Inside Android, how to extend your battery life

Howdy!  It's me again, and this week we're gonna talk about something near and dear to all of us -- battery life.  It's always at the tip of everyone's tongue (especially as new phones are released), and all the information out there is enough to make a person lose his or her mind.  Hopefully together we can work through it all, separate the fact from the fiction, and figure out how to keep everything out of the red.

Prepare your beverages, smoke 'em if you got 'em, and follow the jump so we can figure this out together.

Where we all need to start is with the realization that Android devices aren't phones. They're tiny little laptops with voice capability.  Those of us coming from feature phones (I hate the word dumb phone, you won't see it here again) or BlackBerries are probably shocked at the amount of juice these phones tiny laptops can suck up in a short amount of time.  On the other hand, folks from the WinMo, Pre or iPhone camp already knew battery life is, and always will be an issue with devices that are so feature-rich.

Another thing to remember is that if you've just got your new Android phone, you probably haven't given it much of a chance to sit still unless you're asleep :)  Once you're done setting it all up and checking out all the coolness that oozes out of it, battery life will get a little better.

Charging it up

Charging the HTC Hero

Straight and to the point -- you'll have to charge your Android phone at least once every day.  Get into the habit of hooking it to the charger at night before you go to sleep.  I wish I could tell you of some magical trick that gets you two or more days out of a battery without killing off everything that makes the phone worth having, but I can't.  If you're the type who never puts your phone down, you might even need to charge more than once a day.  Unless you want a much bigger device to hold a much bigger battery you're going to have to deal with
charging more often that you would like.  On the average though, using the tips you find here and elsewhere across the internet you'll probably manage to find a way to get through a full day on a single charge.  Of course a spare battery and charger or an extended battery is always a wise investment.

Conditioning the battery

You'll see that in a lot of various help forums and Android fan sites people talk about conditioning a new battery.  Not needed.  I won't bore everyone with the technical mumbo jumbo about battery types and manufacturer recommendations, you can find those HERE(Isn't it sad that I even have pages like that bookmarked? I need more hobbies!)  In plain English you do not need to cycle the battery in your new phone.  Charge it when you're done using it, try not to let it get too low too often, and try not to leave it on the charger more often than necessary.  Yes, there are complicated overcharge protection schemes in the battery charging circuit, but the battery itself will last longer if it doesn't sit with a full charge too often.  My advice stands -- charge it every night, take it off the charger every morning, and if you know you'll have a bit of "phone down time" it doesn't hurt to partially charge it throughout the day.  The battery is only designed to last about a year anyway, so rather than try to squeeze two more weeks of life from it just enjoy the year by using it.

After all that, there is a reason to condition your phone itself via the battery and charger.  A lithium ion battery (the kind in modern cell phones) has a memory.  Android reads this memory and translates it into human readable information -- the battery meter.  Every once in a while, it's fine to let the phone run down the whole way and then recharge. This helps keep the battery meter and the battery's actual memory on the same page and give a more accurate reading for battery life. If you're the geeky type and have rooted your phone, you can delete /data/system/batterystats.bin and reboot to do the same thing. (There should be an option for this in your Recovery module, if you're not running stock.)

Tips to save battery life

Charge battery Android

There are some things you can do to improve your battery life.  Most of these are common sense, and the folks in the forums have done a fine job covering some of them, but let's list them here in a nice and easy to read consolidated post.

Screen brightness

The screen on your phone is going to use the most battery.  It's  a big power hungry beast.  Always use auto-brightness if you can.  If your model doesn't have an auto brightness setting, pick something sensible for a default and work your way up.  I suggest starting at 30 percent and see if it suits you. 

Also remember to set your screen timeout -- as in the amount of time of inactivity before your screen goes dark.  Having the timeout set longer than 1 minute is just asking for trouble.  On the other hand, the inconvenience of having it set to 15 seconds isn't worth the hassle of unlocking the phone every time you touch it.  Thirty seconds or 1 minute is pretty sensible and should be a good starting point.

