Even RTC_WAKEUP doesn't help most of the times.
Solution that worked for my app when device in deep sleep mode:
Use WakefulBroadcastReceiver combined with AlarmManager.
Service is started by startWakefulService() and when it is finished, it releases the wake lock by calling completeWakefulIntent(intent). So the device will be allowed to go back to sleep.
I'm not adding any code. Search for examples on how to use WakefulBroadcastReceiver with AlarmManager. Even WakefulBroadcastReceiver doc has some template code.
Also reduce the frequency of alarm so you can avoid draining so much battery.
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