Hi bro, from the above graph battery drain overnight looks stable. you have charged 80% and started using it. network signal strength is less and using apps or video streaming may increase battery consumption in such conditions.
Dont worry, as you roam around, it will keep on changing and let the battery reach 20% for your normal day time usage. then charge it to 80% or any level you want.
Once it reaches 20% then you can read to understand it better.