Android powercontrol widget

If you have a phone with an LED screen, you'll find auto brightness doesn't work well outside.  Hopefully this is something that science can figure out, but for now we can use the power control widget (sorry guys and gals stuck on Android 1.5, I feel for ya).  The screen brightness button has three settings -- think of them as low, medium and high.  The "high" setting cranks the screen to the max for use outside, the medium is a nice setting for indoor use, and the low works well in the dark listening to podcasts in your undies under the blankets.

Desktop background

Yes, those live wallpapers are cool as heck.  They also use some battery.  Not a lot considering what they do and their special effects, but enough to warrant discussion.  Anytime your screen is on, the live wallpapers are running.  Displaying them on the screen uses precious juice.  The live wallpaperss also use the processor, which also uses up the juice.  Again -- these aren't the battery hogs a lot of folks make them out to be, but every little bit counts.

An interesting note - if your phone uses an LED screen, dark wallpapers use less battery to display than light.  Not enough for me to worry about the color of my background, but I'm tossing it out there for the folks who want to squeeze every last drop. So here ya go, have a cool one on me :)

Wallpaper for Android

click me for the full res version!

GPS

When GPS is on, it uses the juice.  HARD. I don't mean when the setting is on, I mean when it's actually being used.  There are two ways to deal with this.  The simplest is to just shut GPS off unless you need it.  (Power control widget FTW!) The other way is to keep an eye on your status bar.  When GPS is running, you'll see the icon that looks like Jerry lost his mind and is using his satellite dish to communicate with the aliens. Not really, that was only once and I'm sure someone slipped something into my drink.  This icon is what we're talking about:

Android Maps GPS

If you see it, your phone is searching for GPS satellites and will draw power like nobody's business.  Sometimes we want or need this.  Looking at Maps, or checking into your favorite club with Foursquare, these kind of things. Any other times we don't want it running. If you see it's stuck on, or is starting and stopping when you think it shouldn't be, that's something you need to investigate.  We'll talk more about how to investigate a bit later.

WiFi, 3G, and how it affects things

The second biggest battery killer (after the screen), and the one most apt to cause battery life problems is the 3G radio in your phone.  Looking at the sky and determining which signal to lock on to, and when to switch, is a huge drain on your battery.  You can test this yourself.  Spend a day outside doing some drinking doing some healthy activities and check your battery life.  The next day, spend it inside your cube at work, or deep in your basement where the signal sucks.  Your battery life suffers.  A lot. 

Believe it or not, the WiFi radio uses a lot less battery.  A big part of this is the way it locks on to a signal and doesn't switch until it's told to, or the signal degrades enough that a proper connection can't be maintained. We can use this to our advantage, because that's what we do -- exploit everything we learned from the Science Channel to our own benefit :)

If you find you're having 3G signal issues in a place you spend a good portion of your time, invest in a cheap wireless G router.

Wireless G?  Are you crazy?  I want N!

If you have one already for other things like a computer or the toaster from Star Trek, N is good.  It's seven letters more than G for goodness sake :)  Just make sure to fiddle with mixed mode so your phone can connect and call it done.  But if you DON'T already have a WiFi router, a $50 router from WalMart will provide a connection faster than your phone can use.  Even if you have wireless N on your phone, it can't process the information as fast as the router can toss it out.  Save the coin, spend it in the Market.

Once you're connected to WiFi, have a look at some settings.  The first one we want to look at is WiFi sleep policy.  To get there, open the settings on your phone and hit Wireless and networks, Wi-Fi settings, and hit the menu button. Press Advanced, and have a look at the pictures below

WiFi Settings Android WiFi sleep policy Android

Pick Wi-Fi sleep policy, and set it to Never.  Yep, this sounds like it would use MORE battery, but it won't.  When WiFi is on, 3G is off.  When your screen is off, and WiFi is set to shut down, 3G has to kick in to get notifications, check mail, etc.  Leaving WiFi on while the screen is off keeps the power hungry 3G radio off and forces it to behave.

Another thing to consider is disabling the "Always on" setting under mobile networks if you have a CDMA device.  You'll find it under settings, Wireless and networks, Mobile Networks.  Enable Always on is set by default.  You can shut this down.  Look at the pics for a second

Android always on mobile Android mobile warning

See that warning in the second pic?  That means you're not going to get much use out of third-party apps that need to stay connected, and even some built in Android apps don't play very nice.  This is because we told the phone to shut off the data connection.  You'll still get phone calls and text messages, but the rest will be hit or miss. In my opinion this is only useful when you have a bad 3G data connection and no WiFi to mooch off of.

