Using SetCPU to boost battery life on rooted HTC EVO
This guest post was written by Joseph Davenport.
What's the one thing that every HTC EVO owner wishes they could fix about their device?
Battery life.
In addition to following G&E's battery tips, you can also dramatically increase the battery life of your EVO if you're rooted. You will need SuperUser permissions to do this, and a good custom kernel couldn't hurt either. This method does not include the controversial trickle charge, but as fair warning, check to see if the kernel that you're running has Superior Battery Charging (SBC) just in case. It will, however, include use of a fantastic little program called SetCPU for Root Users by MichaelHuang.
Most root users are already aware of SetCPU and it's one of G&E's must-have root apps, so this post is at those who new to the root scene or unfamiliar with the app.
One of the great things about SetCPU is that it has the ability to set up profiles that underclock the processor under certain conditions. SetCPU can also be used to overclock your processor, but you'll need a custom kernel to do that. Underclocking the processor can be done without using a hopped-up kernel, and it doesn't matter if you're running a Sense or AOSP ROM. Note: You may to disable Perflock to use SetCPU on a Sense ROM, but every ROM is different. To do this, hit Menu > Perflock Disabler on the main screen.
On that initial screen, you'll have the option to autodetect the speeds that your kernel is capable of. You're going to want to do that.
Next, you'll see two bars with the maximum and minimum speeds that your processor will hit when there is no other profile active (more on profiles in a minute). The maximum is limited by your kernel. The minimum is always 245Mhz, or at least it has been on every ROM/kernel combo I've ever used.
You can set the maximum to any value you like, and your EVO will never exceed that. On the dropdown box, you'll see a series of governors. Use "conservative" (if available) for the best battery life because it will make your processor immediately scale back down to the minimum speed when under a light load.
You're also going to see a profiles tab at the top of the app. A necessary profile to have is the "Screen Off" profile. Why would you want your EVO running at top speed when you aren't using it? I set my processor to run at a max of 422Mhz when the screen is off, and I set a high priority on that to make sure that no other profile takes over. You can set up various profiles, but the most important thing is that the "Screen Off" profile has the highest priority.
You can play with the settings to your liking. I boosted my EVO's battery life dramatically using SetCPU. Give it a try on yours and let us know how it goes.
This guest post was written by Joseph Davenport (J.D.), editor-in-chief of The Tech Councillor.
