For some users the battery may drop all of a sudden from 34% to 12% while for some it may be different. For me it was always 34% - 12%.
Now the one important thing that I observed was that when I used to charge my mobile , the charging jumped straight from 76% to 100% . In my view the battery was never charged for the last 20%. And it was this 20% that appeared as the sudden drop.
Now coming to the solution..
Battery calibration and wiping batterystats.bin actually never solved the problem because I tried both.I don't know if changing the Kernel did.
So I have come up with one solution that won't disappoint you..
Follow the steps..
1. Let your battery drain to below 10%.. say 8% ..
2. Charge your battery like u always do..
3. When the battery reaches 100% , do not disconnect the charger, go to System settings and then battery and check the graph..(don't disconnect the charger because doing so will reset the graph).
4. notice the sudden increase in battery charging.
5. Use the phone as u always do and let it discharge to 70% ..
6.Here comes the LIFE SAVING STEP..Now what you have to do is charge your phone in one go..there should be no interruption in charging..If the electricity goes off even for a second..the whole process fails..so prefer using a UPS..
7. Let the battery charge to 100% and use normally.
8. Its my guarantee that the battery drop is gone.
The bad part..
The problem reappears after a reboot.. and we have to repeat the procedure again.