I've i9195 with stock battery and rom, all was normal. Then I replaced it with double sized battery+new back cover. Not a microUSB batterycase. After many cycles and weeks of use it still didn't calibrated to new capacity. Fully charged battery lasts about a day and phone shuts down. If I switch it back ON after couple of minutes - I see 50% charged and can use phone another day.After second 'full discharge' I'll have about 15% more. All techniques for 'calibrating' battery with deleting batterystats doesn't work. Charge, off, remove bat, wait, place it back - either. /sys/class/power_supply/battery/uevent have string POWER_SUPPLY_ENERGY_FULL=1940000000 and it is always the same. So phone simply downcount from this level and tells that charge is 0% while voltage is about 3.7v. Interesting that "energy_full" file has number of 3880000000 but it seems that it's not used in calculations.
After all I installed CWM, root, cyanogenmod 11 and used it for about a week. SAME problems, except that "energy_full" is 1940000000.
I want to solve this very much, I can program or recompile kernel, if needed. It's pm8921 charger ic there. Maybe this number was programmed in it in factory mode or smth. Maybe threis a way to correct it. Thanks in advance.