I'm gonna try calibrating that thing one more time. From full charged state, drained the battery continuiously (no shutdown/restart), when it goes to sleep I'm gonna wake it up to shut it down through the OS, then plug in the power adapter and wait for it to be full charged (until green light). The last time I just hold the power button when it got to sleep, I realized that it didnt actually shutdown but just went into a powerless sleep (data saved to hard drive, power off).
I hate to contact AppleCare for replacement, I really prefer my hardwares to be as original as possible.