The right choice is the lowest-cost compatible setup that reliably replaces your daily energy within your charging window—with room for the changes you realistically expect.
1. Start with the car’s AC charging limit
For AC charging, the onboard charger (OBC) inside the car converts AC electricity into DC for the battery. A wallbox or portable charging unit supplies controlled AC power; it cannot upgrade the car’s OBC. Look up the exact model year, market and installed OBC option. Check both the maximum AC power and the supported current on single-phase and three-phase supplies. A DC rapid-charging figure does not answer this question.
2. Check what your home can supply
For the typical European homes covered here, first identify whether the supply is single-phase or three-phase. At 230/400 V, 3.68 kW requires single-phase 16 A; 7.36 kW requires single-phase 32 A; 11 kW requires three-phase 16 A per phase; and 22 kW requires three-phase 32 A per phase. To charge at 11 or 22 kW, your home must have a three-phase supply with sufficient capacity. If your home has a single-phase supply, choose a charger that supports single-phase operation.
Next, confirm the permitted incoming current: ask your electrician or network operator for the rating or setting of the main circuit breaker or main service fuse, and any contracted supply limit. For a three-phase supply, a rating such as 3 × 25 A means 25 A on each phase—not 75 A available on one phase. The marking on a main switch alone does not establish your supply capacity.
The incoming cable’s safe current-carrying capacity is not automatically equal to the main breaker rating. It depends on the conductor size and material, installation method and conditions. An electrician must verify that the cable, protection and permitted supply capacity are compatible.
The whole home shares this capacity. Allow for cooking, heating, hot water and other simultaneous loads, on each phase where applicable. For example, a three-phase 25 A supply cannot provide 32 A per phase for 22 kW charging; even 11 kW at 16 A per phase requires enough headroom for the home. Dynamic load balancing can reduce charging current as household demand rises. Have the dedicated charging circuit, protection and local connection requirements checked before choosing the charger; compare the total installed cost.
3. Read the vehicle × charger matrix
This matrix describes four OBC configurations, not four universal vehicle categories. It assumes a compatible Type 2 connection, a typical European 230/400 V supply, the stated number of phases and full configured current. Read the row that matches your car, then the column for the charger you are considering.
Select your EV configuration to highlight the lowest charger rating in this table that reaches its AC limit.
| EV AC Charging Capability (OBC) | 3.68 kW Charger* 16 A · 1-phase | 7.36 kW Charger 32 A · 1-phase | 11 kW Charger 16 A · 3-phase | 22 kW Charger 32 A · 3-phase |
|---|---|---|---|---|
| 7.36 kW OBC · single-phase 32 A | ≈ 3.68 kW16 A · 1-phase | ≈ 7.36 kW32 A · 1-phase | ≈ 3.68 kW16 A · 1-phase | ≈ 7.36 kW32 A · 1-phase |
| 11 kW OBC · three-phase 16 A; single-phase limited to 16 A | ≈ 3.68 kW16 A · 1-phase | ≈ 3.68 kW16 A · 1-phase | ≈ 11 kW16 A · 3-phase | ≈ 11 kW16 A · 3-phase |
| 11 kW OBC · three-phase 16 A; single-phase supports 32 A | ≈ 3.68 kW16 A · 1-phase | ≈ 7.36 kW32 A · 1-phase | ≈ 11 kW16 A · 3-phase | ≈ 11 kW16 A · 3-phase |
| 22 kW OBC · three-phase 32 A; single-phase supports 32 A | ≈ 3.68 kW16 A · 1-phase | ≈ 7.36 kW32 A · 1-phase | ≈ 11 kW16 A · 3-phase | ≈ 22 kW32 A · 3-phase |
* Household sockets: Reduce charging current and power to comply with local regulations and the socket and circuit’s continuous-current limits, helping prevent overheating. Not every household socket is suitable for 16 A / 3.68 kW charging.
Nominal figures: 230 V × 16 A ≈ 3.68 kW; 230 V × 32 A ≈ 7.36 kW; three phases × 230 V × 16/32 A ≈ 11/22 kW. “3.5 kW” and “7 kW” are common rounded labels. These are AC input estimates, not power guaranteed into the battery. Voltage, cable limits, vehicle settings, battery conditions and household demand can lower the result.
4. Why a bigger number may not charge faster
A single-phase 32 A car connected to an 11 kW three-phase charger normally uses only one of its 16 A phases: about 3.68 kW. The three phases do not combine into 48 A on one phase. Conversely, an 11 kW car on a 22 kW charger still has an 11 kW AC ceiling. Some 11 kW cars accept only 16 A on single phase; others accept 32 A. Do not infer the single-phase limit from the 11 kW badge alone. The last row also assumes that the 22 kW OBC accepts 32 A on a single phase.
5. Size the charger for your daily driving
Start with energy to replace each day rather than the full battery capacity. Example: 60 km/day × 18 kWh/100 km = 10.8 kWh into the battery. If you assume 90% charging efficiency for planning, that is about 12 kWh from the supply. With eight hours available, the required average input is only 1.5 kW. Efficiency varies, so allow margin for winter, longer trips and shorter off-peak windows. The times below are illustrative, not a vehicle-specific promise.
| Usable AC power | 10 kWh | 20 kWh | 40 kWh | 60 kWh | 80 kWh | 100 kWh |
|---|---|---|---|---|---|---|
| 3.68 kW | 2 h 43 min | 5 h 26 min | 10 h 52 min | 16 h 18 min | 21 h 44 min | 27 h 10 min |
| 7.36 kW | 1 h 22 min | 2 h 43 min | 5 h 26 min | 8 h 9 min | 10 h 52 min | 13 h 35 min |
| 11 kW | 55 min | 1 h 49 min | 3 h 38 min | 5 h 27 min | 7 h 16 min | 9 h 5 min |
| 22 kW | 27 min | 55 min | 1 h 49 min | 2 h 44 min | 3 h 38 min | 4 h 33 min |
Time = AC energy supplied ÷ usable AC power, rounded to the nearest minute. Assumes constant power. These kWh values are energy drawn from the supply, not battery capacity or energy stored in the battery; charging losses and changing power affect actual time.
6. Decide which power level makes sense
7–7.36 kW is a useful option where single-phase supply and the car both support 32 A. An 11 kW setup is often a good match for a three-phase 16 A OBC and overnight charging. Consider 22 kW when the car can actually use 22 kW AC, the installation supports 32 A per phase and a shorter charging window matters. It can also provide future flexibility, but only if the extra equipment and installation cost is justified. A higher-rated unit may be configured lower when the manufacturer and installation permit it.
7. Choose the charger format and useful features
A wallbox is convenient for regular home charging; a portable unit offers flexibility at suitable, correctly rated outlets. Match the vehicle connector, cable rating, cable length and parking position. Choose tethered cable or a socket according to your routine. Scheduling helps use cheaper hours; dynamic load balancing shares available capacity with the home; solar charging can use surplus generation. Check which meter, connectivity, activation or subscription each feature requires. These features manage charging; they do not raise the car’s AC limit.
8. Your checklist before buying
Confirm the exact AC OBC specification, including single-phase current. Get the installation assessed and quoted. Estimate your normal daily energy and available charging hours. Check connector, cable and outlet compatibility. Compare total installed cost, warranty and support. Only then choose the power rating and smart features. This guide covers typical European AC arrangements; North American split-phase ratings and other supply systems need their own vehicle and installation specifications.