If you’re in the market for an electric vehicle (EV), you may have noticed that some vehicles are built to different charging specifications and, as a result, public charging stations feature different connectors. This situation marks quite a departure from the typical one-size-fits-all nozzle at the gas pump, but we can assure you that the different EV plug styles are not confusing.

In the US, you will only encounter four connector types: SAE J1772, CCS, CHAdeMO and Tesla’s proprietary model. Moving forward, you may only need to worry about one.

One AC connector is universal

All the latest EVs can be charged via the connector known as SAE J1772, also known as a J plug. This plug delivers AC (alternating current) power. It contains five pins, three of which are analogous to the three prongs on the plug of a typical household appliance.

Looking at the plug head-on, the top left pin is the “hot” one that carries AC power, while the pin next to it can be neutral or hot depending on the source voltage. The center-bottom pin is ground. To the left of this pin sits the “proximity pilot”, which tells the EV that a plug is inserted and prevents driving until the connector is disconnected. It’s also responsible for discontinuing charge as soon as the user activates the release lever, which keeps users safe from shock and ensures sparkless disconnect. Finally, the last pin on the bottom-right is called “control pilot.” It’s responsible for relaying charge level information between the car and the electric vehicle supply equipment (EVSE).

As we explained in an earlier blog post, AC charging with this connector is typically done at home or at a public charging station. Using a basic power outlet in your home with the charger that comes included with your EV will yield under two kilowatts of power transferred to the battery, which is only good for a few miles worth of charge per hour. This is why many people elect to install a high-amperage, 240-volt receptacle near where they will park their EV, and purchase a home EV charger that can deliver more charging power.

The J plug sends power to a rectifier (frequently called an onboard charger) built into each EV, which converts AC energy into DC (direct current) energy that is necessary to charge the battery. This device has a maximum power rating, meaning that it has a cap on how many kilowatts of power it can handle at any time. For instance, the 2020 Polestar 2 cannot accept more than 11 kW of AC charging, while the second-generation Nissan Leaf is capped at 6.6 kW.

DC fast charging connectors differ

Tesla’s connector is designed to work with Tesla vehicles only. It can supply AC and DC power to the car. If a Tesla owner is in a situation where only a standard charging cable is available, they may use an adapter to plug in. Tesla’s DC Supercharger network will likely be opened up to owners of vehicles from other manufacturers, provided they own a Tesla-to-CCS adapter.

CCS (Combined Charging System) connectors derive their design from the J plug. The main addition is a couple of large pins at the bottom of the assembly. Those two pins supply DC power at the source, which takes a direct route to the battery by bypassing the internal rectifier. This enables much faster charging, as the rectifier’s low voltage ceiling is eliminated. DC charging, also known as Level 3 charging, can send as much as 350 kW to the battery, a number which will likely rise in the future.

Thanks to the design of the CCS connector, most vehicles don’t need a separate inlet for DC charging. For Level 1 or 2 charging, a J1772 connector is plugged into the top half of the inlet. For Level 3 DC fast charging, the CCS connector can be plugged into the same spot; there may be a protective cap covering the two DC pin inlets that you need to remove before you can get going.

Yet another kind of DC connector exists, as we’ll explain below.

What is CHAdeMO?

This DC charging protocol was developed by the CHAdeMO association in 2010 and backed by Japanese automakers. It consists of a special connector that is not interchangeable with the inlets previously discussed. CHAdeMO gets its name from the Japanese phrase “Ocha demo ikagadesu ka,” which translates to “How about some tea?”, drawing a parallel between the time it takes to charge an EV via DC fast charging and how long it takes to brew and enjoy a cup of tea.

While CHAdeMO is standard in Japan, it has shared the spotlight with CCS in North America. EVs manufactured by Mitsubishi and Nissan, including the very popular Leaf, arrived in the US with two charge inlets: SAE J1772 for AC charging, and CHAdeMO for DC charging.

One significant point of differentiation between the CHAdeMO and CCS protocols is the ability to perform bidirectional charging. For years, only CHAdeMO vehicles were capable of discharging their batteries to power an external load. This is expected to change when the CCS electronic communication protocol is revised in the coming years to allow for this functionality.

What will become of CHAdeMO in the US?

EV charging in America is about to become standardized, with the CCS Combo inlet design set to replace CHAdeMO even in vehicles from Asian manufacturers. Kia switched teams in 2018, and Nissan announced that its new Ariya electric crossover will not use CHAdeMO either. All of this means that we can expect the next wave of public charging stations to omit CHAdeMO connectors. In 2021, Electrify America stated it would do just that during its Cycle 3 investment. However, a robust network remains in place for the remaining CHAdeMO vehicles on the road.

One connector after all

With a space-saving design that avoids the need for a neighboring DC inlet by building upon the already-standardized J plug, and near-universal acceptance from automakers, CCS is poised to take over the American market. Soon, you will only likely encounter CHAdeMO connectors if you are buying a used EV from a Japanese manufacturer. With one agreed-upon charging standard in North America going forward, the path to mass EV adoption becomes more straightforward.












Photo by Denys Rodionenko on Unsplash