I have noticed this since the past few days, battery drops from like 70 to 40 within less than half hour of use(casual usage). It has been about 7 months since I bought this phone. Does anyone else experience this?
Hi @Nullmegh, sorry to hear about this. 
Do you remember if you installed a new application or a new system update in the past few days?
A good place to start is to use your device in safe mode for an hour or so and see if you experience the same behaviour or not. In safe mode downloaded applications aren't loaded, so we can see if any of them are the cause of the high battery usage.
If you haven't restarted your device in a while, this is also a good thing to do, just to make sure that everything is closed down, in case something is stuck in the background and is using battery, when it shouldn't do so.
Let me know how it goes! 
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