How to calculate electric car charging time
Charging time depends on the energy you need and the power the car can actually maintain. Start with the exact version, then distinguish a simple AC estimate from a DC charging curve.
Use the usable battery capacity, rather than the gross or nominal figure. Multiply it by the change in state of charge expressed as a fraction. With 60 kWh usable, charging from 20% to 80% stores 60 × 0.60 = 36 kWh.
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01
Start with the energy to add
State of charge is a percentage, not an amount of energy. The same 20–80% window stores different amounts in different batteries. Check the model year and battery version before using a catalogue value. An indicative capacity remains an estimate when used in a calculation.
02
The AC formula, including losses
Time in hours ≈ energy stored ÷ charging efficiency ÷ effective power. With 36 kWh to store, 90% efficiency and a constant 7.4 kW input, the estimate is 36 ÷ 0.90 ÷ 7.4 = about 5 hours 25 minutes, rounded up.
The effective power cannot exceed the car’s onboard AC charger. A 22 kW point does not make an 11 kW car charge at 22 kW.
Supply capacity, compatible phases, other household loads and the charging device may reduce it further. If the power you use already describes energy entering the battery after losses, do not apply the same losses again.
03
Why the DC peak is not enough
In DC charging, power varies as the session progresses. Temperature, battery conditioning, state of charge, the station and power sharing can change the curve. Dividing the required energy by the peak gives an idealised constant-power result, not a reliable charging time.
For the launch Renault 5 Comfort Range 52 kWh, the documented example is 15–80% in 30 minutes with a 100 kW DC peak.
The constant-peak calculation gives 52 × 0.65 ÷ 100 × 60 = 20.28 minutes. The difference illustrates why a peak must not be treated as the average. This 15–80% reference is not a 10–80% or 20–80% claim.
Ricaora uses the available reference and its modelling assumptions. Its result is an estimate, not a measurement or a guaranteed session time.
More examples and detail
Examples from the expanded catalogue
Compare the figures
Catalogue examples: 20–80% AC, assumed 90% efficiency, constant compatible power
Škoda Epiq 40 · Italy 2026
- 3.7 kW
- 6 h 41 min
- 7.4 kW
- 3 h 20 min
- 11 kW
- 2 h 15 min
Škoda Epiq 55 Selection · Italy 2026
- 3.7 kW
- 9 h 19 min
- 7.4 kW
- 4 h 40 min
- 11 kW
- 3 h 08 min
Mercedes-Benz VLE 300 Electric · Italy 2026
- 3.7 kW
- 20 h 44 min
- 7.4 kW
- 10 h 22 min
- 11 kW
- 6 h 59 min
Comparison from the table in this guide.
| Version | 3.7 kW | 7.4 kW | 11 kW |
|---|---|---|---|
| Škoda Epiq 40 · Italy 2026 | 6 h 41 min | 3 h 20 min | 2 h 15 min |
| Škoda Epiq 55 Selection · Italy 2026 | 9 h 19 min | 4 h 40 min | 3 h 08 min |
| Mercedes-Benz VLE 300 Electric · Italy 2026 | 20 h 44 min | 10 h 22 min | 6 h 59 min |
Rounded up to the next minute. Formula: usable capacity × 0.60 ÷ 0.90 ÷ effective power. These are illustrative AC estimates, not measurements or installation recommendations.
Specifications refer to the version, year and market shown. Model records have English notes; original source documents may use another language. They do not certify current availability in your country.
05
Sources and method
English editorial version updated 16 October 2026. Arithmetic examples are Ricaora calculations. Efficiencies, consumption assumptions and example tariffs are not measured vehicle results or current commercial offers.
Installation requirements and electricity contracts vary by country; use qualified local advice for the electrical system.