Welcome to the ghost town that is this thread.
There are many settings that effect battery life.
Yes the Relay does go in to a sleep mode, but there are many settings
for when it goes in to sleep, what gets shut down and when. the list is
too long to post here, but since most of these settings are standard Android settings you can easily find them online.
Here's a link to help you get started:
Support - T-Mobile Cell Phones SGH-T699 | Samsung Cell Phones
I've heard people having problems caused by Power Saving Mode causing blue screen, so I may stay away from that. Look at items and apps that constantly check for updates (email, weather, etc.) These cause a lot of drain.
Also, obviously turning off bluetooth or wifi when not needed (or always on for wifi) help drastically.
Relay is not really different from other smart phones in terms of battery drain.
Good luck and let us know how you made out improving battery life.
