Default L7 II Battery drain

Hello.
I want to know if there's someone else having this issue.
I charge my phone (p712) to 100%, and when I restart it/shut it down and start it without being pluged to charger wire it starts at 94% and it goes to 89% in less than a minute, after that it get slowing down a little but still goes down quickly till 50% and then it takes longer to decrease the %.
I already calibrated the battery.
┐Maybe it's a rom problem? ┐or it's not optimized for battery visualization?
Thanks for comments.