• After 15+ years, we've made a big change: Android Forums is now Early Bird Club. Learn more here.

Root [ROOT] Using SetCPU + Perflock Disabler to Save Battery, Underclock

pingpongboss

Android Enthusiast
Apr 19, 2010
541
278
I'm sure many people has seen the thread where OverclockWidget was claimed to have increased the battery life for some people. Near the end of the thread I became skeptical and proved that it had in fact no effect on the CPU speeds at all, and so can not save battery life. Well, good news is that a new function in the competing SetCPU app will now get you a real, tested increase in battery life.

According to my tests, my Evo with the screen off should theoretically get a 64 hour battery life!

CAP201007081101.jpg


Know what you're doing? Short version: Get latest SetCPU (version at least 2.0.0) and use Menu -> Perflock Disabler in the Main tab to enable underclocking.

Don't know what I'm talking about? Good, follow this tutorial:

Prereqs:
  • You need to have ROOT. Unrevoked root method is confirmed to work, and so is Toast's root method. Usually I wouldn't recommend using Unrevoked, but it's just so fast to set up, and perfect for those who have no clue what ROOT means.
  • Buy SetCPU from the market, or download it from XDA forums for free. Please support the developer of this incredible app! The version must be at least 2.0.0b
  • Be on the STOCK kernel. If you're on a custom kernel, chances are that perflock has already been disabled, and you won't need this tutorial to underclock. Some custom ROMs come with the stock kernel (like Fresh 0.5.3) and some don't (like Baked Snack .9.6)

Alright, got the prereqs down? Lets start this.

HOWTO:
  1. Open SetCPU and give it root permissions as necessary. As a control, go into the Info tab and do the Long Bench a few times. You should get around 1000ms.
  2. Go to the Main tab, hit MENU, hit Perflock Disabler (read the warning!), and hit Disable Perflock Beta: May crash!
  3. It will work for a while, and then say it's successful. You can then click the X on the top right to exit the Perflock Disabler.
  4. Go into the Main tab and drag Max: all the way down to 245000 (245Mhz). Make sure the green xxx max xxx min label above the sliders show 245 for both and also disable any Profiles you've set. Go to Info tab, then hit Long Bench again. This time you'll get something ridiculous like 5000ms, meaning that the Perflock Disabler has worked!
  5. Change your settings Profile tab to something similar to my settings. You can mess around with the Battery < xx% profiles to fit your needs. Your exact Profile priorities do not matter, it's only important that some have HIGHER priority than others. On the Main tab, set Max all the way to the right (998400) and Min all the way to the left (245000), Scaling to ondemand, and check Set on Boot. Do not check Set on Boot yet if you're the super careful kind. You can check it later when you've tested that your phone isn't crashing
    CAP201007110008.jpg

    The last entry is Battery < 100%, set at lowest priority, with MAX as the highest value, MIN as the lowest value, and scaling as ondemand.

Congratulations you're now able to underclock your Evo!

Comparison:
The only applicable parts is after the charging finishes (after the solid green bar ends)

Before Perflock Disabler:
CAP201006050021.png


After Perflock Disabler:
CAP201007081156.jpg

See that little dip at the end? That's when I was turning the screen on and messing with the phone for this tutorial. What a difference.

Disadvantages:
  • Yes, not everything is happy and pretty. As the Perflock Disabler warning says, you HAVE to apply the Perflock Disabler on every boot. If you forget, then your SetCPU settings will have no effect on the Evo. Install a custom kernel that already has Perflock disabled if you do not want to do this on every boot.
  • Also, since this clocks the Evo down when the screen is off, you may get a slight (super slight!) delay when you turn the screen back on. This is because the profile changes from Screen Off to Battery < xx% and SetCPU needs to clock the CPU from 245mhz to 998mhz.

FAQ:
What is Perflock Disabler?
HTC added a "perflock" in their stock kernels to prevent over/underclocking. SetCPU's Perflock Disabler, like its name implies, disables this restriction.

How come your screenshots show that you can go down as high as 1.19Ghz and as low as 128Mhz?
I'm using this custom kernel.

