Why do EVs not have standardised charging connectors?

In his latest article, HEVRA‘s Peter Melville discusses the different types of electric vehicle charging plugs

If you’re not familiar with electric vehicle charging, it may surprise you to hear there are four different charging connectors in common use in the UK, and this is excluding some of the early models such as the Tesla Roadster and some lead-acid cars like the G-Wiz.

Type 1 socket

So why all of the different connectors? Firstly, most cars have two different connectors, one for AC, one for DC. And before you groan that there’s no standardisation here- there is a good reason for it. All batteries are DC, and mains electricity is AC, so to charge your car up from the mains, there needs to be some AC-DC conversion at some point. Vehicle manufacturers have quite sensibly decided to incorporate an AC-DC converter in the car, known as an on-board charger. This means, wherever you are, you can connect to the mains via a 3-pin plug and charge the car. It also means that all that is generally needed for a charging point is a relatively low-cost interface between the mains and the car (known as an EVSE for Electric Vehicle Supply Equipment).

So why do we need a DC connector as well? The answer is that the on-board charger is quite bulky, heavy, and expensive, and the faster we want it to work, the more so. So an on-board charger typically works at 16A or 32A depending on the vehicle- at mains voltage these are roughly 3.6kW and 7kW respectively. This is ideal for charging at home or at work, but when on a long journey, you don’t want to sit around for hours waiting to charge. For this reason, the car also has a DC connector. The AC-DC converter is now part of the charging station, and can be much bigger and more powerful than the one carried in the car. By connecting to DC, it bypasses the car’s on-board charger so is not limited to the maximum power rating. Typical DC charging power is 50kW, with the Hyundai Ioniq offering 100kW and Tesla offering120kW. This means a large battery can be topped up in around half an hour.

Improvements made
So, we’ve established the reasons for two connectors, so what else? The reason is that it was standardised, but then improved. The Type 1 connector, which you’ll find on Mitsubishi, Kia, GM, early Renault and Nissan and a handful of others, offers a totally safe system. The charger communicates with the EVSE (charging point), and identifies the cable used. The charging rate can then be decided so as not to overload the cable, the car or the EVSE. Only when everything is good does the power switch on, and as soon as the release handle is triggered, charging stops immediately. It’s a good piece of design and it works well.

Type 2

So what went wrong? The answer is the Germans didn’t like it. In the UK, most domestic properties have electricity delivered at roughly 230V, single phase AC, and the main fuse has a rating of 60-100A. In Germany, it’s quite normal to have three phase AC at home, but with a lower fuse rating of around 25A. Of course, with three phases, the power delivered to the house is around the same, but it means you’re rather stuck for charging your car at any decent speed. For this reason, German automakers agreed on a new connector, the Type 2, which offers the same communication as Type 1, but with an extra two wires to allow three-phase charging. This type is used by virtually all car makers except those mentioned with Type 1.

Just to clarify, a Type 2 connector on a car doesn’t mean it has three phase charging, and likewise a charging point or charging cable. But it gives the physical connection so that the manufacturer could offer it.

First agreement
There’s two types for DC as well, and this comes down to licensing. In the early days of electric cars, a group of Japanese carmakers realised the need for DC charging, and agreed on a standard called CHAdeMO. It consists of a large round connector, initially rated to 50kW and with communication via CAN-Bus, and it was agreed between, amongst others, Mitsubishi, Nissan, and Toyota. They then licence the technology to anyone who wants it, such as Kia and Citroën.

However, over in Germany where the new Type 2 connector was being used for AC, carmakers didn’t want to pay a licence fee for what was seen as a clunky, non-futureproofed technology. They added another two pins to the Type 2 connector (for DC+ and DC-) and invented what is known as the Combined Charging System, or Type 2 CCS.


So there you have it- the majority of new cars now have Type 2 for AC, and CCS for DC. However, some new cars and many older cars have Type 1 AC and CHAdeMO for DC. Some, such as the new Nissan Leaf, use Type 2 for AC but CHAdeMO for DC.

But even with these four connectors, there are exceptions to the above. Renault decided that rather than having an on-board charger, the existing inverter could be used in conjunction with the motor windings to convert AC to DC. So rather than having a DC connector, they can charge at up to 43kW through the Type 2 AC connector.

Tesla also use a Type 2 connector on Model S and Model X, but the exception is when using their own “Supercharger” charging network. The same connector is used, but relays in the car reconfigure the same pins to supply DC power instead. Needless to say, although they use a Type 2 connector, Tesla Superchargers will not connect to other vehicles.

HEVRA aims to help train and audit garages to ensure they meet its high standards, while also allowing hybrid and electric vehicle owners find garages near them. For more information, contact Peter Melville – training@hevra.org.uk and visit the HEVRA website to find out latest training dates.

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