CCS, NACS, CHAdeMO, and GB/T: EV Connector Standards Explained

The plug determines who can charge at your site. The protocol underneath it determines whether the session actually completes. Buying in one region and deploying in another makes that difference expensive.

Connector choice is the decision that sets the addressable market for a charging site. A DC charger fitted with CCS2 cannot serve a Japanese vehicle on CHAdeMO, a Chinese vehicle on GB/T, or a pre-2025 Tesla on the Tesla plug, regardless of how much power it can deliver. The plug is a hard constraint that no firmware update removes.

This guide compares the five connector families in commercial use, and explains why the communication layer underneath them decides interoperability more than the shape of the metal does.

Why the Connector Is Only Half the Story

A DC charging session has two parallel conversations. On the power path, the charger delivers current through the DC pins once the vehicle has closed its contactors and confirmed isolation. On the signal path, charger and vehicle negotiate what that current will be: voltage target, maximum current, and the moment to stop. The signal path runs over a physical layer defined by the connector standard, carrying a protocol defined elsewhere.

That split matters when evaluating interoperability claims. A charger and a vehicle can share the same physical connector and still fail to complete a session, because the vehicle speaks one protocol implementation and the charger expects another. Physical compatibility is necessary. It is not sufficient.

CCS1 and CCS2: One Protocol, Two Plugs

The Combined Charging System extends an existing AC connector with two DC pins below it, which is where the Combo name comes from. CCS1 builds on the North American Type 1 connector from SAE J1772 and is used in the United States and Canada. CCS2 builds on the IEC Type 2 connector and is used across Europe and in most export markets outside China and Japan.

The practical difference is AC capability. Type 1 is a single phase connector, so CCS1 vehicles charge on AC at single phase power levels. Type 2 carries three phases, which is why European AC charging routinely reaches 11 kW and 22 kW while North American AC charging typically stops at 7 kW to 19 kW. For DC, both CCS variants use the same control and communication design and reach comparable power.

NACS and SAE J3400: What Actually Changed

The Tesla connector was opened to other manufacturers and standardized as SAE J3400. It uses the same compact plug for AC and DC, which removes the separate DC pins that make CCS bulky. For DC sessions it uses the same powerline communication approach as CCS, so the protocol lineage is shared even though the hardware is not.

The commercial effect has been faster than the technical one. Several large vehicle manufacturers announced NACS inlets for North American models, and charger suppliers responded with dual-cable or adapter-based configurations. For a site being planned now in North America, providing both CCS1 and NACS on the same post is the lower-risk specification, because the installed vehicle fleet will be mixed for years.

CHAdeMO: Still Installed, Rarely Specified

CHAdeMO was the first DC standard deployed at scale and remains common on Japanese vehicles and on chargers installed in Japan. It uses a large dedicated connector with a CAN bus communication layer, distinct from the powerline approach used by CCS. Early deployments were mostly 50 kW class, and later revisions pushed the ceiling far higher on paper.

For new procurement outside Japan, CHAdeMO is now a compatibility requirement rather than a growth path. Sites that must serve older Japanese vehicles often add a single CHAdeMO cable alongside CCS rather than specifying it across the whole site. The successor specification developed with Chinese partners, often called ChaoJi, targets both regions but is not yet a mainstream deployment standard.

GB/T 20234: The Chinese Standard and Its Revision

China runs a separate connector ecosystem under GB/T 20234, split into parts covering the general requirements, the AC connector, and the DC connector. The 2015 revision standardized the current widely deployed hardware, with typical DC limits around 250 A and 750 V. Its communication layer is CAN based, which is one reason Chinese vehicles and European chargers need active translation rather than a passive adapter.

A newer revision raises current and voltage capability substantially and introduces liquid-cooled cable assemblies for very high power charging. The practical point for buyers is that GB/T is not one specification. Confirm which revision a charger and a vehicle implement before assuming a session will work at full power.

The video above is a useful corrective to the assumption that one connector winning ends the problem. Standardizing the plug reduces the number of cables a site needs. It does not remove the protocol work, the certification work, or the mixed fleet that remains in service for a decade.

Why the Protocol Decides Interoperability

Two DC chargers with identical CCS2 cables can behave completely differently with the same vehicle. The differences sit in the communication implementation: how the charger handles the insulation test sequence, how it responds when the vehicle requests a voltage above the cabinet ceiling, how it reports a timeout, and and whether it supports the smart charging and bidirectional features the vehicle expects, which the V2G overview covers. A charger that mishandles one of those steps produces a failed session that looks like a vehicle fault.

This is why charger evaluation should include a compatibility test matrix against real vehicles, not only a certificate review. Ask a supplier which vehicle models have been tested against the specific firmware version you are buying, and what the outcome was on the charging levels that your site will actually deliver.

Dual-Standard Deployment: Planning for a Mixed Fleet

For sites that must serve more than one connector family, three deployment patterns cover most cases:

• Dual-cable posts, where one cabinet feeds two or four outputs of different standards, sharing power across them
• Separate posts on a shared power cabinet, which is simpler to service but occupies more parking area
• Adapter-based service, which is cheap to start and adds handling, wear, and failure points in the field

The dual-cable approach is the common answer for DC sites. A unit such as the four-gun DC charger or the DC fast charging station can be specified with mixed cable sets, so one cabinet serves CCS2 and CHAdeMO or NACS vehicles and allocates power dynamically. For higher power sites, the split liquid-cooled configuration separates the cabinet from the terminals and allows each terminal to carry a different connector. The full connector and power range is listed on the product pages.