Methodology: battery energy required = usable battery capacity × change in state of charge. Effective charging power is the lower of charger output and vehicle charging limit. Grid energy is estimated by dividing battery energy added by charging efficiency. For AC charging, charging power is treated as approximately constant. For DC fast charging, charging above 80% is estimated separately using the entered high-SOC power factor because vehicles normally reduce charging power at high battery state of charge. This is an estimate rather than a vehicle-specific charging curve.