diff --git a/preparation.md b/preparation.md
index a5db71c..35deab0 100644
--- a/preparation.md
+++ b/preparation.md
@@ -4,10 +4,22 @@ Time. It's all about time here.
 Since the only common variable among all datasources is time, the tool can only work as precise as all the clocks are set during your photosession / trip. This includes timezones as `GPX` saves times in `UTC` along with the local timezone.
 
 ## Camera
-Unless your camera has one of these shiny, integrated GPS receivers, you probably can't setup anything else from time. I always tend to live by the local timezone for obvious reasons, and so does the time on my devices. So `rad-tag.py` also assumes that timezone unaware devices use localtz.
+Unless your camera has one of these shiny, integrated GPS receivers, you probably can't setup anything else from time.
+
+I always tend to live by the local timezone for obvious reasons, and so does the time on my devices. `rad-tag.py` also assumes that timezone unaware devices use `localtz`.
 Good thing is, that the clock of the most consumer / prosumer devices does not drift too bad. Actually, in the past I set the time only once or twice per vacation.
 
 ## Mobile Phone
+Mobile phones are unproblematic regarding time. They usually already sync theirselves via NTP oder the carrier network and usually get their timezone right.
 
+Energy Saving options for apps might become a problem eventually, if your OS decides to send it into sleep mode. So you might want to define an exception:
+
+Android:
+![App energy saving][android_app_engerysave] ![Disable energy saving][android_app_exception]
+
+[android_app_engerysave]: wiki/images/android_app_energysave.png
+[android_app_exception]: wiki/images/android_app_exception.png
+
+### GPSLogger
 
 ## Geigercounter