There have been reports of the LG Optimus G having poor battery life due to LG’s implementation of Fast Dormancy. Fast dormancy is a feature in devices that, after the device stops transmitting data of HSPA networks, waits for a signal from the mobile network telling it to close the connection, thereby saving battery, and you may have noticed the H or H+ signal turns to 3 or 3G when there’s no data being transferred.

However, it seems that LG botched the implementation of fast dormancy, which is keeping the device stay awake more than usual waiting for a signal to close down the HSPA connection after data transfer, resulting in more battery being used than normal, as the phone waits for an indication from the network longer than necessary.

A solution to this is to disable fast dormancy completely, and that’s exactly what the app Fast Dormancy Toggle by XDA forum member jonasl helps you do with a simple little toggle button, instead of having to disable it by manually editing system files. Many users have reported improved battery life after disabling fast dormancy, so it seems that keeping it enabled was indeed causing battery drain.

Follow the instructions below to install and use the app to disable (or enable Fast Dormancy):

  1. Download the app’s APK file from the source page.
  2. Copy the APK file to your Optimus G.
  3. Enable “Unknown sources” under the Settings » Security menu on the device, so that you can install apps manually.
  4. You will need to have a file manager installed to browse to and install the app manually. Download ES File Explorer from the Play Store or any other file manager app.
  5. Open the file manager and browse to where you copied the app’s APK file. Tap on the file, then select the Install button to install it on your phone.
  6. Run the app by clicking on the “FD Toggle” icon in the apps menu.
  7. Press the “Disable” button to disable fast dormancy. Then, reboot your Optimus G to let the changes take effect.

Fast Dormancy should now be disabled on your LG Optimus G and you’ll hopefully see improved battery life when using HSPA/3G data. Let’s hope LG fixes it in a future software update.