I have a Xiaomi Redmi Note 4 S625 global variant (4/64GB).
Like a day or so ago, I noticed a quick battery drain (from 100 to 24% after a whole night idle and 2 - 3 hours of heavy use the next day) and from there it was dropping a percent every 2nd-3rd minute. It never happened before as its a 4000mAh battery and usually lasts around 2 days on normal use. I'm new to the smartphone world and I was reading online about the usual causes of battery drain including background apps consuming it and overcharging issue damaging the battery. I got worried as last night it was indeed left plugged in for like 2 - 3 hours maybe after a full charge. So either the battery is damaged due to overcharging, or its some software issue. Now what I noticed is the CPU usage is maxed with no app running in the background. I don't know if CPU-Z's usage info is accurate, but it's 100% when battery is like 15 or lower and 40-50% when battery is 20 or above. Maybe there's some background process or maybe its normal, I don't know. I'm pretty clueless at this point.
Here's a screenshot of CPU-Z: http://i.imgur.com/ZL2ipZm.png
Really appreciate if anyone helped me on this one. Thanks.