How to use this calculator
Use usable battery capacity, not necessarily the advertised gross capacity. Power should be average input power from the charger, not battery-side power.
Real charging time depends on taper, temperature, conditioning and shared power. The estimate excludes session fees, idle fees and time-based charges.
The formula
Battery energy = capacity × (target − start) ÷ 100. Grid energy = battery energy ÷ (efficiency ÷ 100). Time = grid energy ÷ average input power.
A worked example
A 60 kWh battery charging from 20% to 80% stores 36 kWh. At 90% efficiency it draws 40 kWh, costs 10 at 0.25/kWh and takes about 5.56 hours at 7.2 kW.
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