Set an alarm on the stock app at night before going to bed and the battery runs down before the alarm goes off.
Requires a restart to fix the problem even after the alarm is turned off or deactivated.
Device and system software info:
Android version 4.0.4
Kernel version 3.0.8
Troubleshooting to date:
1) Started with a device that had a battery drain issue in addition to this one. Phone was effectively a pocket warmer.
1a) Got a new battery from AT&T, no success.
1b) Factory reset, no success.
1b) Got a new device from AT&T and whatever the other issue was didn't exist on the new device. Getting 48-72 hours out of the new device provided I don't set an alarm on the clock app.
2) Set the alarm on the stock app with new device. Same issue.
3) Downloaded new alarm app. Alarm Clock Plus V.5.1.
3a) Set the alarm, same issue, battery dies overnight.
3b) Unset the alarm, recharged a bit, monitored battery usage. Device continued to eat battery at a higher than normal rate even after Task Manager RAM clear.
3c) Device required restart to clear the problem.
Battery drain stats:
Period 1-2 (3.5 hrs)
Rate: 10.0% per hour discharge
Period 2-3 (0.6 hrs)
Rate: 16.8% per hour charge
Period 3-4 (2.7 hrs)
Rate: 10.2% per hour discharge
Period 4-5 (1.8 hrs)
Use: Restart then none
Rate: 24.8% per hour charge
Period 6-7 (6.8 hrs)
Rate: 0.4% per hour discharge
Period 7-8 (14.9 hrs)
Use: Moderate to normal
Rate: 1.6% per hour discharge
As you can see from looking at the information above, with the alarm set, the discharge rate was about 10% per hour. Even after the alarm was turned off, that discharge rate continued until the device was restarted.
Comparing recharge periods, the recharge rate was about 8% per hour lower (16.7 v. 24.8) before the device was restarted even without the alarm on.
Normal dormant discharge rate was 0.4% per hour. Even with moderate to normal use (web browsing, Tapatalk, various apps, GPS), the discharge rate was 1.6% per hour.
Other points of interest:
By percentage of battery use, the task manager listed cell standby, screen and android system as the largest consumers of battery power. The screen and system usage varied across periods depending on actual use, but cell standby accounted for roughly 45% of use across all periods.
Both wifi and GPS were enabled during all periods. The device was on home wifi for all periods except the roughly 15 hours of Period 7-8. During that period it was on home wifi for roughly half that time, with wifi active during the entire period.
1) It doesn't seem that wifi or GPS are a player for the battery drain exhibited during the period the alarm was set or the period after, prior to device restart.
2) It seems like turning on the alarm puts the device in a state where it remains on even though the screen is not. Whatever it is doing during that time is sucking down power at a rate higher than actual use. The 10% per hour discharge rate with the alarm set is higher than that of any other period. It isn't even synonomous with heavy use with the display on.
3) This battery drain seems consistent with rates using the stock clock alarm app. I don't think this is an app specific problem, rather an issue with whatever gets turned on in the android system when the alarm is activated.