On Google Android, running on my T-Mobile G1, there is a icon which appears in the notification bar whenever the phone is syncing Gmail, Calendar, Contacts, etc. Typically this icon only appears for a second or two and then goes away. However, a week or so ago I began noticing that my G1’s battery was being completely exhausted at least daily, and quite often I’d pick up the phone to find it very hot with the sync icon stuck on. The warmth seemed to be caused by the radio being constantly in use for extended periods of time as sync tried to occur. While I could deal with the sync not always working right or my having to cancel an in-progress sync, having to charge the phone a few times per day was becoming a big problem.
My short-term workaround was to leave the phone on the charger overnight and allow it to sync then, which seemed to work. However, this was obviously not a solution. Yesterday I finally took time to look into the problem. To start, if I entered Settings → Data Synchronization, the Application sync settings portion would often indicate that sync hadn’t occurred for a day or two. When I manually initiated a sync I noticed that while Gmail and Contacts synced and completed reasonably fast (a few seconds each), the Calendar sync seemed to start and stop repeatedly, never finishing during the time I watched it.
Signing into Google Calendar, which I don’t do very often, showed the error above, stating that …this is not a Calendar user: http://firstname.lastname@example.org/public/basic. This calendar is a Google AdSense calendar found on this page within the AdSense help documentation, entitled How do I subscribe to the AdSense Calendar. After removing the entry for this seemingly broken calendar from my Other calendars list I initiated another sync from the phone (Settings → Data Synchronization → MENU → Sync now) and it all syncing completed within 30 seconds.
If one visits the page from which the aforementioned AdSense calendar is linked, the link is still active, but attempting to add the calendar results in this error. Since I’d added this calendar without error a while ago, I suspect that once it became unavailable the phone was unable to promptly complete a calendar sync, having to wait for something to time out before it could complete. Unfortunately, until this timeout the radio was active, which ate battery and caused the phone to warm up.