May not fit topic EXACTLY but...i've run die hard battery calibrator script (credit to zeppelinriox), takes a longgggg time to reach the full voltage, but that script makes a huge huge difference at least it did for my phone, showing current charge vs actual charge, and forcing charge untill full 4200mv = reached, then pushed until batteries true max. (therefore maybe this script can be integrated into roms, and regardless of your battery mAh status, it should calibrate it perfectly)
original link:
xda-developers - View Single Post - [U9RC11T6] Maximum MultiTasking Mods + -=V6 SuperCharger=- = TOTAL RAM CONTROL!
Die Hard Battery Calibrator Listed @ Bottom Under Downloads.