors and I/O schedulers, visit my website here: www.androidmodguide.blogspot.com

Disable LED on touch

LED is a feature that allow your phone's hardware buttons to light up when you touch your phone's screen. This can be a bad thing in regards with battery life. Disabling LED on touch will prevent further battery drain especially if you constantly text others or play games.

Try not using BLN

BLN is a great feature that all phones should have. But keeping the phone's hardware button lights can lead to excessive power drainage. If you find BLN is not too important for your everyday phone usage, disable it. It will save you some battery especially if you get lots of notifications and constantly check your phone for updates.

Enable LCD Power Reduce

Even though the display on our device is an OLED display, the settings still applies for our device. LCD Power Reduce is similar to Adaptive Brightness in a way as they both alter the display settings when displaying different content. This feature is included is most custom kernels and is usually set to enable by default. If you disable this because you don't like the colours, you are missing out on extra power savings.

ROMs

One of the great things of rooting your phone is that you are able to flash a custom ROM. Stock roms can come with lots of bloatware and unnecessary apps that it just simply slows the phone down. Custom ROMs can help speed up your phone as they generally come with less or no bloatware and are better optimized for our device thanks to the developers of the ROM. Here are some examples of Custom ROMs:

- Cyanogenmod

- Paranoid Android

- Omni ROM

- Slimkat

- And many more ROMs :)

Here are the thing you can do in a custom rom that can help you reduce power usage

Avoid android lollipop

Android lollipop was one of the most anticipated android releases in Google's history. Lollipop comes with heaps of new features, optimizations and fixes that just make android better for everyday usage. However, with more features comes more chance for apps to drain your battery. Not all apps run on lollipop without bugs and are susceptible to stability issues due to the newly implemented ART runtime. If you care about your battery life, stick with stock android 4.1.2 or custom kitkat rom as they don't suffer from the same issue!

Use ART

Not the paintings or the drawings that you would think of when you see 'ART'. ART (or Android Runtime) is a new runtime for android that is supposed to replace the aging dalvik runtime that currently run on most devices with kitkat and below. The benefits of using ART is that it supports 64bit chips (which doesn't give us any benefits), faster app load times and slightly better battery life. ART for kitkat is still a bit unstable and it requires more of your storage space when installing apps (less apps, more space used). However, not all apps are compatible with ART so make sure to google the app and version (important!) before switching to ART.

Enable battery saving GPS settings

Enabling GPS on a phone can seriously drain the battery quickly if someone was to forget that it was left on. Newer android versions allow the user to use different combinations or methods to determine the person's location which can potentially save battery life for people who use location services a lot.

Enable Adaptive backlighting

A relatively new (yet still old) feature on newer android versions include a feature that controls the brightness of your phone when specific content is shown. The difference in brightness in not really noticeable and so it is a feature that everyone should enable.

Use the default messaging app for your messaging (SMS)

With Android Kitkat, you are able to set the default messaging app. The default messaging app that comes with your phone is most likely a basic messaging app that allows you to send any kind of normal SMS to someone else with a number. Third party messaging apps like hangouts are more heavy with features and this can be a bad thing if you care about your battery. The simpler the messaging app, the better! (Not regarding the look, but I'm talking about features)

Use lighter home launchers

Home launchers determine how your phone would look if you were to access your apps that are on your phone. Launchers can be designed for visual and function purposes. The general rule with launchers is choose a lightweight launcher (like nova launcher) for your phone and your phone will have more ram and responsiveness. Battery life could be slightly improved by switching launchers too.

Use stock android browser

Web browsers on android are a must for most internet enabled phones today. With the large variation of web browsers, people may feel tempted to try out a different, more advanced browser. However, the truth is that if you browser on the web a lot, third party browsers can drain your battery faster than stock browsers. Stock browsers are the browsers the come with the OS. It may not be the most aesthetically pleasing interface but it usually lighter than most their party browsers on the play store and can save your battery!

Use stock keyboards

Without a software keyboard on our device, how else could we type a message or search for anything on the web (excluding voice and hardware features)? The keyboard bundled with stock roms may not be the easiest to use so you might download and use a different keyboard. Third party keyboard could be resource hungry and as of a result, it could drain your battery. Choose a simpler keyboard like android keyboard (bundled with AOSP roms) or google keyboard with holo design.

Avoid using audio improvement apps

You may have seen an equalizer app or an app that specifically is made for users to tweak the sound of the music. This can be great when you want to improve your audio but this could cause addition audio drain to your phone. If you can, try not tweaking the settings too much or make any changes that would improve the loudness of your speakers or earphones as this requires addition power. Audio enhancing apps generally require more processing power from your CPU and from your DAC, so that means less juice for your phone! If you are using an app like viper4android, use the battery saving mode when installing the driver and don't install the super high quality mode to save battery!

Affects of screen usage

Most people are unaware that one of the biggest factors that affects your battery life is the screen usage. You screen is one of the most power hungry components on your phone and so it's best to limit the brightness to get the best possible usage time. Here are some things you can do to stop screen battery drainage

Decrease time to turn off screen automatically

Having the automatically turn off screen feature set to long periods of time can seriously affect your battery life, especially if you forget to lock your phone after you are finished using your phone. Setting this to a shorter time will ensure no extra battery life is wasted from excessive screen on times.

