Quick power loss after upgrade

[Old1chun]

After upgrade the sony recommend os, a "N" word-like icon shown near my clock on the top notificaton bar.

And battery power has great loss(imagine almost 2 min drop 1%)

But I cannot find out the power loss source (all app show few % of total consumption). 

And I cannot find out the suspective app name or new app in application page.....

After I upgrade again without factory restore (sony recommend also).

What I can do?

[Capitaine_Hardo]

The N icon means that NFC (wireless transfer protocol, via close contact between two peripherals) is activated. That may reduce your battery life. You can deactivate it in the parameters