Guide to charging an electric car

Slow chargers, fast chargers, and rapid chargers; a guide to charging an electric car

Chris Knapman
Feb 28, 2018

If you’re considering buying an electric car, one of the major considerations is how you will charge it. If you have off-street parking at home the obvious solution is to plug the car in overnight, taking advantage of cheaper Economy 7 electricity tariffs in the process.

However, you can also find charging points at many workplaces, car parks, motorways services and so on, adding to the convenience of electric vehicle (EV) ownership, as well as making longer journeys possible. Whatever option you choose, it’s worth knowing that chargers are divided into three types:

  • Slow chargers
  • Fast chargers
  • Rapid chargers 

Slow chargers (3kW)

A slow charger can charge at up to 3.6kW hours, although they are generally referred to as 3kW units. They are most commonly installed at home and can deliver a full charge in about 8-12 hours, although it can be longer for EVs with larger batteries.
Many manufacturers will supply a wall-mounted slow charger when you buy a new electric car, or if not, there are Government subsidies in place that provide you with £500 off the cost of purchase and installation. Without subsidies, 3kW chargers typically cost between £350-450.
There’s also nothing to stop you charging an electric car from the same three-pin socket that runs your toaster or television, and most come equipped with a lead for this very purpose. However, it takes longer than a dedicated wallbox and doesn’t have built-in safety features, so three-pin charging is generally only used by electric car owners when no other option is available.

Fast chargers (7-22kW)

Home fast chargers operate at approximately twice the speed of slow chargers, meaning that a full charge takes about 4-8 hours. They cost more to install and you’ll need a car that is compatible with fast charging for it be able to draw the full charge. If not, a fast charger will still work, but only at the rate the car can accept. These fast chargers generally cost more than £1000, but can also be bought with a Government subsidy to reduce the cost.
You’ll also find fast chargers at some workplaces and in public places such as supermarket car parks, which in some cases can deliver up to 22kW of power for even faster charging, taking a compatible car’s battery from flat to full in a couple of hours or so.

Rapid chargers (43-50kW, and 120kW)

Rapid chargers deliver between 43kW and 50kW (or 120kW in the case of Tesla’s Supercharger network) and can give an electric car an 80 per cent boost in battery power in as little as 30 minutes. They are often found at motorway services, the idea being that by the time you’ve stretched your legs and had a cup of coffee, your car’s battery is topped up and ready to go.
Not all EVs can accept rapid charging, and due to the amount of power required the chargers can’t be installed at home.

Example electric car charging times

Renault Zoe Z.E. 40 Nissan Leaf 40kW BMW i3 94Ah
Driving range (real-world approx) 150 miles 150 miles 120 miles
Slow charger 13.5 hours 16 hours 11 hours
Fast charger (7kW) 6 hours 8 hours 4.5 hours
Fast charger (22kW) 2 hours 8 hours 3 hours
Rapid charger to 80 per cent capacity 1 hour 40-60 minutes 35 minutes 

Sign up for public charging

Public charging points are run by a variety of companies, most of which charge for the use of their electricity in the form of a monthly subscription or on a pay-per-use basis. Either way you will need to sign up with the relevant provider to gain access to their charging points, which you then unlock either by swiping a membership card or using a dedicated app.

Unless you plan to visit the same public charging points exclusively, it is worth signing up with two or three providers to ensure you’re covered as and when you need to top up.


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