Which chargers suit which site?
The shops ask for something extra: AC charge points for staff, who park for eight hours.
The developer adds six 22 kW points at the far end of the car park, on the existing connection.
The questionWhy do staff get slow chargers and travellers fast ones?
| Typical stay | Power | Current | |
|---|---|---|---|
| Motorway hubtravellers on a long trip | 20 to 40 min | 150 kW and more | DC |
| Retail car parkshopping, a meal | 30 to 90 min | 50 to 150 kW | DC |
| Workplacestaff during the day | 8 hours | 11 to 22 kW | AC |
| Hotelguests overnight | 10 hours | 11 to 22 kW | AC |
| Residential streetresidents without a driveway | overnight | 11 to 22 kW | AC |
Typical values, not rules. A site can combine both, as this retail park does.
Time makes up for power
Energy is power multiplied by time. A car that stands for eight hours gets 88 kWh from an 11 kW charge point, more than a day's driving needs. A car that stops for 25 minutes needs a fast charger to get the same in time.
That is why fast chargers stand where stops are short, and slow chargers where they are long. The units are explained in eMobility and EV basics, stop 04.
Cost per charge point
- AC charge points are compact and need little grid capacity each. Many can stand on an existing connection.
- DC chargers bring , cooling and usually a new connection, so each one costs much more. They have to be used often to pay back.
What is inside each kind is the subject of Charging hardware.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
A car stands at work for 8 hours on an 11 kW charge point. How much energy can it get?
Energy equals power times time: 11 kW × 8 h = 88 kWh, limited only by what the battery can take.
Why do fast chargers stand mainly where stops are short?
Time makes up for power, and the other way round. With only 25 minutes, power has to be high.
Why could the AC points for staff open months before the fast chargers?
Six AC points fit within the existing connection. The fast chargers wait for the new medium-voltage connection.
- Power electronics Semiconductor circuits that convert and control electrical energy: in the car mainly the inverter for the motor, in a DC charger the rectifier and the DC/DC converter. eMobility and EV basics, stop 03 Glossary