AC charges over hours, DC over minutes.

The battery of an electric car stores direct current. The grid supplies alternating current. A converter sits between the two, and the only question is where it sits. AC stands for the alternating current, DC for the direct current.

With AC charging the converter sits in the car. The charging station releases the supply, watches the cable and meters what flows. The on-board charger sets the pace, commonly 11 kW and occasionally 22 kW. A car with a single-phase charger draws only 3.7 kW even from a 22 kW wallbox. That keeps the wallbox small and affordable.

With DC charging the converter sits in the pillar. It is the size of a cupboard, actively cooled and needs a heavy grid connection, often with a transformer of its own. In return it delivers 50 to 400 kW straight to the battery. Purchase and connection cost many times a wallbox.

In Europe AC runs through the Type 2 plug. DC adds CCS: the same Type 2 plug with two extra contacts underneath. A car with a CCS inlet charges on both, overnight at the wallbox and en route at the pillar. The older CHAdeMO plug still turns up on existing pillars, the Type 1 plug hardly at all.

An example with a 60 kWh battery: at 11 kW a full charge takes around six hours, at 22 kW around three. A 150 kW DC pillar takes the same battery from ten to eighty per cent in roughly twenty minutes. The last twenty per cent are slow there as well. Towards the end the battery pulls the power back itself.

Dwell time decides the hardware. Where vehicles stand for hours, AC is enough. Purchase and grid connection then cost a fraction. DC pays off where vehicles only stop briefly.