The 3080mah battery in the MiA1 lasted for roughly 15 hours with heavy usage. We had Outlook, Facebook, Youtube, Twitter, Telegram, Gmail and Whatsapp running in the background at all time.
In my Hd video loop, the MiA1 managed to run for 10 hours and 18 minutes. which was decent but not great.
One of the problems that the mia1 will face is that other xiaomi devices have better battery performance.
The company has stated that the mia1 will be shipping with a bulky charger keeping in mind the patchy elecricity situation in india, which seems like a gimmick to us.