spike in battery charge Today when I was charging my Redmi 1s mobile I restarted the mobile. Then I saw that there was a sudden increase in the charge of the battery by 80%.
What could have caused this?
Smartphones have a particular text file in which is contained the drain value... 
If you delete this file the device recreates it when it boots and the battery percentage may display a 50% to 70% difference. 
Chances are you use to charge your phone everytime you want without completing a full cycle of recharge once a month (at least). 
This way the phone displays a percentage that is different from the real one... 
So when you rebooted your phone it automatically (and somehow) deleted this file and then recreated it again with the right drain value and battery percentage...