What is a phase?
A phase is a wire that brings 230-volt alternating current into your home. A home has a single-phase or a three-phase supply. With three phases you can use about three times as much power at once. You can see what you have on the main switch in your fuse box or on your energy bill; your network operator can also tell you.
Your car's charger sets the pace
Your car converts the alternating current into direct current for the battery itself. The on-board charger does that. It uses one or three phases, up to a certain current. So a Type 2 inlet doesn't automatically mean your car charges on three phases.
| On-board charger | Charging power |
|---|---|
| single-phase, 16A | 3.7 kW |
| single-phase, 32A | 7.4 kW |
| three-phase, 16A | 11 kW |
| three-phase, 32A | 22 kW |
Plug-in hybrids almost always charge on a single phase. Many fully electric cars charge on three phases at 11 kW; a smaller share can do 22 kW. Example: 3 × 230 V × 16 A ≈ 11 kW, and on a single phase 230 V × 16 A ≈ 3.7 kW.
The lowest power in the chain sets the pace
There are five links between the grid and your battery: your supply, the circuit in your fuse box, the charging station, the cable and the on-board charger. You charge at the lowest power of those five. A 22 kW charging station with a car that takes 11 kW charges at 11 kW. A three-phase car on a single-phase charging station charges at 7.4 kW at most.
How long does charging take?
Work it out like this: the number of kWh you want to add, divided by the charging power. For 40 kWh:
| Charging power | About |
|---|---|
| 3.7 kW | 11 hours |
| 7.4 kW | 5.5 hours |
| 11 kW | 3.5 hours |
| 22 kW | 2 hours (only if your car takes 22 kW) |
In practice it takes a little longer, because the battery charges more slowly towards the end and there is some loss. If you charge overnight at home, 11 kW is plenty for most people; if you don't drive much, 3.7 kW is often enough too.
What can your home supply handle?
A charging station gets its own circuit in your fuse box. Whether your supply has enough power depends on what else is running at the same time, such as a heat pump or induction hob. If you use a lot at once, a charging station with load balancing makes sure your supply isn't overloaded. You apply for a bigger supply with your network operator. Have your electrician take a look before you choose.
How to see what your car can do
Choose your car by make and model or use the number plate check. On your model's page you'll see the inlet, the number of phases and the charging power for each version. Then choose a charging station, charging cable or portable charger to match.