Charging basics: AC, DC and charging at home

Charging is where most first-time owners have questions. Here are the basics.

AC and DC

The battery stores direct current (DC). An AC charger supplies alternating current, and the car has a built-in charger that converts it. That conversion limits how fast AC charging can go. A DC fast charger does the conversion outside the car and can deliver much more power, so it charges faster.

Charging speed

Speed is measured in kW. You get the lower of two limits: what the charger can supply and what the car can accept. A powerful charger will not charge a car faster than the car allows. Check the maximum AC and DC charging rates of the specific car.

Why fast charging slows down

Charging is usually quickest when the battery is fairly empty and slows as it fills. For this reason, many drivers on trips stop at a fast charger for a part of the battery rather than waiting for a full charge. How much the speed drops differs between cars.

Charging at home

• Household socket: the slowest option. A normal socket was not necessarily designed for many hours of continuous charging, so have it checked first.
• Dedicated home charger: a wall unit installed by a qualified electrician. It is generally faster and designed for this use.
• Parking situation: if you park in a shared building or on the street, check whether you can install or access charging before you buy.

Public charging

Public chargers vary by operator, connector, speed and how you pay. Before you rely on one, check that it has the right connector for your car and that it works. This guide does not list specific networks, because these details change.

Before you decide

• Where will you charge on a normal week?
• Which connectors does your car use, for both AC and DC?
• Can the car do what you need on the longest trip you take regularly?