Will this work with OTA update xxx.xxx.xxx.xxx?
Yes, as long as you have root, and don't lose it when you update (do your research!) then this will work.

What are your settings?
Wifi ON, Bluetooth OFF, GPS ON, Mobile network Data OFF (ATT contract with dumbphone still not over), Screen Timeout 1MIN, Brightness AUTO, Advanced Task Manager set to SAFE kill tasks when screen is off.

What is that cool looking battery monitoring app?
That's SystemPanel, paid on the market. A free alternative is JuicePlotter, also on the market. Screenshots were taken with Drocap2.
 
Excellent walkthrough...good to see it all in one place. I had everything set the same way from your reply on the other thread, but this let me double check everything.

Perflock disabled works on Fresh 0.5.

Testing battery life today.

Interesting, I assumed that all custom ROMs included a custom overclockable kernel, but after reading Fresh's changelog (PowerTOP section) again I'll have to revise the prereq part.
 
Upvote 0
SetCPU on... I'm running Damageless Rom v3.2.3.
Custom Kernal for Nova Screen FPS Fix and undervolt configurations.

phones was charged to 97% when i took it off the charger.

My phone has Bluetooth, 3G, GPS, and Brightness at 25%. Off the charger for 2 hrs and 53 mins with 3 phone calls at about 5 min each. Browsed the web and received email. I'm currently @ 93%
 
Upvote 0
SetCPU on... I'm running Damageless Rom v3.2.3.
Custom Kernal for Nova Screen FPS Fix and undervolt configurations.

phones was charged to 97% when i took it off the charger.

My phone has Bluetooth, 3G, GPS, and Brightness at 25%. Off the charger for 2 hrs and 53 mins with 3 phone calls at about 5 min each. Browsed the web and received email. I'm currently @ 93%

Some people from XDA have been saying that setting sleep at 245Mhz has been giving them better battery life than 128Mhz for whatever reason. Think I'm gonna test it a bit further to get the sweet spot.
 
Upvote 0
Some people from XDA have been saying that setting sleep at 245Mhz has been giving them better battery life than 128Mhz for whatever reason. Think I'm gonna test it a bit further to get the sweet spot.

i have my sleep set at 245mhz, and it's eliminated any lag I was getting when I would wake up the phone when it was set at 128mhz during sleep
 
Upvote 0
Thank you for sharing this. Running FreshToast100b1 and incorporating your settings as a starting point. I'll report back with battery life. Thanks again.

Side note: Running Toast kernal, while attempting to disable Perflock, SetCPU reported back that Perflock was not present, no need to disable. Nice feature.
 
Upvote 0
Thank you for sharing this. Running FreshToast100b1 and incorporating your settings as a starting point. I'll report back with battery life. Thanks again.

Side note: Running Toast kernal, while attempting to disable Perflock, SetCPU reported back that Perflock was not present, no need to disable. Nice feature.

Ah, yes. I believe thatkernel is configured to be overclockable by default.
 
Upvote 0
Thanks to the OP for the writeup. I use this with Setting Profiles, and I am seeing some amazing battery times. Setting Profiles has a bunch of features of Locale, with out the big price tag.

Also, instead of clocking all the way up to the top, I have mine set to 768, and if the battery drops below 45%, I have it slowing down more to stretch the battery.
 
  • Like
Reactions: sag7392
Upvote 0
Thanks to the OP for the writeup. I use this with Setting Profiles, and I am seeing some amazing battery times. Setting Profiles has a bunch of features of Locale, with out the big price tag.

Also, instead of clocking all the way up to the top, I have mine set to 768, and if the battery drops below 45%, I have it slowing down more to stretch the battery.

Nice, that's a great way to fully extend battery life beyond what this tutorial does.
 
Upvote 0

BEST TECH IN 2023

We've been tracking upcoming products and ranking the best tech since 2007. Thanks for trusting our opinion: we get rewarded through affiliate links that earn us a commission and we invite you to learn more about us.

Smartphones