Undervolting my S4 with astonishing results

[nj4ck]

Hey forum,

 

just a little success story here. I've been playing around with the firmware of my Galaxy S4 I9505 the last couple of days and I appear to have made a game-changing breakthrough in regards to creating the perfect phone for myself. So it all started about 3-4 months ago, when I first decided I was sick of Touchwiz and finally rooted the device. I've always liked the "nexus-style" stock-android experience, so I turned my S4 into a Google Play-edition S4 by flashing the [insert super-long ROM name here]-ROM. I really liked it mostly, but I immediately noticed it was draining my battery FAST. Like, loosing 1% every minute-fast. Since I didn't have the nerve or time to play around with kernels and other ROMs at the time, I re-flashed the stock ROM and went back to using the device as I had used it before.

 

So now I recently decided to give Cyanogenmod 11 a try. I used the Cyanogenmod installer and it was done easily in just a few minutes. I absolutely LOVED the experience, but again, the battery was dying very fast and I could hardly get half a day of use out of it. Well, this time I decided I wasn't going to give up on it that quickly, and after some research, I decided to flash the Alucard Kernel and see what I could do with it. When you install the Kernel, you get an App called "STweaks", which I used to try some of the many CPU governors, some of which seemed to help battery life quite a bit. I ended up settling on just plain 'ol ONDEMAND for both CPU and GPU, with the max. CPU clock at 1.5GHz.

 

The real magic started when I began undervolting the CPU, though. I started by pulling back on voltage in small steps and using Antutu Benchmark to test stability, but quickly noticed that there was almost nothing I could do to make the CPU unstable. I did leave it up a few noches above minimum for the higher clocks above 1.2 GHz, but everything else is set to complete minimum. Idle @ 378 MHz used to be at .875V, now its at .825V. Boost clock @ 1566MHz used to be at 1.05V, now it's at 0.99V. The difference this makes is HUGE.

 

I have had 0 stability issues, but my battery life has seen a huge increase. Where I used to have only 5-7% left after a full day at work (on the stock ROM), I now have 35% left after the same amount of use. The phone hardly even gets hot anymore.

 

This has been my first time going this deep into the whole "rooting-flashing-undervolting-ect."-thing, and I am completely baffled by the results. Is my phone somehow a superb undervolter, or is this normal? And if this is normal, why doesn't Samsung give the CPU less voltage to begin with? It's currently 1:40 in the morning and my phone still has over 10% battery left. Under normal circumstances, it would have died 6 hours ago.

 

 

EDIT: I just pulled all the voltage levers back to absolute minimum and ran Antutu without any problems. Now running at 1.5GHz at .976V. This is amazing.

[_ASSASSIN_]

this is one of my favorite reasons for rooting, undervolting has actually made my M7 be able to last for well over a day with cyanogen.

[DavidTheWin]

As a Nexus 5 owner this intrigues me

[mansoor_]

I have had similar experiences with the s3,

touchwiz would only allow 12~16 hours of usage

cyanogenmod with slight undervolt and cpu  governor

and now it last 2 days!!

Essentially touchwiz is a mess,

samsung should feel bad for making it,

[PillowSmoke]

I should try this with my g2 and s2.

[nj4ck]

I should try this with my g2 and s2.

you definitely should

[Kyuubixchidori]

WHELP, time to play with stweaker on my slimkat s4. I will report back with results soon considering my phone always runs hot as ****. sometimes it has a serious battery drain, but other days it lasts ALL DAY. from a tech teenager. what. 

[Kyuubixchidori]

Stweak doesnt work with my kernel. any recommend app to change voltages? 

[Khêll]

cyanogenmod with slight undervolt and cpu  governor

hey, could you please explain how to use and install a cpu governor once cyanogenmod is installed?

 

thx a lot!

[nj4ck]

hey, could you please explain how to use and install a cpu governor once cyanogenmod is installed?

 

thx a lot!

Well I did so by flashing a kernel that came with a bunch of governors. 

[mansoor_]

hey, could you please explain how to use and install a cpu governor once cyanogenmod is installed?

 

thx a lot!

settings->build number->touch five times in quick succession to activate developer mode

settings -> performance -> processor & i/o scheduler 

if you want to know more about what these actually do read:

http://forum.xda-developers.com/showthread.php?t=1989824

[QLIMAX0147]

On 22/05/2014 at 12:46 AM, nj4ck said:

Hey forum,

 

just a little success story here. I've been playing around with the firmware of my Galaxy S4 I9505 the last couple of days and I appear to have made a game-changing breakthrough in regards to creating the perfect phone for myself. So it all started about 3-4 months ago, when I first decided I was sick of Touchwiz and finally rooted the device. I've always liked the "nexus-style" stock-android experience, so I turned my S4 into a Google Play-edition S4 by flashing the [insert super-long ROM name here]-ROM. I really liked it mostly, but I immediately noticed it was draining my battery FAST. Like, loosing 1% every minute-fast. Since I didn't have the nerve or time to play around with kernels and other ROMs at the time, I re-flashed the stock ROM and went back to using the device as I had used it before.

 

So now I recently decided to give Cyanogenmod 11 a try. I used the Cyanogenmod installer and it was done easily in just a few minutes. I absolutely LOVED the experience, but again, the battery was dying very fast and I could hardly get half a day of use out of it. Well, this time I decided I wasn't going to give up on it that quickly, and after some research, I decided to flash the Alucard Kernel and see what I could do with it. When you install the Kernel, you get an App called "STweaks", which I used to try some of the many CPU governors, some of which seemed to help battery life quite a bit. I ended up settling on just plain 'ol ONDEMAND for both CPU and GPU, with the max. CPU clock at 1.5GHz.

 

The real magic started when I began undervolting the CPU, though. I started by pulling back on voltage in small steps and using Antutu Benchmark to test stability, but quickly noticed that there was almost nothing I could do to make the CPU unstable. I did leave it up a few noches above minimum for the higher clocks above 1.2 GHz, but everything else is set to complete minimum. Idle @ 378 MHz used to be at .875V, now its at .825V. Boost clock @ 1566MHz used to be at 1.05V, now it's at 0.99V. The difference this makes is HUGE.

 

I have had 0 stability issues, but my battery life has seen a huge increase. Where I used to have only 5-7% left after a full day at work (on the stock ROM), I now have 35% left after the same amount of use. The phone hardly even gets hot anymore.

 

This has been my first time going this deep into the whole "rooting-flashing-undervolting-ect."-thing, and I am completely baffled by the results. Is my phone somehow a superb undervolter, or is this normal? And if this is normal, why doesn't Samsung give the CPU less voltage to begin with? It's currently 1:40 in the morning and my phone still has over 10% battery left. Under normal circumstances, it would have died 6 hours ago.

 

 

EDIT: I just pulled all the voltage levers back to absolute minimum and ran Antutu without any problems. Now running at 1.5GHz at .976V. This is amazing.

Can you please send me your voltage table with every single frequency?