Same issue with battery drain. Samsung Galaxy S2, Android 4.0.4, I'm not a heavy user (not even on a data plan at the moment), so my battery usually lasts easily a day, and maybe two. Now it's barely getting through one day. Looking at Battery settings, BitTorrent Sync used 79% of last period (charge cycle?); far beyond the next contender, Google Maps at 11%. 8.5h on that charge. Looking at details for BitTorrent Sync, v1.1.27: CPU total is 3h 47m, data sent 810bytes, received 1.49KB. I only started testing this app, so I'm syncing only one folder containing one very short text file. I had automatic sync on; I'll turn it off for a while and see if battery life improves. EDIT: I'll add one additional note. The folder on the phone that BTSync is watching is on an external SD card.