Great piece of advice. Thx bro.  after this I will do as suggested & try one by one which is the app is hogging the battery. For a start, I will hard reset my device & see whether I can accomplish this less than 2% drain with 3G on. Subsequently, I will install one app to test the drain. Hopefully I will catch the main culprit...benny you think my action plan is feasible?

The remedy is greenify...damn then I need to root my nexus already. Any other similar like greenify that doesn't require root?

Anyone have the screen freeze issue? Sometimes my device frozen for few second then back to normal.. Found a thread on XDA:

Screen Freezes

same here. it will stuck at one letter. now it starts to annoy me.
PA hybrid feature, change it to phone mode.
watch video, play phone games(bigger screen), use it as second screen. if u got nex10, i tink no nid for another, unless u prefer portability rather than bigger screen. i bought it for portability, and a bigger screen size compared to my phone.
google pinyin. stock only english.

Android 4.4 is just around the corner, new build "KRT14B" on new Nexus 7 (2013) is spotted in Bluetooth SIG database, build date is 14 Oct.

Google please release it faster