If you're using a GSM phone, you might have a battery-saver, too.  Under settings, Wireless and networks, Mobile Networks as well.  You can shut the 3G radio off and force the phone to use 2G connections only.  Look at the pic below to see what I'm talking about.

Android 2G setting

These tricks won't help if your voice signal is weak.  Those bars in your status bar are a measure of voice signal strength.  I you see them stay very low most of the time, or always seem to jump back and forth, you'll need to look at your actual signal strength.  You can do this under settings, About phone, Status, Signal strength.  Look at mine below:

Android signal strength

If yours looks like this (a number lower than -95...negative numbers, -100 is lower than -95) then you have issues.  My issue is living out in the sticks and trying to get a T-Mobile signal :)  One more tower T-Mo, please...just one more tower.  If your phone signal strength stays like this ALL the time, head back to your carrier and let them have a look.  If it's just in certain areas, look into a femtocell.  Your carrier can provide one, and are usually pretty helpful about getting you one with minimal costs.  They want to keep your business, so good signal where you live or work is important to them too.

Task killers

Ugh.  These two words will haunt me 'till I die I think. Read this. Don't worry, we won't go on with out you.

Back already?  Good.  Now you have a better understand of task killers, and why when and how to use or not use them.  If you decide to use one, make it helpful here, too.  Anytime you run an app that uses your camera, open the task killer and make sure it's closed when your done using it.  This could be placebo effect, but I've found a big difference by killing off things like barcode scanners and Obama Camera when I'm done using them.  YMMV.  But hey, if you wanna roll with the task killer, what's it hurt?  In my opinion, you're better off not using one if your only need is to try to save battery.

Android task killer

Troubleshooting

So you think you have a problem, where the heck do you look to find it?  First we're gonna talk to the good people still suffering with Cupcake.  If you're running something lower Android 1.5, update your phone for goodness sakes.

Spare Parts

Android spare parts

Market Link | AppBrain
spare parts QR code

Download it from the market.  Open it up, and press Battery History.  Look at the pics below:

spare parts spare parts battery stats

Look through these settings and see what's been using the most battery resources.  If it looks like something that shouldn't be using so much of it, fire off a question in the forums.  We've set up a special thread in the forums to use just for these kinds of questions, where we can get a bit more in depth than we could in the comments.  We still love to hear your comments of course, so feel free to say hey down below even if you had a problem to post in the thread.

Now if you're running eclair, there's a different way to check all this out.  Menu, settings, About phone, Battery use. 

Nexus one battery stats

Notice 14 + hours since off the charger, and 73 percent battery left.  You can do this, too.

Again, have a look, and if anything seems out of the ordinary, throw it out to the forums, and we'll all dig together.  And if you're lucky enough to have had issues and solved them, feel free to hang out there and jump right in :)

It's impossible for you to get the same battery life you expect from an old Blackberry Curve or that even older (and just slightly less feature rich *zing, I kid, I kid -- don't knee me, Kevin!*) Moto c139, so don't even think about it. But hopefully some of these ideas can help you stay running a little longer before you're scrambling for a micro USB cable.  In any case, none of it will hurt :)

Next week y'all,
Jerry 

 

Reader comments

Keep your charge on -- how to improve battery life on your Android phone

61 Comments

Thank you for this article! I knew about using wifi when at home (with poor signal), but I didn't know about using the "Never Sleep" option for it. Hopefully that improves things! I'm also going to look into the femtocell idea... that seems like a great way to boost my signal.

Because I'm not about to mention altering kernel source and running your phone at unapproved specs on the front page of Android Central ;)

I had a section on custom kernels for both the msm7xxx and snapdragon (only phone processors I have experience with), but in the end decided against it. I have good luck with it, you may too, but it's still outside specs and not recommended by the manufacturers.

lol. I thought about that, too. And then I looked at the image we run at the top of the column. :) The point is that if you even know what an undervolted kernel can do, and how to add one, then you're already ahead of the game. (FWIW: I'm running Kmobs' 925mV kernel on the N1.)

