Hi, I had been playing around with my Lumia 640 XL and found out something that may be useful for most of us. I do a lot of hard resets to my phone, not because of any problem (most times) but because I like it running as Microsoft wanted it from the very beginning (hahaha joke, it's just that I like it to run smoothly. Going back to the tip: having seen the difference between the battery drain when having most apps blocked not to run in the background I saw draining of about 2-4% at night with average user usage (social networks, videos, games). So I decided one day not to block any (just had done the hard reset) and saw the battery lasted more having the same usage with differences of about 1-2% at night. Try it... May save some energy and consequently savings on your bills. 
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