Well, after looking at this issue I think I have come up with solution.
At least, my tab looks like it's back on track... though, to say for sure I would need another couple days of testing.
The problem is not runaway wild application on a background but battery control circuit. This chip reports to OS much smaller battery capacity as it is for some reason. I will not go into details but here is what you need to try:
Flash stock kernel (may be custom kernel is not the reason for bad chip calibration and I'm 90% positive but just to be on safe side). You don't need to do factory wipe in OEM recovery for our purpose.
You also don't need to wipe batterystats.bin or use "Battery Calibration" apps from market (which does exactly the same wipe just in more end user friendly way). This wipe serves no other purpose then refreshing your usage statistics.
You also don't need to drain your battery all way down... nice, this way you don't have to wait for too long.
Well, here we go:
charge tab somewhere in between 80 and 100%.
edit: remove charger
shutdown tab (not put in hibernate/sleep) for 1 hour.
edit: turn tab on and run it for 30-40 min. or whatever it takes to drop charge to 40-50%.
shutdown tab again for 5 hours (overnight).
turn tab again and check... you should be fine now, charge it again 100% and use as usual.
That should do correct chip calibration.
PS: the reason why this chip calibration went bad at the first still remains open.
EDIT: just want to give a shortcut for those who does not feel like reading through the thread.
Edit: here is calibration procedure which was modified down this thread ...
1. in CWM/recovery let it sit till battery in terminal will show less then 3700. The less you can get it the better. 3400 is probably absolute minimum.
2. shut down tab and let it sit for 1 hour.
3. plug it to charger and charge it for 5 hours.
4. disconnected charger and let it sit for 1 hour.
5. boot up your tab and test it, it your battery still not calibrated you can flash back your backup and repeat calibration procedure.
Edit: if you physically disconnect battery (you have to disassemble tablet) and keep it for couple min. that would trigger FG chip to start with default SOC curve.