When you have wifi set to never sleep it jumps to 30% or higher on the battery usage meter so it definitely drains the battery faster than having it connect whenever you wake it up from sleep...maybe 3G just doesn't show on the battery meter but I can't see how 3G would use more power than wifi.

Because the 3G radio chip has higher power requirements, and it's constantly polling to stay locked on the best signal available.

WiFi connects to the signal you tell it to, and stays connected until it drops or you tell it to disco. A dedicated IP system is always going to be more power efficient than a "revolving" style IP system. This is why WiMax was invented, dedicated IP connectivity for things like traffic cameras, parking meters, or other stationary equipment can run always connected using very small storage batteries with solar trickle chargers.

Its the black bar with 5 settings on it. Its only available for 1.6+ phones. If you have a Hero/Eris, you can use the settings widgets from HTC, but they don't provide one for screen brightness. You have to manually go settings and change the screen brightness (or use the autobrightness on Hero/Eris).

Android 1.6 and up, has a widget with 5 buttons (as seen on Jerrys 3rd picture top to bottom) that lets you turn on or off different services like GPS or Wifi and lets you adjust the brightness.

MMS doesn't work on my sprint hero when I am connected to WiFi. MMS messages both sending and receiving fail. Therefore I choose to keep WiFi turned off because my phone is too stupid to realize it needs to switch on its own.

LOL. I hear ya. Sprint's gonna get right on that and fix it in April, no wait May, well maybe June,....Someday.

It's not just you. I use Bar Control from the market to keep a quick shortcut to wifi in my status bar, and pop wifi on and off when I need to send or download a MMS message.

does having wifi on, with no networks connected, drain the battery more? for example, i use wifi at home, but if i leave it on while at the gym (no wifi available) will it continue to search for a wifi signal and drain the battery?

It drains a little more scanning for new wifi connections. If you're not connected to WiFi, best advice is to turn it off. No need to use battery searching for connections AND staying connected to 3G.

There's an app for that (lol)
WiFi Status by Andrew Schwimmer in the market is free, and alerts you when wifi is on and not connected.

Cyanogen :) It's built into his latest ROM, and is also in his source tree if you want to build your own ROM.

The missing status bar clock is courtesy of britoso @XDA

Ok thanks. I was hoping I could get it without rooting! Still nervous about it. But I think it's a matter of time before I give in.

Thanks for the informative article & awesome wallpaper. I think it'd be awesome if you guys did an article on where to find great-looking wallpapers. I'm always looking, and always failing. I know it's not really an issue of functions, but let's be honest, having a pretty-looking phone is damn important! Especially so that we can rub our wallpaper goodness in the faces of those iPhone users who can't do it yet. :)

Expect the same results with the EVO as you would get from the Incredible or Nexus 1.

Of course any tips that focus on EVO specific features will make there way here as well :)

You know... i did the worst possible switch (from a battery life POV, not that I regret the switch). Had nokia E52 and went for Moto Milestone. From 10-12 days battery to 1 day. IT STILL HURTS after more than 1 month!! :D
That being said, I can't help but wonder how the E52 manages to get that kind of battery life. I mean... it has a much smaller screen, but other than that it's a 600MHz CPU, it has multi-tasking, wi-fi, 3G, GPS and every other acronyms you might think of. It just seems strange that ~30% smaller screen can mean 1200% battery life.

One thing we didn't mention -- and this goes for everyone, but especially you Incredible owners -- is that you're just NOT going to get the same usage out of a 1300mAh battery. These tips will definitely help, but there's a finite amount of juice available. Third-party extended (stock size) batteries FTW.

Any hard data on GPS battery usage?

Its a receiver, not a transmitter, and thus should not draw a dramatic amount of power. Even the calculation necessary to fix your current position are largely done inside the GPS chipset.

But even a more basic question is since the GPS is built into the Snapdragon (on my Nexus One), ( http://www.qctconnect.com/products/snapdragon.html ) how could you possibly differentiate GPS battery usage from battery usage associated with these tasks (mapping, searching, etc) when those tasks typically are high battery consumers.

