add offset in % for mAh and Wh values to adjust them against your real battery charger outputs.
this mean, if mAh on taranis screen display 2000mAh after your flight,but your charger told you later that 2200mAh are chareged to this battery, than you can set offset for mAh to 10% inside model offset script.
the same for WH if your charger inform you correctly about this value.

inputs are
O-Set mAh% -100 to 100 default 0
O-Set Wh% -100 to 100 default 0