Charging your electric vehicle

By Benchmark
11-02-2021
Charging your electric vehicle
Some drivers find the whole subject of charging an electric car a daunting one. Let us demystify the process for you.

First things first:

All electricity in the UK comes from the National Grid in a form known as ‘Alternating Current’ (AC). Car batteries need electricity to be in the form of a ‘Direct Current’ (DC). AC can be converted into DC in one of two ways: either by the car itself, or by the charger.

Electric charge goes into the battery via a cable with a plug at either end. EVs have inlets for connecting a charging cable, but they come in a variety of designs. Some vehicles have two charging inlets, one for AC charging and one for DC. The inlet(s) on the vehicle will depend on the vehicle brand and age.


CHARGING YOUR CAR AT HOME

Most EV drivers rely on charging their cars at home, it being the easiest and cheapest method. There are two charging options here:

3-pin household wall socket. The power is supplied to your battery as AC and the car converts it to the required DC. This is the slowest method of charging, taking eight hours or more, but is easily done when you’re not in a rush e.g. overnight.

Home charging unit. This is by far the better option, as dedicated charging units are quicker and have inbuilt safety systems. The Electric Vehicle Homecharge Scheme (EVHS) is a grant available to help fund professional installation. The charger is a compact weatherproof box that’s connected to your home electrical supply and generally attached to a wall. When you get home, simply plug in the charging cable that comes with your car.


SO, HOW LONG WILL A HOME-CHARGE TAKE?

This varies hugely, depending on both the battery and the power supply.

The size of your car battery is measured in kilowatt-hours (kWh). Check your handbook for details. The electricity from your home power supply is measured in kilowatts (kW).

There’s a formula to work it out:

 kWh ÷ kW = total charging time

For example, a car with a 35kWh battery will take five hours to fully charge, using a 7kW electrical supply.

35kWh ÷ 7kW = 5 hours


CHARGING YOUR CAR WHEN OUT AND ABOUT

There is a growing number of public charging points all around the UK, with more being installed every day. You can find them at service stations, car parks, supermarkets and even in some city streets. It does take a little thought and preparation when charging your car away from home, but there is plenty of technology to help you.

There are many apps available (such as Zap-map, PlugShare or ChargePoint to name but three) that can help you locate charging points that work for your car.

Public charging points are generally owned by private companies. Some require a monthly subscription, others offer a pay-as-you-go scheme. You sign up with each company to gain access to their charging points. You pay them for your charge, either via their app or using a card they provide. Some have charging cables attached to the unit, others expect you to use your own. There is one company, Instavolt, that doesn’t require membership or an app, but instead accepts payment using your usual contactless bank card. It’s likely that most charging payments will be carried out this way in the future, enabling drivers to use any charging point that suit them.

Some councils are fitting charging points within lamppost casings on the roadside. The London Boroughs of Hounslow, Richmond and Westminster, for example, have done so in order to encourage more people to go electric.


Public charging points come in different levels of power, speed and cost.

Fast chargers: rated between 7kW and 22kW, these draw AC current from the grid and rely on the car’s converter to turn it into DC. A small electric car can be fully charged in three to four hours using a fast charger. They are normally found in supermarkets, car parks or by the roadside.

Rapid chargers: these are mostly found at service stations on the motorway, where a speedy charge is needed so you don’t have to hang around for long. They use a high-power supply in either AC or DC. They can charge your battery to 80% capacity in as little as half an hour. NB. Charging slows down from 80% onwards in order to prevent damage to the battery.


ALL ABOUT PLUGS AND CONNECTORS

This can seem like a bit of a minefield at first. All EVs need a cable with plugs at either end in order to connect your car to the electrical source. Plugs come in several forms:

Type 1: less common these days, these five-point plugs came with the first plug-in hybrids (PHEVs) several years ago. They work with AC current for slow charging at home or with fast charging points but aren’t compatible with rapid charging points.

Type 2: the European standard, this type is the most common and can be used for all speeds of charging. Again, they work with AC by they have seven ‘pins’ instead of Type 1’s five. Most modern EVs come with a Type 2 charger.

CHAdeMO: a strange name, but this plug is suitable for use at rapid charging points. In this case, the conversion of AC to DC has already happened within the charging point, so the transfer of electricity to your battery is extra fast. This type of plug is commonly used by Asian manufacturers such as Nissan, along with the legally required Type 2, hence you might find two ports to choose from under the car’s charging flap.

Combined Charging System (CCS): also used for rapid charging, these are more commonly found in German cars such as Volkswagen. It looks rather like two plugs combined which, in effect, is exactly what it is. It consists of a Type 2 plug’s seven pins for AC, with an extra two DC pins below. Only the top part of the inlet is used for slower AC charging, then the whole thing is used with faster DC charging stations.

Different makes and models of car come with different cables and inlets. Your best bet is to consult your car’s handbook or manufacturer to see what additional cables are worth purchasing to keep your charging options flexible.


WHAT ELSE AFFECTS CHARGING?

The speed of a charge can also be affected by:

• Temperature – extra hot or cold weather

• How full your battery is before you start charging. The last 20% of capacity is slower to charge than the first 80%

• Your car battery. Different makes and models have different capacities