What is the difference between AC and DC charging for electric cars?


AC, (or alternating current) charging converts electricity from the grid to DC (direct current) power using a converter in the car, while DC charging converts it externally.

Your electric vehicle battery uses direct current (DC) power. However, the electricity that comes from the grid (or from an outlet) is alternating current (AC). There are two different types of charging, depending on where the electricity is converted from AC to DC. In home charging, which is AC charging, the car’s on-board charger converts the AC electricity to DC and then sends it to the battery. The on-board charger has a built in speed limit on how quickly it can do this. The maximum speed is usually around 11 kW, which means AC charging can generally add 20-40 miles per hour. 

On the other hand, DC charging happens when the conversion to DC energy happens outside of the car. This is almost exclusively reserved for public charging stations, and the ones that cost quite a bit, at that. Since the electricity going into the car bypasses the on-board charging, it can refill the battery much faster. The current top speed is around 30 minutes to recharge 80%. 

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