EV charger power: 11 kW or 22 kW?

Typical AC charger power ratings

• 3.7 kW — single phase, 16 A. Enough for plug-in hybrids and overnight charging.
• 7.4 kW — single phase, 32 A. Popular where only a single-phase supply is available.
• 11 kW — three phases, 16 A. The standard in apartment buildings, offices and hotels; this is what most electric cars can accept.
• 22 kW — three phases, 32 A. Faster charging, but only for cars with a 22 kW on-board charger.

11 kW vs 22 kW: when the difference matters

AC charging power is limited by the car’s on-board charger. Most electric cars accept a maximum of 11 kW, and only a handful of models support 22 kW. If you plug a car with an 11 kW on-board charger into a 22 kW charger, it will still charge at 11 kW.

At a consumption of about 18 kWh per 100 km, one hour of charging adds roughly: 3.7 kW — approx. 20 km of range, 7.4 kW — approx. 40 km, 11 kW — approx. 60 km, 22 kW — approx. 120 km (only if the car can accept that power). An 11 kW charger tops up a typical daily mileage of 40–50 km in under an hour.

Indicative figures: the range added per hour of charging depends on the specific car’s energy consumption, the temperature and the battery’s condition.

What limits real charging power

• The car’s on-board charger — usually 11 kW, and in some models and hybrids single-phase only (3.7 or 7.4 kW).
• The building’s connection capacity and spare capacity in the installation — this determines how many points can charge at the same time.
• Cable cross-section and protective devices — a 22 kW charger needs a thicker cable and 32 A protection, which raises the installation cost.
• The number of cars charging at the same time — with load management, they share the available power between them.

Charger power vs building capacity

In an apartment building, what counts is not the power of a single charger but the total. Ten 22 kW chargers theoretically add up to 220 kW, and ten 11 kW chargers to 110 kW. Hardly any residential block has that much spare capacity, and increasing it with the grid operator can be expensive and time-consuming.

That is why dynamic load balancing (DLB) is key. The system shares the available power among the cars that are actually charging at a given moment: when one car is charging, it gets full power; when several are, the power is split between them without exceeding the building’s limit. Because residents charge mainly overnight, over many hours, every car still has a charged battery in the morning.

What power to choose for your site

Charger power should be matched to users’ cars, parking time and the installation’s capabilities — not to the highest number in the catalogue. Our recommendations:

• Apartment block, community garage, office: 11 kW with load management — charging while parked overnight or during the working day is more than enough.
• House or parking space with a single-phase supply: 7.4 kW.
• Hotel, commercial car park, fleet of cars with a 22 kW on-board charger: 22 kW can shorten the stop, if the connection capacity allows it.
• Future-proofing: many 22 kW chargers can be limited to 11 kW in software and unlocked later, when more power becomes available or the cars change.

Load management and billing in one system

The Domena Power system works with 11 and 22 kW AC chargers that support the OCPP protocol (the open communication standard for chargers), regardless of the manufacturer. It lets you set power limits for a site or a group of chargers, manage the load dynamically and monitor charging peaks, and it bills every session to a specific user — with no commission on energy sales.