Battery woes

I was on a visit to Mumbai for a week and the place I stayed had a bad network coverage. I knew that the battery would suffer in those conditions but it turned out to be worse. It was draining around 20% per hour, just sitting idle. I had this app called Insider that plots a nice battery stats and I used to check it frequently. The curve was very steep during those days and I thought I will disable the data connection for a while. Now, the Insider seems buggy that it won't plot while the data connection is off. In the picture, the battery is at 24% and the plot is stuck at 30 when I disabled the data. And it complains that the background task has been turned off. Weird.