Running a simple GPS app without mapping does not seem to draw much power, as long as you don't prevent screen sleep.

Simple. Turn on location tagging in the camera app. Open camera app, and use a Linux script to poll battery stats every x milliseconds via ADB. After a sufficient amount of time, turn of location services and retest. Compare data.
Battery stats are just a dynamic file. It's easy to determine battery use for sensors, services or applications by reading its contents while those sensors, services or applications are running. Battery Graph in the Market does this for you as well.

I think it would have been good to mention that some apps will kill your battery. I love streaming audio or listening to podcasts on my phone but they will kill your battery faster than a bright screen or wifi.

You're right. Sometimes I forget the simplest things because I focus too hard :)

I hope most people would know this, but I should have touched on the subject a bit.

Thanks so much for this great article. As a new Incredible owner and noob to Android these tips are like gold...and for that matter, so were a lot of the comments. How did I go for so long on a blackberry???

Let me see if I understand this. A LCD screen's backlight is always on when you're using it, and it's the LCD's polarized pixels that activate to block the light. As the light is blocked, depending on what pixels activate, you get colors, or black. So IMHO, I believe the lightest backgrounds use the least amount of energy because the pixels don't have to be activated to block the always-on backlight.

I think things like Plasma displays and OLED/AMOLED screens like the Nexus are the ones that a dark wallpaper would mean less energy used, right?

Yep. LED tech uses less energy to display dark colors because they don't have to light as many LEDs. Another cool tidbit - using green colors will make the display last longer, again in tiny amounts though.

Your theory about LCD makes sense as well. I've never heard it and haven't worked with LCD enough to know it. Thanks for sharing it!

Both you and the author of this article are wrong.

There is an important difference between LCD, LED, and OLED/AMOLED screen technologies and people aren't properly distinguishing between them.

To start, most screens on phones these days are LCD screens. LCD screens require the use of a backlight and an LCD panel that blocks/modifies the light to achieve colors. LED only describes the type of backlighting (which is incidentally only useful for monitors and TVs, as these displays have typically used CCFL tubes for the backlighting and have just started to make the transition to the more energy efficient LED backlighting). I believe that cell phones screens have *always* used LED backlighting given the obvious size constraints.

Because LCDs rely on a constant backlight, there is no (or negligible) power savings regardless of the color of the screen. When you see a black screen, the backlight is still on and as strong as ever, the LCD is merely blocking any light from coming through. In a nutshell, LCD/LED they are all the same thing and are not affected by wallpaper or screen color.

Now on a handful of new phones, the Nexus One, Incredible, etc., that are using organic LED (OLED) screens (AMOLED is a variation of OLED). The magic of OLED is that each pixel is photoemissive and actually generates its own light. Thus, there is no need for a backlight (and this is why OLED are known for having such amazing constrast and blacklevels -- the pixel can essentially "turn off" its light source and go full black, whereas in an LCD, because the backlight is always on, you are limited by how "black" you can go). Because of this, in OLED/AMOLED screens, if you have a dark or black background, you can save energy.

This is why on the Nexus One a lot of the programs like gmail have had their color schemes changed to be more dark/black friendly.

edit: added a useful link:
http://blogs.wsj.com/numbersguy/does-a-darkened-google-really-save-elect...

Thanks! The documents I got and folks I talk to from Samsung (admittedly, meant for consumer info and not very technical) did not differentiate between LED and OLED, so I assumed (yes, I know all about assuming :) ) that they meant screen LED technology on the whole.

My strong point is D I/O and A/D Conversion, so I let someone else worry about building displays and just connect the cables lol.

Any further info about LED/OLED that you can share? Hit my email link in the post please. I love to geek out with this sort of thing, and now you have piqued my interests :)

I suppose this is also an extremely common-sense suggestion, but one thing I do to try to stretch s charge out as long as possible is that I always sleep my phone automatically once I know I'm done with it. I leave the timeout option at 1 minute, so that I don't have it going to sleep when I pause briefly. But by sleeping it on my own when I'm done, it becomes habit after a while and every little bit helps.

Great article and very helpful.

