Electric Vehicle Charging Guide

New Zealand’s light vehicle transport industry is set to undergo a transition to battery electric powered vehicles (EVs) at a pace likely to surprise most people.

Many New Zealander’s next vehicle will be an EV. This means rather than filling cars with petrol or diesel, your EV will be plugged in and charged just like your other mobile devices. The difference is that to efficiently charge an EV a specialised charging unit is required, one with enough grunt!

EV charging units can be installed at homes, workplaces and in public spaces. With the benefits of greater convenience and lower costs, the private chargers are expected to become the typical way to recharge EVs. However, public chargers will typically be higher powered fast chargers, so they too will play an important role in the charging network.  For example, for those without access to their usual chargers, when large distances are covered and when a quick charge is needed.

Understanding EV Charging

There are a number of electric vehicle charging connectors (plugs and sockets) to get familiar with and this can be a bit confusing at first. To help explain how you can charge your EV, the following insight to the way power is transmitted may help.

AC/DC Three and Single Phase Power
Electricity can be transmitted using either AC (alternating current – changes direction 100 times a second) or DC (direct current – a constant flow in one direction) and both have their pros and cons. AC might sound more complicated than DC but it allows efficient generation and transmission of energy over long distances to our homes and businesses and is the form available from your local electricity network. However DC is becoming increasingly important. DC is the form of stored energy that is available from batteries and also the form that most electronic devices run on. We all use both AC and DC power, meaning we have to convert our energy from one form to the other as needed. Most people take power from their local AC electricity network and convert it to DC power their electronic devices or their device batteries. To do this we use converters, commonly referred to as battery chargers or power adapters. Larger electronic appliances, like TVs, generally have these converters built in so we can plug directly into AC power without an adapter. Some appliances, such as heaters, can use AC directly. Three phase power is three separate AC power supplies in an arrangement that allows efficient generation and transmission of energy. This is how electricity is distributed by lines companies. Single phase power is an extension of one of these phases to supply smaller customers such as most homes.

Electric vehicles have a big battery that must be charged with DC electricity and that supply DC to its electric motor. To do this it must get energy from the AC electricity network.

AC Charging

Electric vehicles have a built-in, on board battery charger to convert AC to DC, which means the vehicle can be plugged directly into an AC supply. This method is more convenient since AC power is supplied direct to our home and workplace and AC charging units are relatively low cost. However, the onboard charging units have limited power ratings as they can only be designed with a limited power rating before they get too big and heavy for the vehicle and so the downside is it will take longer to charge. This potential downside is soon offset with convenience and the fact that you can charge your car where it is normally parked; for example at home overnight.

The following picture shows the use of an AC charging unit with an electric vehicle.

DC Charging

DC chargers are the answer to faster charging units.  With a higher powered charger sitting outside the vehicle there is no real limitation on size and weight. The DC chargers bypass the vehicle’s on-board charger and supply DC electricity directly to your car’s battery for a much faster charge time. Their cost is generally beyond households and businesses and are therefore mostly available at popular or convenient public spaces. The following picture shows the use of a DC charger with an electric vehicle.

Plug/Connector Standards

There are a number of different connector standards that are used with electric vehicles. But don’t panic, once you are familiar with these connectors it will be about as complicated as knowing whether your old car took petrol or diesel. Additionally these connectors are designed so you can’t put the wrong one in your car.

Most electric vehicles are fitted with both AC and DC charging inlets giving you the option of either charging method. Below are the main electric vehicle charging connector standards in use.

Type 1 (SAE J1772): Type 2 (IEC 62196):
This connector is designed for AC charging from a single phase supply. The Nissan Leaf has been New Zealand’s most popular EV and uses this connector and so charging units with this connector have been widely installed.
A fast DC charging connector based on Type 1 adds two large DC pins to the connector and is known as Type 1 DC CCS (combined charging system). These were widely installed at public fast chargers but are mostly being replaced with the Type 2 CCS connectors below.
This connector is designed for AC charging from a three phase supply and is often referred to as the ‘mennekes’ connector. A three phase supply is less limited and so this connector can be used with higher capacity AC chargers. Charging stations with this connector can usually be wired to take supply from a single phase system and in this case the car will be charged with single phase power at a slower charge rate. This standard is therefore more flexible and a good option to futureproof your EV charger. It is becoming the preferred standard and has been recommended by the New Zealand Transport Agency (NZTA) for public EV chargers.
A fast DC charging connector based on Type 2 adds two large DC pins to the connector and is known as Type 2 DC CCS (combined charging system).

Note: It is common for EVs to be fitted with only a DC CCS inlet however these vehicles are still able to be charged with AC charging units by plugging their Type 1 or Type 2 AC connector into the top part of the inlet.

ChademoTesla
The Chademo connector is designed for DC fast charging only. The Nissan Leaf has a Chademo inlet for DC charging and due to its early popularity has been made widely available at public fast chargers in New Zealand. This standard has also been recommended by the NZTA for public chargers.Tesla use their own charging connector standard which has been designed to charge vehicles with either AC or DC using the same connector.

Charging Time

Charger capacityTime to add 100 km rangeConnectors used
1.8 kW (8 A)11 hrsAC type 1 or 2
3.7 kW (16 A)5.4 hrsAC type 1 or 2
11 kW1.8 hrsAC type 2
22 kW55 minsAC type 2
50 kW24 minsDC
100 kW12 minsDC
150 kW8 minsDC
300 kW4 minsDC

The vehicle may also limit the charge rate for example the early generation Nissan Leafs are limited to 3.7 kW with AC charging. So if you use a higher powered AC charging station you won’t be able to charge the battery any fast unless you use a DC fast charger.