Now that the Verizon version of the Samsung Galaxy Nexus finally got the Android 4.2.2 Jelly Bean update, there's a number of folks out there with some serious complaints about battery life. If you're one of the unlucky folks affected, you know exactly what I mean. If not, a quick look across the Internet will get you up to speed about the troubles these folks are having. Make no mistake, it's a real issue.
Now you'll need to keep in mind that the Verizon Nexus is one of those early LTE devices that will never have stellar battery life, but plenty of folks have found a way to get back to where they were before the OTA (in regards to battery life). Their secret? A factory reset. It's something that nobody ever likes doing, but sometimes you have to bite the bullet and just do it. We'll discuss why, and talk about how it's done after the break.
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Why do I need to factory reset?
Let's pretend that your phone has Android version 1 running on it. This is a hypothetical number, and has nothing to do with any real version, but we're going to use it because it's a simple, easy to read numbering system. You're happily rolling along, running version 1, and your phone is creating data. This data gets saved -- sometimes forever, sometimes it's just cached. The important thing to remember is that you have a bunch of data that Android version 1 uses to operate.
Monday, you got a notice to update to Android version 2. It's all new and exciting, and you've been waiting for it for a while. So you do it. What you're downloading will overwrite all your system files and Google applications with version 2, but it won't touch the data version 1 created.
When it restarts, you have a brand new system using version 2, using data created by version 1. Most times, this is fine. Other times, it causes issues. This depends on the data itself, what it is doing, and how much the structure has changed from version 1 to version 2. It's not bad coding, or bad apps, though sometimes those happen, too. It's the way things may have been moved in database tables, or new entries that get created incorrectly, or old data that gets moved to the wrong place. It happens.
If you do the whole custom ROM thing, you know about wiping between flashes. If you don't, just know that the more things change in the system files, the higher the chance that your phone is going to act a little wonky using that old data. One of the things usually affected is battery life. As a general rule, the bigger the changes to the OS, the higher the likelihood that things can go wonky. In this case we're talking Android, but you'll find the same issues on iOS, Windows, Mac OS, Linux, and any other advanced operating system. And the bump to 4.2.2 was a pretty big change.
Protip: If you're an advanced user, you can possibly get away with seeing just what is killing your battery and manually clearing that data and cached data. This is hit or miss, but the option is there.
How to factory reset?
It's pretty straightforward. The first thing you'll want to do is back up anything you want to keep from your internal storage. This includes pictures, movies, music, and any personal documents. Just plug your phone into a computer (or use a wireless transfer application, like Airdroid or Wifi File Transfer) and copy the files you want to keep to a folder on your desktop. Once you're sure you have everything backed up, delete everything else. You don't want any errant data left on the internal storage to influence your newly wiped system when you reboot. Don't worry about the folders, Android will recreate what it needs.
If you have a custom recovery, boot into it and choose the factory reset option. You've likely done this before.
If you phone is stock, go into Settings > Backup & reset. You'll see a menu item that says "Factory data reset; Erase all data on phone". Tap it. That takes you to a warning screen reminding you that you'll lose everything, including all the data you've accumulated for accounts you're logged into. That's exactly what we want to happen. Tap the Reset phone button at the bottom, and wait.
When your phone reboots, go through the sign in process again. Apps may or may not begin to download, depending on your backup and restore settings. That's OK, let them install and let things settle down and get synced. Then copy the files you backed up back to the phone.
Hopefully, this will fix the battery life issues you've been seeing. As always, if you have questions or want to share your experiences, jump into the forums!