Hey solca. I was working on a program to read retu data and estimate battery level (this was in Maemo/Hildon, not Android). It used a battery level history file to predict how much % was left. It was extremely volitile for the reasons you mention. I figured that some "smoothing" was needed to make it more accurate, but the only way to do this is to know the current battery draw, but was unable to retrieve this data from the system (it is possible though, because an application called "Field Test Display"* can read it). BTW, you can catch charging/discharging events via dbus, though I couldn't quite figure out how to do it. *=With the bme plugin.