is this battery drainage normal on NL820?

[ideocard]

I've had several various android phones over the years, and Lumia 820 is my first WP phone. I've had it for months now and it was satisfying at first 2 months.

In order to increasing the battery life, I switched off the bulk of items like WiFi, Gps, etc and used them only needed, it worked, but recently I have suffered really fast drain on my battery even in battery saving mode--- lasts 7-9 hrs from almost 100% to 0% with moderate use. If I unplugged it moring, 3 hrs later almost half of the battery is drained, this is unacceptable!

Not sure the exact reason. Can this problem be solved if pop in a fresh one?? I already ordered a new secondary one from MPJ. Anyone have similar exp.?? Is this a normal drainmage after several months usage or my stock battery just going to died??

[cyan]

I think this is a WP Phone bug n not sure about the reason also, I personally switch a new one and the world change since then