If you think that your battery just drains too fast or if it jumps from 100% to 93% right after pulling the charging cable, this trick here seems to do wonders:
Follow these steps:
-Turn the phone on and plug it in
-When the light turns green (if it is completely charged), disconnect the phone from the charger and power it off
-When it is completely off, plug the phone in the charger again
-Wait until the light turns green again (indicating that it is completely charged)
-Disconnect the phone from the charger, power it on (wait until it is completely on) and power it off again
-When it is completely off, plug it in the charger and wait for the light to turn green again.
We are finished! Unplug the phone and use it. IF you use a recovery menu, try to wipe the battery stats (found in the advanced submenu).