What you need to know about charging an electric car

We’re all experts in charging our phones; we do it at least once each day. Charging an electric car is similar, but more complicated – complicated enough to need a guide. Here’s ours.

Charging basics

Kilo-whats?

The amount of electricity your EV battery will hold is measured in kilowatt-hours (kWh). Bigger batteries take longer to recharge. The first Nissan Leaf models had a 24kWh battery, while 60kWh or so is typical of more recent models.

You’ll hear EV nuts talk about 'state of charge' or see it abbreviated as SOC (we use it later on). A 60% state of charge in your EV is no different to seeing 60% battery remaining on your phone.

Socket type

Your car will have charging sockets for AC and DC charging cables (note, most plug-in hybrid electric vehicles only have an AC charging socket):

• Alternating current (AC) charging is slower – AC is the standard current that comes out of all the plugs in your house, and so it’s how you’ll charge your car at home. And it’s how you’ll charge at destinations where you park for longer periods.
• Direct current (DC) is the type of current that batteries hold and discharge, and is how roadside chargers quickly fill up your battery.

There isn’t just one standard socket – that would be too easy. The charging stations you use need the right plug to fit your car.

On-board charger

Your car has an on-board AC charger that’ll only charge so fast. For example, an AC wall box might be capable of charging at 7kW, but an older Nissan Leaf will only accept 3.6kW AC, so that’s all you’ll get. DC charging bypasses the car’s on-board charger.

Charging at home

Usually you’ll charge your EV at home because it’s the cheapest and most convenient way.

You’ll need a garage or driveway so you can access a power point or install a dedicated charger. If you park on the street, life with an EV is going to be tough.

Trickle charging

An AC trickle charger plugs into a regular three-pin wall socket. Your garage will likely have a few, but it’s not the best way to charge. It’s very slow, adding just 2kW per hour, so overnight you’ll add only 16-18kWh. You can buy a trickle charger and cable for about $600. It’s worth keeping one in the car for emergencies, but it’s not recommended as your main charging option.

Wall box charging

Wall boxes are dedicated AC chargers you install inside a garage or outside on a driveway. They use dedicated heavy-duty wiring to a breaker on your home switchboard. That makes them safer than using a three-pin plug and they can charge faster. If you’re investing in an EV, it’s essential to budget $1500 to $2000 to get one professionally installed.

Many wall boxes come with a cable attached (get the right one for your car’s AC charging socket), or a socket so you can attach a separate cable (which can be useful to keep in your car to use at a destination charger).

Most installations are single-phase, with a typical charging rate of 7kW per hour. That’s enough to recharge most modern EVs from empty overnight. However, you rarely do that because most of the time you’ll top up from a higher SOC. You can install a wall box charger to a three-phase electricity supply to lift its charging rate to 22kW per hour, but that’s an unnecessary cost unless you already have three-phase at home.

Most wall boxes are smart and connect to an app, so you can control your charging remotely with a timer and see how much electricity you use. Some are set up to work nicely with solar panels.

Charging on the road

On longer journeys away from home, you’ll need to top up your battery on the roadside. Your main considerations are where to stop, and how long it will take to get back on the road.

Roadside chargers aren’t as ubiquitous as petrol stations. The final few are being added in less populated and less frequently travelled areas of the South Island, so there is at least one every 75km along the State Highway network.

But as more of us drive EVs, more chargers are needed, and those we have need to be faster to recharge our cars, so we don’t get charger-congestion. Both of those things are happening.

Fast DC charging

Roadside charging uses DC, which is much faster than charging at home. Most of the current roadside network will charge your EV at up to 50kW per hour. The latest hyper-rapid chargers (currently installed at Bombay, Kaiwaka and Taupō) can charge at up to 300kW. Many more hyper-rapid chargers are planned.

Your car might not charge at the full rate available. Most EVs can charge at up to 50kW, but only a few can make full use of the 300kW hyper-charger speed. Your car also manages the DC charging to protect its battery from damage. Charging is fastest when the battery is close to empty and slows down considerably above 80% SOC. Most DC chargers limit charging to 95% SOC.

On the road, it’s useful to think of how many kilometres you’re adding, not how many kilowatt-hours. In a mid-sized model like a Hyundai Kona, a good rule of thumb is that using a 50kW charger for 15 minutes adds about 50km driving range. Plug a Porsche Taycan into a hyper-charger and you’ll add up to 300km every 15 minutes.

ChargeNet

Most of the roadside chargers you’ll use are installed and managed by ChargeNet. The network has 282 charge points spread throughout the country, with 60 more under development. Many locations can only charge one car at a time, but more recent additions to the network have twin chargers. The latest hyper-charger locations can charge up to six cars at the same time.

Once signed up to its system, you just plug in your car and use a key tag with radio frequency identification (RFID) to activate the charger. Once you’re done, your credit card is billed automatically. It’s not as cheap as home charging – you’ll typically pay 25¢ for every kWh you add and 25¢ for every minute you’re charging.

ChargeNet has an app that shows the network status, so you can see if the charger is working and available. It also shows your live charging session, so you can monitor it while you’re off getting a coffee. There’s a 24/7 helpline, too.

OpenLoop

This is a network of independent roadside chargers managed through the OpenLoop app. Most of its chargers are around Auckland, though they stretch to Ohakune and Napier and there’s one lonely South Island charger, in Wānaka.

The OpenLoop app works in a similar way to the ChargeNet app, but you use a QR code on the charger to start a charging session, and you preload the app to pay ‘at the pump’. Quite a few of the OpenLoop chargers cost nothing to use.

Zero

Meridian Energy is installing a network of AC and DC chargers, starting with locations in Auckland, Wellington and Canterbury. Most of its network will be slower AC destination chargers, but it will also include some DC chargers. Similar to ChargeNet and OpenLoop, you’ll need an app to access the Zero network and pay for your charging.

Charging a Tesla

Tesla has its own charging network. You’ll see banks of four or six Tesla ‘superchargers’ installed at the roadside, often next to a ChargeNet charger. Typically the Tesla superchargers charge at up to 120kW and have their own variable pricing. Many destination chargers also only work with Tesla cars. Currently, Tesla owners can use other charging stations, but drivers of other brands of EV can’t use Tesla ones. In November 2021, Tesla announced it will open its network to drivers of other EVs, starting with a pilot programme in the Netherlands. There is no indication of when this might affect New Zealand EV owners.

Destination charging

As EVs become more common, chargers are popping up wherever people park up for a while, including at big-box retailers, shopping centres, tourism locations, hotels and motels.

Destination chargers usually are equivalent to fast home charging (7-22kW), often free to use or offered as a complimentary service, and useful for topping up a car while you’re busy doing something else.

You can find these chargers on the global PlugShare app and website – it’s the grandaddy of EV charging maps. It also shows roadside DC chargers and the Tesla-only chargers. Usefully, you can filter by plug type, so you only see chargers that’ll work with your car.