ToolnozaCharging time formula
Energy added to the battery = usable capacity × (target state of charge − starting state of charge) ÷ 100. Approximate time in hours = energy added ÷ (charger power × charging efficiency). Use kWh and kW so the result is in hours.
Example: a 60 kWh battery on a 7.2 kW charger
Charging from 20% to 80% adds 60 × 0.60 = 36 kWh to the battery. At 90% efficiency, approximate time is 36 ÷ (7.2 × 0.90) = 5.56 hours. This is a simplified estimate, not a promised charging session duration.
Why actual charging can take longer
The car may accept less power than the charger can provide. Temperature, battery conditioning, shared circuits and tapering at high charge levels affect the rate. Public DC charging often slows as the battery approaches full; a constant-power formula does not model that curve.
Frequently asked questions
Should I use charger or vehicle power? Use the lower power limit. Does the calculator include charging losses? Enter an efficiency estimate if the tool supports it. Can I assume full power to 100%? Usually not; charging commonly slows at higher states of charge.