Linked by snydeq on Wed 2nd Nov 2011 22:50 UTC
Google InfoWorld's Serdar Yegulalp provides a look at the best apps for boosting the battery life of your Android device. "The best place to start if you just want to survey your power usage habits is Battery Indicator. To follow that up with actual power management, Green Power and JuiceDefender are your best bets. 2x Battery is not a bad program, but it's limited to managing cell data and not Wi-Fi connections. If that feature were added in a future revision, 2x Battery would be a real contender."
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Comment by stabbyjones
by stabbyjones on Wed 2nd Nov 2011 23:43 UTC
stabbyjones
Member since:
2008-04-15

*menu* -> "Settings" -> "Display" -> "Brightness" -> Tick "Automatic Brightness"

Disable wireless when you aren't using it. (On Cyanogenmod)
*open notifications* -> tap the wireless icon.

That alone makes my Galaxy S2 last twice as long as it usually does.

The notification power widget in Cyanogenmod means you can control pretty much everything that uses battery from your notification pulldown. I use wireless, GPS, Bluetooth, sound, rotation and screen timeout on mine.

Reply Score: 3

RE: Comment by stabbyjones
by broken_symlink on Thu 3rd Nov 2011 00:10 UTC in reply to "Comment by stabbyjones"
broken_symlink Member since:
2005-07-06

i also disabled background data and have juicedefender enable it every 2 hours between 10am and 12am.

Reply Score: 2

Conditional underclocking
by Shmoopty on Wed 2nd Nov 2011 23:50 UTC
Shmoopty
Member since:
2011-01-03

I've found SetCPU to be the best battery saver beyond any of those recommended apps.

It will allow your CPU to be progressively underclocked when it reaches certain battery levels if your phone is rooted.

At 30% battery, my phone becomes slow. At 15%, it becomes *very slow*.

Because slow is always better than dead, and the net effect is significantly longer battery life.

Reply Score: 1

RE: Conditional underclocking
by Alfman on Thu 3rd Nov 2011 05:11 UTC in reply to "Conditional underclocking"
Alfman Member since:
2011-01-28

Shmoopty,

"I've found SetCPU to be the best battery saver beyond any of those recommended apps. It will allow your CPU to be progressively underclocked when it reaches certain battery levels if your phone is rooted."

I don't have an ARM processor to test this on, but I hear that these processors are extremely aggressive in conserving power when they're not in use. This way, when they're idle, they should have a similar energy footprint regardless of clock speed. And when they're busy, the clock speeds are inversely proportional to the length of time spent being busy. So slowing down the clock isn't necessarily more efficient.


Here is data from a test I just completed on my Intel Xeon 3.00GHZ E3110.

A simple work load: ( 21.5B loops )
xor ax, ax
xor bx, bx
xor cx, cx
again:
add ax, 1
adc bx, 0
adc cx, 0
cmp cx, 5
jb again
int 20h

3GHZ Throttling enabled:
Idle = 5.2watt
Workload = 16.5watt for 23s = .105 watt-hours

3GHZ Full throttle:
Idle = 6.6watt
Workload = 17.6watt for 22s = .108 watt-hours

2GHZ Throttling enabled:
Idle = 5.1watt
Workload = 9.1watt for 98s = .248 watt-hours

2GHZ Full throttle:
Idle = 6.6watt
Workload = 17.6watt for 33s = 0.161 watt-hours


I can't explain what went on with cpu throttling at 2GHZ, a guess is that maybe it wasn't designed to work with an underclocked CPU? Never the less, take note that in all instances (with and without dynamic throttling), the CPU clocked at 3GHZ was more energy efficient under load than when it was clocked at 2GHZ. Interestingly the 2GHZ throttled test used the lowest wattage but required the greatest total energy because it was so slow. At idle, the cpu frequency made no difference, as I anticipated.

So, if the CPU's idle energy footprint is the same regardless of clock speed, then it may make the most sense to empty the work queues as quickly as possible to return to idle.

Comparing this to ARM processors is obviously apples to oranges, but it should provide a good warning against taking improved energy/frequency ratios for granted.


Can anyone shed light on empirical data for ARM processors specifically, like those used in Android phones?

Edit: I should add that my test didn't play with voltages levels, which were left at auto. The cpu throttling utility for my mainboard is supposed to do that, though I'm not sure exactly what it does since it's been end-user dumbified.

Edited 2011-11-03 05:30 UTC

Reply Score: 4

RE[2]: Conditional underclocking
by JAlexoid on Thu 3rd Nov 2011 09:45 UTC in reply to "RE: Conditional underclocking"
JAlexoid Member since:
2009-05-19

You can't compare a workstation CPU with highly optimised low power usage CPU. Too different architectures and other stuff.

