I've searched for 3 days now but didn't find a solution or similar problem/question anywhere else. Here is the deal: Trigger in 1 hour - works correct Trigger in 2 hours - Goes of in 1:23 Trigger in 1 day - Goes of in ~11:00 So why is the AlarmManager so unpredictable and always too soon? Or what am I doing wrong? And is there another way so that it could work correctly? This is the way I register my PendingIntent in the AlarmManager (stripped down): AlarmManager alarmManager = (AlarmManager)parent.getSystemService(ALARM_SERVICE); Intent myIntent = new Intent(parent, UpdateKlasRoostersService.class); PendingIntent pendingIntent = PendingIntent.getService(parent, 0, myIntent, PendingIntent.FLAG_UPDATE_CURRENT); //Set startdate of PendingIntent so it triggers in 10 minutes Calendar start = Calendar.getInstance(); start.setTimeInMillis(SystemClock.elapsedRealtime()); start.add(Calendar.MINUTE, 10); //Set interval of PendingIntent so it triggers every day Integer interval = 1*24*60*60*1000; //Cancel any similar instances of this PendingIntent if already scheduled alarmManager.cancel(pendingIntent); //Schedule PendingIntent alarmManager.setRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP, start.getTimeInMillis(), interval, pendingIntent); //Old way I used to schedule a PendingIntent, didn't seem to work either //alarmManager.set(AlarmManager.RTC_WAKEUP, start.getTimeInMillis(), pendingIntent); It would be awesome if anyone has a solution. Thanks for any help! Update: 2 hours ago it worked to trigger it with an interval of 2 hours, but after that it triggered after 1:20 hours. It's getting really weird. I'll track the triggers down with a logfile and post it here tomorrow. Update: The PendingIntent is scheduled to run every 3 hours. From the log's second line it seems like an old scheduled PendingIntent is still running: [2012-5-3 2:15:42 519] Updating Klasroosters [2012-5-3 4:15:15 562] Updating Klasroosters [2012-5-3 5:15:42 749] Updating Klasroosters [2012-5-3 8:15:42 754] Updating Klasroosters [2012-5-3 11:15:42 522] Updating Klasroosters But, I'm sure I cancelled the scheduled PendingIntent's before I schedule a new one. And every PendingIntent isn't recreated in the same way, so it should be exactly the same. If not , this threads question isn't relevant anymore.