Why class reminders arrive late on Android, and how to fix it
Short answer: on Android 12 and later, apps that are not allowed to set exact alarms have their reminders batched with other alarms to save battery, so a "10 minutes before" reminder can arrive several minutes late. Allow the app under Settings → Apps → Special app access → Alarms & reminders, then check battery and Do Not Disturb settings.
1. Exact alarms ("Alarms & reminders")
Since Android 12, an app needs the "Alarms & reminders" permission to ring at an exact minute. Without it, the system may deliver the reminder inside a window of several minutes. For class reminders that is the difference between on time and late.
2. Battery optimization and manufacturer app sleep
Doze mode delays most background work while the phone sits still. Exact alarms still ring, but some manufacturers add their own "sleeping apps" or "deep sleep" lists that block reminders entirely. If reminders still slip, remove the app from those lists.
3. Do Not Disturb and notification channels
If the reminder arrives silently, Do Not Disturb or a muted notification channel is the usual cause. Long-press the notification to see its channel and turn sound or pop-up back on.
4. Reminders after a restart
Android clears all scheduled alarms when the phone restarts or the clock changes. A well-behaved app re-schedules them on its own; if yours doesn't, open it once after restarting.
5. Vacations
The opposite problem: reminders ringing during the holidays. Pause them for the break instead of turning notifications off and forgetting to turn them back on.
How Bellgrid handles it
Bellgrid's settings show an "On-time class reminders" row. Tap Allow to grant "Alarms & reminders" and every class reminder rings at the exact minute you chose (5, 10, 15 or 30 minutes before). Without it, Bellgrid schedules the reminder in a short window just before that time so it does not come after class has started. Reminders are re-scheduled automatically after a restart, and you can set break dates to pause them during holidays.
FAQ
Why did my reminder come after class started?
Android groups non-exact alarms to save battery, so they can arrive minutes late. Allow “Alarms & reminders” for the app so it can schedule exact alarms.
Do I need to turn off battery optimization?
Usually no. Exact alarm permission is enough for most phones. Some manufacturers add their own app sleeping lists; take the app out of those if reminders still slip.
The reminder came but made no sound.
Check Do Not Disturb, the app's notification channel settings and whether the notification channel sound is on.