Did you factor in the OS into your tests of Xeon? Because that makes a lot of difference. Specially in the more is less case.

Reply Score: 2

RE[3]: Conditional underclocking
by Alfman on Thu 3rd Nov 2011 10:27 UTC in reply to "RE[2]: Conditional underclocking"
Alfman Member since:
2011-01-28

"You can't compare a workstation CPU with highly optimised low power usage CPU. Too different architectures and other stuff."

I thought I said that, but yeah.


"Did you factor in the OS into your tests of Xeon?"

No I didn't. Just now I tried the test at 3GHZ and there was no difference in execution speed between linux and windows. I could not measure the cpu wattage under linux, but I have no reason to believe it'd be different in the same state.


"Because that makes a lot of difference. Specially in the more is less case."

Can you clarify what you mean? Obviously anything that places a load on the scheduler, such as interrupts, will be very os dependent. However if interrupts are consuming less than 1% of CPU in either OS, then the test loop given above should (and does) run equally fast under either OS. If I had stressed memory or IO then things might start to diverge.

Reply Score: 2

RE: Conditional underclocking
by 2shanfernando on Thu 3rd Nov 2011 10:39 UTC in reply to "Conditional underclocking"
2shanfernando Member since:
2008-02-01

+1 for SetCPU or CPU Tuner for the adventurous rooters. The former is free for XDA-Developers but well worth a donation for his efforts!

Reply Score: 0

RE[2]: Conditional underclocking
by phoenix on Thu 3rd Nov 2011 16:36 UTC in reply to "RE: Conditional underclocking"
phoenix Member since:
2005-07-11

SetCPU shouldn't be needed on most modern devices running Android 2.3. CPU speed should be automatically controlled by default now. At least, it is on my Xperia Pro, as shown by System Monitor (goes as low as 200 Mhz and various steps up to the max of 1 GHz).

SetCPU isn't needed with Cyanogenmod 7.x either, as similar features are built in.

About the only time you need SetCPU anymore is if you are going to overclock the CPU.

Reply Score: 2

Classical conditioning ;p
by zima on Wed 9th Nov 2011 23:52 UTC in reply to "Conditional underclocking"
zima Member since:
2005-07-06

I've found SetCPU to be the best battery saver [...] At 30% battery, my phone becomes slow. At 15%, it becomes *very slow*. Because slow is always better than dead, and the net effect is significantly longer battery life.

Probably mostly because it acts as a signal / limiter for you, to use it much less (while, per task, possibly actually using more power)

When people become (almost) obsessed about some goal desired by them, about tricks supposedly leading to it - they often overlook how much, during search for the holy grail, they modify their own behaviour (and, subsequently, lead themselves to feedback loop, reinforce their self-perception that tricks work)

Reply Score: 2

So sad
by WorknMan on Thu 3rd Nov 2011 09:07 UTC
WorknMan
Member since:
2005-11-13

It's pretty sad that we have progressed this far with tech, but the battery technology isn't keeping up, so we have to resort to all of these dumb workarounds. Can you imagine having a battery that would allow you to run a smartphone or tablet for a week or more without ever having to charge it?

As it stands, heavy users can hardly make it through a work day on a single charge. And if you have a 4g phone, you pretty much need a nuclear accelerator strapped to your back ;)

Reply Score: 2

RE: So sad
by JAlexoid on Thu 3rd Nov 2011 09:46 UTC in reply to "So sad"
JAlexoid Member since:
2009-05-19

Can you imagine having a battery that would allow you to run a smartphone or tablet for a week or more without ever having to charge it?

It's called ePaper and we don't want to use it.

Reply Score: 3

RE: So sad
by phoenix on Thu 3rd Nov 2011 16:42 UTC in reply to "So sad"
phoenix Member since:
2005-07-11

What I don't understand about phone manufacturers is the puny size of the battery in most phones. You have a 4+" diagonal case, yet a 2" square battery. It's always boggled my mind that the battery isn't the same size as the back cover of the phone.

What's even more amazing to me is that there isn't an aftermarket for custom batteries for phones that cover the entire back of the phone. Sure, it would make the phone a few mm thicker. But it would be worth it to get several days of use out of them.

