An electric car's charging time is the energy to put back into the battery divided by the power the car actually accepts. Allow a night on a home charger, a few hours on an 11 kW unit, and 18 to 45 minutes from 10 to 80% on a rapid charger, depending on the model.
How do you calculate an electric car's charging time?
One division is enough. Take the energy to put back, in kWh, add roughly 10% of losses when you charge on alternating current, then divide by the power actually accepted, in kW. If the difference between the two units still escapes you, our article on kW vs kWh sorts it out in two minutes.
The trap lies in "actually accepted". Your car contains an onboard charger, a converter that turns the grid's alternating current into direct current for the battery, and that is what sets the ceiling at home. The charge point may display 22 kW: if the onboard charger stops at 11 kW, you will charge at 11 kW, and at 6.6 kW on a standard Renault Twingo E-Tech. The figure that applies is always the lower of the two.
A concrete example, on a 48 kWh Hyundai Kona Electric. Going from 10 to 80% takes 33.6 kWh, so about 37 kWh drawn from the grid. On an 11 kW charger, that makes 3h22.
This calculation applies to alternating current. On a rapid charger, the car receives direct current that bypasses the onboard charger, and the battery's charging curve is in command.
How long does it take to charge an electric car at home?
It all depends on the socket, and the gap runs from one to five. I ran the formula on five cars sold in Belgium, for a 10 to 80% charge, the one people really do day to day, on the three most common installations here.
| Car | Battery | Onboard charger | 2.3 kW socket | 3.7 kW charger | 11 kW charger |
|---|---|---|---|---|---|
| Renault Twingo E-Tech | 27.5 kWh | 6.6 kW | 9h12 | 5h43 | 3h12 (capped at 6.6 kW) |
| Hyundai Kona Electric 48 kWh | 48 kWh | 11 kW | 16h04 | 9h59 | 3h22 |
| Tesla Model Y Rear-Wheel Drive | 69.9 kWh | 11 kW | 23h24 | 14h33 | 4h54 |
| Kia EV3 81.4 kWh | 81.4 kWh | 11 kW | 27h15 | 16h56 | 5h42 |
| Hyundai IONIQ 5 84 kWh | 84 kWh | 11 kW | 28h07 | 17h29 | 5h53 |
Our own calculation of 11 October 2026: 70% of capacity, 10% of losses on alternating current. Capacities and chargers from manufacturer data sheets; the Model Y capacity is recalculated, as Tesla does not publish it.
The formula holds up against official figures. Renault quotes 4h15 from 10 to 100% for the Twingo on its 6.6 kW charger, and the calculation gives 4h08. Kia publishes 7h15 from 10 to 100% for the EV3 on 11 kW, against 7h20 calculated. For the IONIQ 5, Hyundai quotes 7h35 from 0 to 100% on 11 kW, slightly better than our estimate, which therefore stays on the cautious side.
The right-hand column is misleading if read on its own.
Why doesn't a 22 kW charger charge any faster?
Because almost no car can use it. The 11 kW three-phase onboard charger has become the norm: it draws 16 A on each of the three phases of a 400 V connection. A 22 kW charger plugged into that car will give it 11 kW, not one more.
A few exceptions exist, nearly always as options, such as the 22 kW charger offered on the Renault Mégane and Scénic E-Tech or on the BMW iX3 Neue Klasse. The other way round, the standard Twingo stops at 6.6 kW single-phase, and a three-phase wallbox brings it nothing.
And on an ordinary domestic socket?
It is the fallback, and it covers a night for a small battery. A mode 2 cable plugged into an ordinary socket charges at about 2.3 kW, that is 10 A at 230 V. At 17 kWh per 100 km, that returns about 12 km of range per hour of charging. A reinforced socket climbs to 3.2 kW and about 17 km per hour. On the Twingo, an ordinary socket puts back 70% of the battery in just over nine hours; on an EV3, it would take more than a full day.
And on the motorway, how many minutes on a rapid charger?
From 18 to 45 minutes from 10 to 80% on a powerful unit, depending on the model. Hyundai quotes 18 minutes for the IONIQ 5 and 41 minutes for the Kona Electric, Renault 30 minutes for the Twingo fitted with the €500 Advanced Charge pack, and Kia 31 minutes for the EV3 on a 350 kW charger. Tesla publishes no official 10 to 80% time for the Model Y Rear-Wheel Drive.
The figure that interests me most is the one Kia publishes for the same EV3 on a 50 kW charger: 79 minutes. A good share of the rapid chargers installed in Belgium before 2022 still top out at that level, and on the E411 motorway on a Sunday evening, the difference is measured in cold coffee. The second half of the problem is the curve: on the EV3, power holds above 120 kW up to 70% charge, then drops towards 50 kW at 80%. Pushing to 100% on a rapid charger loses more time than a second stop. In winter, start battery preconditioning before you reach the charger, otherwise a cold battery will refuse part of the power.
