If there are ANY PlayStore updates pending/available the battery drains extremely fast. Once I complete the pending/available updates the battery use returns to normal.
Welcome to Android Central! Is it only while the apps are in the process of updating/installing, or does the battery drain even when it's waiting for you to tap the Update button? App installation can use a fair amount of power -- this is evident when setting up a new phone (or after a factory reset), when all of your apps are installing. The phone can get pretty warm, and the battery level can drop fairly quickly.