I charge to 100%, use it (to 60% by example) then shutdown and boot up... Once booted up i see that meter shows 20% or 30%.
So i follow this steps to fix it (when tablet is on dont use it):
1) Charge battery to 100% with tablet on
2) Once 100%, shutdown it, disconnect ac and reconnect it. Wait until blue led doesnt flash.
3) Once done, boot in cwm, in advanced, use delete battery stats
4) Once done, boot the tablet and leave the battery drain until it shutdown (i use setcpu and in the info label use stresstest with cpu at 1.4G with wifi and bt on. It last 4 hours)
5) Once done, put ac charger again, boot the tablet and fill your batt to 100%.
I did it and now is working ok.