The Brussels case: 11 kW advertised, 6.4 kW received
In Brussels, many houses are still connected on 3×230 V without a neutral. On that network, a three-phase charger sold as 11 kW delivers only 6.4, as our guide to the network without neutral explains. For a Model Y, the 10 to 80% charge then goes from about 4h54 to more than 8 hours, which still fits inside a night. The standard Belgian 40 A single-phase connection represents 9.2 kVA according to Energuide, and any change to the connection or the fuse box goes through a certified electrician, followed by an inspection of the installation by an approved body.
Which installation for which use?
Start from your kilometres, not from the charger's power. The table assumes a car using 17 kWh per 100 km, losses included.
| Your use | Energy to put back | Time on 2.3 kW | Time on 3.7 kW | What to do |
|---|---|---|---|---|
| 40 km a day in town | 7.5 kWh | 3h15 | 2h01 | The ordinary socket is enough, the charger is a comfort |
| Brussels to Namur round trip, 130 km | 24.3 kWh | 10h34 | 6h34 | A 3.7 kW single-phase charger fits inside the night |
| 200 km a day, high mileage | 37.4 kWh | 16h16 | 10h06 | A 7.4 kW or 11 kW charger, depending on the connection |
| Leaving on holiday, battery at 100% | Whole battery | 13 to 40 hours depending on battery | 8 to 25 hours depending on battery | Charge the day before on 11 kW, then one rapid stop |
In Flanders, moving from 3.7 to 11 kW has a price. Network charges there follow the monthly power peak, and 7.3 kW of extra peak costs 380 to 440 € a year, at 52 to 60 € per kW. If your use fits the second row, the small charger is also the cheapest. On the price per kWh, by contrast, speed changes nothing: the CREG ceilings (CREG is the Belgian federal energy regulator) for the third quarter of 2026 remain 32.22 c€ in Flanders, 35.68 c€ in Brussels and 37.83 c€ in Wallonia, whatever the charger.
Five mistakes that make charging longer
- Paying for a 22 kW charger for a car whose onboard charger stops at 11 kW, or at 6.6 kW.
- Reading the power shown on a rapid charger as a promise: the car accepts its own, and the lower one wins.
- Charging to 100% on a rapid charger, when power collapses after 80%.
- Arriving at the charger in winter with a cold battery, without preconditioning.
- Forgetting to check your connection in Brussels before buying a three-phase charger.
Frequently asked questions
How long does it take to charge an electric car from 0 to 100%?
On an 11 kW charger, allow from 4h15 (Renault Twingo E-Tech, 10 to 100%, on its 6.6 kW charger) to 7h35 (Hyundai IONIQ 5 84 kWh, 0 to 100%), according to manufacturer figures. On a domestic socket, multiply by four or five. The last 20% take proportionally longer than the rest.
How do I calculate charging time myself?
Multiply battery capacity by the percentage to put back, add 10% for losses, then divide by the lower of the two powers, charge point or onboard charger. For 70% of a 48 kWh battery on an 11 kW charger: 33.6 kWh, 37 kWh with losses, so 3h22.
What is the charging time on a 22 kW charger?
The same as on 11 kW for most cars, because their onboard charger caps alternating current at 11 kW. Only a few versions accept 22 kW, often as an option, such as the Renault Mégane and Scénic E-Tech or the BMW iX3 Neue Klasse. Check the data sheet before paying for a 22 kW charger.
Does cold weather lengthen charging time?
Yes, especially on rapid chargers. A cold battery accepts less power to protect itself, and the charging curve suffers from the first few percent. Preconditioning, which warms the battery before you reach the charger, is the fix: start it from the built-in navigation before every rapid stop in winter.
Why does charging slow down after 80%?
Because the car deliberately reduces power to protect the cells as the battery fills up. On the Kia EV3, the curve holds above 120 kW up to 70% then drops towards 50 kW at 80%. On the motorway, leaving at 70 or 80% almost always saves time.
How much charging time to recover 100 km?
For a car using 17 kWh per 100 km, about 8 hours on a 2.3 kW socket, 5 hours on a 3.7 kW charger and 1h40 on an 11 kW charger. On a rapid charger, an IONIQ 5 recovers far more in ten minutes. A more frugal car, such as the Twingo at 13.5 kWh, goes faster still.
Le verdict de Christophe F.
Before looking at the charger, look at your car's onboard charger and your daily kilometres. For most Belgian families, a 3.7 kW charger puts back overnight what was driven during the day, and the 11 kW charger only matters for big batteries and high-mileage drivers. On the road, the charging curve and the charger's power decide: aim for 80%, not 100%. The model sheets give the onboard charger of every version sold here, and the rapid-charging ranking sorts cars by their direct-current speed.