Reply Score: 3

RE[2]: So sad
by zima on Wed 9th Nov 2011 23:40 UTC in reply to "RE: So sad"
zima Member since:
2005-07-06

Most people / carriers probably wouldn't want to pay for "too capacious" (for those who just connect the phone to the charger, overnight, every night or two) battery. Always-physically-smaller-than-the-phone batteries also allow reuse in many models of handsets (variants of Nokia BL-5 are used in everything from Nokia 1100, 1280, etc. - giving there typical times between recharges on the order of a week or two - to many of their smartphones), bringing more economies of scale.
(and it's not really like the rest of internal space is wasted)

3rd party back-batteries could be a challenge to do ~reliably, if the phone wasn't meant for such (I know one that was: http://en.wikipedia.org/wiki/Nokia_5110 somewhat visible in http://commons.wikimedia.org/wiki/Category:Nokia_5110 - a bit of a brick, overall ;p ). But BTW, there are 3rd party auxiliary batteries which connect via the charging ports of handsets; probably good enough in a bag, at least.

Edited 2011-11-09 23:42 UTC

Reply Score: 2

Facebook app is a battery hog
by JAlexoid on Thu 3rd Nov 2011 09:40 UTC
JAlexoid
Member since:
2009-05-19

If you're a Facebook user then be ware of the official app. It's really, really bad at managing power.
I say, rip it out with it's guts and throw it dying on the road. The half-*****ed port from iOS does not deserve the mandatory inclusion with the OS.

Reply Score: 2

Comment by _xmv
by _xmv on Thu 3rd Nov 2011 13:34 UTC
_xmv
Member since:
2008-12-09

most of these apps are largely placebo. in fact most of them use more battery than they save.

its funny, because its based on this human feeling that "you must add stuff so that its perfect, better than stock, it must help, etc" but in fact it just makes things worse.

as the first reply says, just say brightness lower, thats the one setting that actually changes something.
(on some screen changing the screen filter also helps, but who wants a red screen?)

the cpus are extremely well throttled on the hardware side and using setcpu only makes the phone slower. undervolting also brings very little difference at this voltage/current.
when the phone is slower is just takes longer to finish the task, thus screen stays on longer, and screen is by VERY VERY VERY VERY VERY VERY, VERY FAR the number one thing that consumes battery. Did i say very ? oh yeah i did.


then the 2nd thing are shitty background apps. don't install shitty apps ;-)
the phone MUST deep sleep when its not in use and only rarely wake up (to check mail etc). if your phone is never entering deep sleep when screen is off, you have an issue. You can check deep sleep status in the android stock's battery information (in the settings) and even see what app is at fault.

Edited 2011-11-03 13:36 UTC

Reply Score: 5

3G/4G is the real enemy
by elsewhere on Thu 3rd Nov 2011 17:50 UTC
elsewhere
Member since:
2005-07-13

Make sure that wifi is set to remain active even when sleeping. This keeps your phone off of 3G for things like checking email etc. when your phone is at rest (ie. at home.)

If you do need to stretch the battery life throughout the day, disable 3G altogether. Makes a big difference, and edge is sufficient for background needs like email, weather updates etc. If you need bandwidth, re-enable it at will. Did this on my wife's old iPhone and it almost "doubled" the battery life (in as much as the phone was still usable the next day if she forgot to recharge it at night) with little impact on her usage. She's already complaining about battery life on her new Infuse 4G, so I'll probably do the same again.

Also do so if you're in an area with spotty or no 3G service. The radio transmitter will burn through battery juice trying to find and/or maintain a 3G signal even if there isn't one to find. I was up in the boonies on vacation this summer, and while there was cell service, 3G was spotty and my phone wasn't even lasting the day, despite not really being used. Disabling 3G fixed that nicely.

Basically, anything you can do to reduce 3G/4G usage will have a dramatic impact on battery life. On any platform.

Reply Score: 1

RE: 3G/4G is the real enemy
by zima on Wed 9th Nov 2011 23:58 UTC in reply to "3G/4G is the real enemy"
zima Member since:
2005-07-06

This one should be becoming much less of an issue (heck, 3G has some features which allow it to sleep better; 2G negotiates connections much longer; also better spectral efficiency of 3G - and sure, the radio methods used by 3g require more oomph on the handset side / processing, but they had time to mature)

Probably, she did start using everything more frugally, when instructed about the "causes" and how to turn them on only when necessary; we typically miss the many ways in which we modify our own behaviour - might work as well the other way around than the fairly usual: when people have nice 3G smartphone, they use it more.

Edited 2011-11-10 00:15 UTC

Reply Score: 2

get a $30 phone instead
by unclefester on Fri 4th Nov 2011 11:25 UTC
unclefester
Member since:
2007-01-13

Buy a cheap feature phone instead eg Sony Cedar [550 hours standby and up to 12 hours talk time (2g)] - only $39 outright in Australia. They are also far smaller and lighter than smartphones and don't usually break if you drop them.

Reply Score: 3