120 kW DC Fast Charger: Dual-Gun Sharing, Site Power and Real Charging Speed

Short answer: a 120 kW DC fast charger is a cabinet with about 120 kW of power modules and, usually, two CCS connectors that share that power. One car gets up to 120 kW only if it can accept it — in practice that means a higher-voltage vehicle, because a standard 200 A cable limits a 400 V-class car to roughly 80 kW. The bigger benefit on most sites is that two cars can fast-charge at the same time. A 120 kW unit needs about 130 kVA of supply (186 A per phase at 400 V).

What “120 kW” actually means

The power rating describes what the cabinet can convert from AC to DC at full load. Inside, the cabinet is built from several power modules — typically in steps of 20 to 40 kW — that are switched between the two connectors as cars arrive and leave.

How much of that power reaches a car is limited by three things, and the lowest one wins:

1. The cabinet — 120 kW in total, shared between connectors.
2. The connector and cable — current is the limit. Standard air-cooled CCS cables on chargers in this class are rated up to 200 A; CHAdeMO connectors on the same cabinet carry up to 150 A.
3. The vehicle — its maximum charging power, battery voltage, battery temperature and state of charge. Every car follows a charging curve that drops as the battery fills.

The current limit: why one car rarely gets 120 kW

DC power is voltage multiplied by current. With the cable limited to 200 A, the power one connector can deliver depends on the battery voltage of the car plugged into it:

Battery voltage while charging	Max. power at 200 A	Typical vehicles
350 V	70 kW	Smaller 400 V-class cars at low state of charge
400 V	80 kW	Most 400 V-class cars
450 V	90 kW	400 V-class cars near full charge
600 V	120 kW	Vans and buses with higher-voltage packs
750 V	120 kW (cabinet limit; current ≈ 160 A)	800 V-class cars

This is the most common misunderstanding in fast-charger purchases: a site owner buys 120 kW expecting each car to charge at 120 kW, and drivers of 400 V-class cars see about 80 kW. The charger is not faulty — it is physics. If the fleet you serve is mostly 400 V-class, extra cabinet power beyond about 80–90 kW per connector only helps when two cars share the cabinet.

Two cars, one cabinet: how power sharing works

Our 120 kW cabinets have two connectors and allocate power modules automatically:

Situation	Connector A	Connector B
One car connected, high-voltage vehicle	up to 120 kW	—
One car connected, 400 V-class vehicle	about 80 kW (cable current limit)	—
Two cars connected	about 60 kW	about 60 kW
Two cars, one nearly full	power shifts to the car still charging fast	tapering car keeps what it needs

For a retail car park or fuel station this matters more than peak power. Two cars at 60 kW each move more energy per hour than one car at 80 kW while a second waits — and the site needs one foundation, one grid connection and one cabinet to maintain.

Charging time: what to tell drivers

The time for a 10–80 % charge is the energy added divided by the average power over the session, which is always below the peak. The table uses a 60 kWh and an 80 kWh battery and ignores small losses; treat the figures as estimates.

Scenario	Average power	60 kWh battery, 10→80 % (42 kWh)	80 kWh battery, 10→80 % (56 kWh)
400 V-class car, alone on the charger	≈ 70 kW	≈ 36 min	≈ 48 min
800 V-class car, alone on the charger	≈ 100 kW	≈ 25 min	≈ 34 min
Two cars sharing the charger	≈ 55–60 kW each	≈ 45 min	≈ 60 min

Battery temperature has a large effect. In cold weather a battery that is not pre-conditioned can charge at a fraction of these rates; in very hot weather both the car and the charger may limit power to protect themselves.

Site power: what the grid connection must supply

	VT-DF120 / VT-DFC120 (IEC)	VT-DF120-NA (North America)
Supply	400 V AC, 3-phase, 50/60 Hz	480 V AC, 3-phase + N + PE, 60 Hz
Input current per phase (max.)	186 A	155 A
Apparent power (√3 × V × I)	≈ 129 kVA	≈ 129 kVA
Two chargers, no load management	≈ 258 kVA	≈ 258 kVA

How to use these figures:

• Transformer and connection. Add your other site loads and the planned chargers for the next few years. Many sites add a third or fourth charger within two years; sizing ducts and the transformer for that now is cheaper than digging twice.
• Load management. If the available capacity is lower than the sum of the chargers, a site controller or the CPMS can cap total power and share it — at the cost of slower charging at peak times.
• Protection and cable. The electrical designer selects the breaker, residual current protection and cable size from the input current, the cable length and the installation method under local rules (for example BS 7671, IEC 60364 or NEC Article 625). Do not size them from the kW rating alone.
• Demand charges. Where the utility bills peak demand, two 120 kW chargers can add a large monthly demand charge even with few sessions. Model the tariff before choosing between 120 and 180 kW.

60, 120 or 180 kW?

	60 kW	120 kW	180 kW
IEC input current per phase	93 A	186 A	279 A
One 400 V-class car (200 A cable)	≈ 60 kW	≈ 80 kW	≈ 80 kW
One 800 V-class car	60 kW	up to 120 kW	up to 180 kW (current-limited around 750 V and below)
Two cars at once	≈ 30 kW each	≈ 60 kW each	≈ 80–90 kW each
Typical sites	Fleet depots, hotels, offices with 1–2 h stays	Retail, dealerships, fuel stations, city hubs	Highway hubs, high-turnover city hubs

Read the table from the bottom up: start with how long vehicles stay and how many arrive at once, then pick the cabinet. A 120 kW unit is often the best value point for sites where two cars may arrive together and most stops last 30–60 minutes.

Our 120 kW models

	VT-DF120	VT-DFC120	VT-DF120-NA
Market	IEC (Europe, UK, Asia-Pacific, Middle East)	IEC	USA, Canada
Connectors	CCS2 + CCS2 or CCS2 + CHAdeMO	CCS2 + CCS2 or CCS2 + CHAdeMO	CCS1, NACS, CHAdeMO
Cabinet (W × D × H)	850 × 840 × 1850 mm	700 × 500 × 1700 mm	850 × 840 × 1850 mm
Cable length	6 m	5 m	6 m
Enclosure	IP54 · IK10	IP54 · IK10	NEMA Type 3R · IK10
Operating temperature	−20 to +55 °C	−20 to +55 °C	−25 to +55 °C
Back end	OCPP 1.6J · 2.0.1	OCPP 1.6J · 2.0.1	OCPP 1.6J · 2.0.1
Options	21” advertising screen, POS payment, 22 kW AC output, 4G	21” advertising screen, cable hanger, POS payment	POS payment, 4G

Choose the VT-DFC120 where space between bays is tight — city car parks and forecourts — and the VT-DF120 where you may want to upgrade the same cabinet family to higher power later. IEC versions are supplied with CE, UKCA and TÜV certification and North American versions with ETL and ENERGY STAR; we send the certificates for the exact model you order.

Before you order: six questions

1. What share of the vehicles you serve are 400 V-class and 800 V-class?
2. How often will two vehicles arrive at the same time?
3. How much capacity does the site connection have today, and what does the utility charge for peak demand?
4. Which connectors does the market require (CCS2 only for public sites in some markets, such as Dubai)?
5. Which CPMS will run the chargers, and has the model been tested with it over OCPP?
6. What is the upper temperature at full output, and how is the cabinet protected against dust or salt on your site?

Send us these answers through the contact form and an engineer will reply with a configuration.