Decrease your brightness and turn off automatic brightness

This is one of the most common actions to do to increase your battery life. Having your screen too bright can lead to serious battery drain. Find a setting that suits you and disable automatic brightness as it could adjust your brightness even once setting your brightness level.

Use darker, black wallpapers

This isn't necessarily a good method to save battery but the evidence suggest that actual black colours will save you battery life. Choose a wallpaper that uses black colours and your battery life should be slightly better (if you find yourself using your phone to only use the homescreen :p)

Other things you can do

If you have tried everything to fix your battery life and you don't see any improvement, you can either buy a new battery or simply buy a new phone.

Use greenify

You may say "I thought battery saving apps were bad for battery life?" Well in this case, Greenify is different from most battery saving apps as it is responsible of 'hibernating' your apps stocking them from leaving your phone on wakelock which could consequentially result in loss of battery life. This option is available for all other rooted phones too with different versions of android too.

Buying a new battery

If you have done everything possible to fix your battery life and your battery life can't stop depleting, it is probably a good time to buy a new battery. There are a number of ways to check if your battery is dying buy monitoring your battery voltage depletion or seeing a drop in battery life when your phone is hardly awake. When buying a new battery, be sure to buy from a trusted source and if possible, buy a genuine battery. There are a lot of compatible batteries that state that they have {so and so} battery capacity but the chances are they have the same capacity as the genuine battery (and sometimes less!).

Disable fast dormancy

Fast dormancy(FD) is a feature that controls your mobile radio by putting it to sleep when not in use. This can be a good thing if your carrier supports this but it could be a bad thing if your carrier doesn't With stock rom, you can easily disable fast dormancy by going on the phone dialer and typing *#9900# . In custom roms, you can use quick dialer numbers, so you will have to use an app called fastdormancy toggle by the legend gokhanmoral: https://play.google.com/store/apps/details?id=com.gokhanmoral.fastdormancytoggle.i9300&hl=en. Even though the description says it's for the i9300, it should work with the i9100. As you can see on the image above, this shows the different combinations of phones that have FD enabled or disabled and carriers that do and don't support FD.

Mediascanner bug/Music bug/FP bug/Fuse bug fix

Known as the infamous music bug, this bug has existed since Android 4.0.3. The problem was caused by the corruption of FP registors, in other words, when your screen turned off, the code for saving your state of your phone was not properly coded by Samsung, and as of a result, battery life was lost. The music bug affected all users of android 4.0.3 or later and could be noticed when after playing music from an external sd card where the music would just suddenly stopped. To fix this bug, install a custom kernel that includes this music bug fix (like apolo kernel, dorimanx kernel or gustavo kernel) and your problem should be fixed. Note: This also requires a rooted phone with custom recovery.

Change your phone's modem

A modem modulates and demodulates signals for communication between networks. Your phone's modem is responsible of providing a software layer that controls the mobile cell to communicate with the cell tower. Sometimes, the current modem may be poorly optimized for your carrier/device which may lead in some battery drainage. To solve this issue, you may have to replace your current modem software with a newer or different one. The benefits can only be determined by the user, so it is hard to tell which modem is best for your usage. Have a look at this thread to download a modem: http://xdaforums.com/galaxy-s2/general/ref-samsung-modem-ril-cwm-installers-t1881304

Factory reset

Some battery drain issues that can't be solved using apps like greenify or issues to do with mediaserver can be resolved with the good old factory reset. Factory resetting your device will return your device back to the factory defaults (deletes your apps, settings, etc) but doesn't delete you personal files (like music, photos, etc). Be sure to backup all important files just in case something doesn't go as planned. Beware: Stock Android 4.0.x Touchwiz users are advised that factory resetting with stock recovery with stock kernel can cause your phone to hardbrick. Once your phone is hardbricked, your phone is officially dead unless you buy a new motherboard for your phone! Update to JB 4.1.2 first then factory reset or install a custom kernel. To check if your phone is affected (if you have insane chip), download and run this app: https://play.google.com/store/apps/details?id=net.vinagre.android.emmc_check&hl=en.

Keep your phone cool and don't play games while charging

This is more of a maintenance tip for your battery but when you charge your phone, your phone's battery and circuitry can heat up. This heat can damage your phone's battery so it is important to keep your phone cool. Remove any cases on your phone and allow it to cool naturally. Don't play games while charging your phone as this will heat up your phone even more until your phone gets very hot. Remember that in the battery world, cool is better.

Huge thanks for all of the kernel developers including [MENTION=2376110]dorimanx[/MENTION], [MENTION=1670821]cybernetus[/MENTION], [MENTION=4663860]Computoncio[/MENTION], [MENTION=3445281]pedestre[/MENTION], [MENTION=4217277]Gustavo_s[/MENTION], the developers of the custom roms including [MENTION=4193338]CyanogenMod[/MENTION], [MENTION=1228651]fusionjack[/MENTION] and everyone else who made customizing the s2 possible.