Re: Best methods for conserving/extending Droid 4 battery life?
You don't need a custom ROM to toggle 4G.
It's not a regular menu option anymore, but you can use one of two free apps - LTE OnOff or Phone Info - to get into the internal menu for the phone.
Then, scroll down to the menu which should be set for "LTE/CDMA/EvDo" if the phone is in 4G.
Selecting "CDMA only (PRL)" gets you into 3G after a short wait, and go back to "LTE/CDMA/EvDo" to 4G.
This has made battery life actually reasonable. The phone is still pretty fast in 3G, and I don't need it to be in 4G if it's in my pocket doing background syncing.
I generally stay in 3G on battery all the time, unless I know I need 4G for something. I turn 4G back on full time if I'm plugged in.