Just one question - I use Screebl and I really like it for what it does but I also have the screen timeout set to 15 seconds. Does Screebl really help to save battery life?

I like the idea behind Screebl. But I've not seen any real improvement by using it. IMO the app running in the background seems to use as much battery as it's saving in other areas.

Since you're using it, try for a week with and a week without and see how it works for you? Post your findings in the forums and expect some lively discussion ;)

Everyone's usage is different, and it may do great for you. I always try NOT to say anything negative unless I see actual negative results. Screebl doesn't use MORE battery when I use it, so I can't say anything bad about it. :)

Dark or light wallpaper will not matter. The screens on cell phones are either lit or they're not. Lcd screens just block light to create dark areas with the same amount of light being put out. Its almost like closing window blinds to block sunlight. The shade of wallpaper WILL NOT change battery life.

Great article, helped me figure out why my N1 was switching from 3G to wifi when the phone screen went to sleep. I thought it was my router acting up and giving me poor wifi signal in the house!

I tried the always-on Wifi trick this weekend, when I was mostly home, and it made a HUGE difference in battery life. I'm now trying it at work--which should have the additional advantage of staying attached to my 1x network. Before, when it shut off, it would disconnect, and then always reconnect to our open network--which requires a captive portal to log in, so often it's unable to update email, etc. Ideally, I'd be able to priorize the 1x connection, but it seems Android prioritizes by alphabetical order. I've thought about changing the SSID on the 1x network to put "aaa" in front of it but that would break everything else ;-).

Suggesting that you should hook your phone to the charger before you go to bed and leave it there all night is terrible advice. It only takes 2-3 hours to fully charge a battery, and having it plugged in those extra 4-6 hours is not very eco friendly, and it's certainly not friendly to your wallet in the long run, either. Didn't you know that a charger will consume the same amount of energy even though the battery is fully loaded? It even consumes as much energy when it's not plugged into a device at all, but still connected to a socket outlet.

Great article thank you very much.
I would also recommend...
1)Turn off Bluetooth when you are not using it. It looks to me that having it on, even when the phone is not paired, is a drain
2)Check the background polling interval on apps and reduce them to your personal minimum requirements (i.e. I do not need Facebook and Twitter refreshing every 15 min. Every few hours is good enough for me in the background and when I'm in the app reviewing updates, I can tap refresh)

You can Google in black on your phone at http://bGoog.com to extend you battery life too and to use less bandwidth! The black background definitely saves power on my phone and it looks cool too.

DSpencerS:
A Black Google doesn't save much energy with current screens. For that Google Black approach you have Blackl http://www.blackl.com which uses renewable energy and small data transfers. For the screen itself a Black Google will not save that much energy for now.

I am running CM7 nightlys / .37incedikernel (w/smartass) and I have it set to 128 screen off and 921 screen on (also to save battery)... my question is, when is it a good idea to wipe the battery stats and why? I usually wipe the Dalvik cache every few days too...

Device(s): HTC Incredible
ROM/Kernel: CM7RC1#6/.37incredikernel

Check the magnetic clasp on your case. If you have battery problems and it is hot when you pull it out of the case, it could be turned on by the magnet. This doesn't happen if I turn my phone FACE IN when I put it in the case but can happen if I turn it FACE OUT!

HTC EVO Shift

Nice catch, thanks for this. I had wondered why something triggered on the phone even though I almost always turned it with the screen away from the magnetic clasp. Ralph L. Seifer, Long Beach, California.

I have a hTc one and it overheats too quickly, while I was reading the tips and tricks , I unlocked it for a couple seconds , went to the settings to find something , and put it on my lap , in about 3 minutes it was burning up , can anyone help me ?

The tips and facts given in this blog are very informative and useful. I am agreed with all the concepts and facts. If we are using phone with an LED screen, dark wallpapers, we should use less battery to display than light.

Regards,
http://aeaccessories.com/

My phone has suddenly decided to start with the negative charging. i plug it in and instead of showing me increase in the battery meter it spirals down. the battery drain is more than you can imagine...from 100% to 39% in less than an hour. besides my phone is also running like a sloth after the new update to 4.2.could you please please help out?
Thanks...