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.