What Is a 40 kW DC Charging Station, Who Is It For and How Fast Is It?

Someone searching for a "40 kW DC charging station" usually wants to know two things: how quickly does this station fill a car, and is it right for my business (a shopping centre, hotel, supermarket, office building or small vehicle fleet)? In this guide we explain in plain language why DC fast charging is faster than AC, what 40 kW really means with a worked example, which locations it suits and where the 40 kW option sits in the Bemis BEVDC series. Instead of promising exact minutes and prices, we focus on the real technical facts that will put your decision on the right footing.

What is DC fast charging and why is it faster than AC?

The easiest way to understand the difference is to look at "where the electricity is converted". The electricity coming from the grid is alternating current (AC), while the battery is filled with direct current (DC). In AC charging this AC→DC conversion is done by the converter inside the vehicle (the onboard charger), and that unit is usually limited to 7.4-22 kW — so however powerful the station is, the car's own unit sets the ceiling. In DC charging the conversion is done INSIDE the station and DC is fed straight to the battery. The limit of the onboard unit is thus taken out of the equation; charging at much higher power, and much faster, becomes possible. That is exactly why "fast charging" is possible.

• AC charging: the conversion is done in the vehicle; the speed is limited by the converter inside the car (mostly 7.4-22 kW).
• DC charging: the conversion is done inside the station; DC is fed straight to the battery and the ceiling of the onboard unit is bypassed.
• The result: a DC station transfers far more energy in the same time — which is why it is called "fast charging".
• In Türkiye the standard connector for public DC charging is CCS2.

How fast is a 40 kW DC charging station?

For a rough estimate there is a simple formula: time ≈ energy to be added to the battery (kWh) ÷ charging power (kW). An example (hypothetical): suppose you want to add 40 kWh to your battery. On a car that accepts the full 40 kW this theoretically takes about 1 hour (40 ÷ 40 = 1). Taking the same 40 kWh at 22 kW AC comes to about 2 hours; and since the converter inside many cars accepts 11 rather than 22 kW, the time on AC can stretch even further. The real time depends on the power the car accepts at that moment and on the battery deliberately slowing down (especially past 80%), that is, on taper. That is why a firm promise of "full in X minutes" is not realistic — the formula only gives you the right order of magnitude.

Who is 40 kW DC for? Where is it used?

40 kW is a cost-effective entry point into the DC world: distinctly faster than AC, but at a more suitable scale than the very high-power units found on motorways. It is tailor-made for medium-intensity locations where a customer or an employee parks the car and gets a worthwhile amount of charge while going about something else (shopping, a meal, a meeting, an overnight stay).

• Shopping centres and supermarkets: the car charges while the customer shops.
• Hotels, office buildings and restaurants: the length of a stay or a visit allows enough time for charging.
• Business and office car parks: a practical speed for staff and visitor vehicles.
• Small vehicle fleets: top-ups during the day keep the vehicle out in the field.

By contrast, at motorway service areas, at locations with very high vehicle turnover or where the expectation is "fill it in the shortest possible time without a break", 40 kW may fall short; at such places higher-power DC units in the 80-200 kW range are preferred. The right power is chosen less by the brand of the device than by the traffic of the location and the waiting time that is acceptable there.

AC 22 kW, DC 40 kW or DC 80-120 kW? A decision table

The key question when reading the table is this: how long does the person parking the car stay there? If the stay is long and the aim is "let it fill overnight", AC 22 kW is enough. If the stay is a few hours (shopping, a meal, an overnight stay) and you want to offer the customer a concrete amount of charge, 40 kW DC fills exactly that gap. If the stay is very short and the aim is "back on the road as fast as possible", 80 kW and above is needed. That is why many businesses prefer to start with 40 kW DC before enlarging the investment and to scale up as they see real demand.

The Bemis BEVDC series: 40, 80, 120, 160 and 200 kW

Bemis's DC fast-charging family is the BEVDC series, offering options from 40 kW up to 200 kW. The whole series has CCS2 connectors, is compatible with the OCPP 1.6J / 2.0.1 protocols (remote management, user authorisation and reporting), takes an AC 380-480 V three-phase input, delivers a 150-1000 V DC output and has an enclosure protected for outdoor use. The BEVDC 40, the 40 kW entry point, has a single socket; that is, it charges one car at a time and is ideal for single-point scenarios.

The single-socket BEVDC 40 is the way to move up to DC speed with a low entry cost, for small businesses and single-point installations. As the need grows — more cars, higher circulation — the dual-socket models of 80 kW and above, capable of simultaneous charging, come into play. This makes it possible to start with 40 kW today and plan towards higher power tomorrow.

OCPP compatibility also matters from the operator's point of view: thanks to remote monitoring, user authorisation and reporting, the station can be connected to a management platform, usage can be tracked and different pricing scenarios can be set up. In public or fleet use, this feature turns the station from just a device into a manageable service point — and makes the operational side of the investment easier too.

What is needed to install a 40 kW DC station?

DC fast charging requires a stronger electrical infrastructure than an AC wallbox. The general requirement is a three-phase supply of sufficient power (the BEVDC series takes an AC 380-480 V three-phase input) and installation by a qualified team. The exact electrical values — your facility's existing connection capacity, the board and cable cross-sections, the protective equipment needed and any requirement to increase capacity — must always be assessed on site by an expert. Correct sizing is essential both for safety and for the station to run without trouble.