How electric vehicle charging works

Forget the green and black pumps: the time for fossil fuels is over. From now on, it’s all about charging, so get ready to plug in and embrace the kilowatt hours.

How does EV charging work?

Your electric vehicle (EV) has a rechargeable battery that supplies all the power for the car, which means that it has to be charged regularly to keep the car going. It’s just like your mobile phone: in fact, an EV car battery uses the same chemistry – lithium ion. 

The process is pretty simple. You plug the charger’s cable into your car (or your car’s charger cable into a charger) and it starts to take on electricity. How long it takes will vary, as we’ll explain in a minute, but remember that the first 80% of the battery will charge quickly, but then it will slow down, so as not to damage the battery as it reaches 100%.

Topping up to 80% when you can, is a technique that many EV drivers use, because it’s the most efficient use of your time (with a rapid charger, you can get to 80% in 30-40 minutes: with an ultra-rapid charger, that can be as little as 10 minutes). On the other hand, a slow trickle charge overnight on a lower-powered home charger is just as effective.

EV charging locations

In the UK there are four different types of locations you can charge your electric vehicle;

1. Charge at home 

You can charge your electric car at home using a three-pin domestic plug (approx. 3kW) or you can have a wallbox charger unit installed (approx. 7kW - 22kW) Read our Charging at home guide for more information.

2. Charge at work 

You can also charge your electric vehicle at work. More and more businesses are installing electric vehicle chargers at their sites for use by their employees. Depending on the equipment thats been installed, the charger could be anything from a commercial wallbox charging unit (approx. 7kW - 22kW) all the way up to a rapid charge point (approx. 50kW) Read more about how to charge your electric car at work in our Charging at work guide. 

3. Charge at public locations 

You'll find you can even charge your EV at numerous public locations all over the UK. From retail shopping centres, supermarkets, leisure facilities or tourist attractions using fast public chargers (approx. 7kW, 11kW or 22kW) to our very own Electric Forecourt® in Braintree, which allows up to 36 electric cars to be charged at any one time.

UK charging infrastructure is improving every day. The easiest way to find all of the charge points in your area is to use Zap Map.

4. Charge at motorway service stations

You can charge your electric car at any number of public chargers using a rapid public chargers (approx. 50kW - 120kW) like those you'll find on the GRIDSERVE Electric Highway.

What does kW and kWh mean?

OK, so there are some numbers you’ll need to get used to with EVs, but they’re less confusing than the ones relating to cars with internal combustion engines.

Kilowatt hour (kWh)

Instead of a car being defined by its engine capacity – expressed in litres – it’s now defined by its battery size. EVs have a battery that can have a capacity anywhere between 30kWh and around 100kWh, with the numbers indicating the total of the battery's energy storage over a specific time. On average, electric cars consume 34.6kWh to travel 100 miles, so a 30kWh battery will have a range of less than 100 miles.

Kilowatt (kW)

The other number you’ll need to understand is the potential output of a charger, because different units have different charging speeds. You can charge from a domestic 3kW three-pin plug, but it is s l o w. Next up are 7kW and 22kW chargers, either home-charging wallbox units or on-street public chargers, which usually take three or four hours to achieve an 80% charge.

‘Rapid’ chargers are rated at 43kW-50kW and can be found at motorway service stations, such as ones that are part of the GRIDSERVE Electric Highway, for example. In just over half an hour, you can get an 80% charge. In recent years, we’ve started to see higher-power chargers that can deliver electricity at 100kW, 150kW and even 350kW. An 80% charge takes just 10-15 minutes.

Not all EVs can charge at these higher speeds, however. Older EVs often only charge at up to 50kW, so even if you plug them into a new ultra-rapid charger, they will only charge at that rate. More recent models – especially at the more premium and luxury end of the scale – can charge at these high speeds.

Different electric vehicle connectors

EV charging cables have a connector at each end: one plugs into the car, the other into the charger. Which connector you use depends on your EV and the type of charger you use.

Five-pin Type 1 and seven-pin Type 2 connectors are for use with slower AC chargers, such as home or workplace wallboxes. For faster DC chargers, Type 2 also works, along with Combined Charging System (CCS) and Chademo connectors. Most EVs use Type 2 or CCS cables, with Chademo possibly going the way of Betamax video.

How much does it cost to charge an electric car?

If you have off-street parking and can fit a charger on the outside of your house, the electricity costs whatever you pay under your standard domestic tariff. This means you should be paying around 17.2p per kWh (at late 2021 prices).

If you have a 60kWh battery, that means you’re paying around £10 for a full charge. When was the last time it cost you a tenner to fill a car with petrol or diesel?

If you don’t have access to a charger at home or at a workplace, and have to rely on public charging, you’ll be paying somewhere between 30p and 69p (for the ultra-fast rapid chargers) per kWh. 

Read more about electric vehicle charging costs in our EV Charging costs guide.