I believe SDM is related to OTA updates (see posts below). Not sure why it's causing a problem though; phone trying to frequently check for updates? Did you install the latest OTA (I605VRALL4) recently or still on original stock firmware (I605VRALJB)? To check go to Menu, Settings, About Phone, Build number.
Actually I keep deferring the update because I want to set aside time to root. Do you think it's constantly checking for updates and killing my battery?
Sent from my SCH-I605 using Xparent Green Tapatalk 2
It does sound like the OTA updater is triggering frequently preventing the phone from going into a deep sleep and subsequently causing increased battery drain.