mobile

I have a new Samsung S4. Trying to learn how best to configure it to minimise battery usage and to ensure I don't install apps that eat battery. There's nothing wrong with it, battery usage is fine, just trying to get the best out of it; whilst keeping as much functionality as possible without having to constantly turn things on and off. I'm trying to avoid rooting it.

As a starting point, I'm checking usage overnight, when blocking mode and power saving are on, with wi-fi and data off; but with the alarm clock set.

I have an i-onik 7.85" tablet on Android 4.2.2 - with a deep sleep battery saver app set to slumberer ("always deep sleep when screen off") it only uses about 2% of battery overnight - the battery currently holds about 3600 mAh - so that 3% equates to 108mAh.

First time I tested my Samsung S4 (the european LTE version 9505), (actually I think I had wifi, data, location setting turned on and power saving turned off), it used 4% battery overnight. Not bad, 4% of 2600 mAh is 104 mAh. Still I thought I might do better. I tried the deep sleep app on slumberer but inexplicably the usage then jumped to 12% (whereas it at least halves battery usage on my tablet). I've since un-installed deep sleep battery saver and started turning off wi-fi, data, and turning on power saving - so I'd expect it to use 4% or less battery overnight.

The actual battery usage instead increased to around 9% to 12% - although the settings used might have varied.

Three nights ago I made sure that all apps were closed, and everything turned off as above - battery usage overnight was still 9%. I used WakeLock Detector and found that a Morrisons App was causing wakelocks. I uninstalled that, and the next night the battery usages was down to 6% with much fewer wakelocks. Still not as good as before though.

I then found there were wakelocks due hotmail and gmail sync - hotmail I changed from push sync to sync every 4 hours, gmail I changed from hourly sync to manual sync and I also turned off master sync. I also turned off location setting. That cleared the wakelocks for these apps, but battery usage last night had increased to 9%.

So, despite the same settings and less wakelocks (and it was in deep sleep all night except for 16 minutes), battery usage increased from 6% to 9% - still no where near the 4% I had at the start despite making various changes that should reduce battery consumption.

The only significant wakelocks last night were:

com.domobile.applock (via alarmManager) awake 35s giving 992 cpu wakelocks
com.google.android.google (google app) 7 wakeups

Can anyone think of any cause for increased battery usage from 6% to 9% despite more time in deepsleep, less wakelocks (other than the 2 above but there were many more wakelocks the night before lasting several minutes) and location setting turned off. I wonder about starting again from a factory reset ... NB every night before going to bed I've rebooted the phone, and charged it to between 90% and 96% and it's been tested over the same period of time. Is it normal for battery usage when the phone is sleeping to vary so much?