AC charging is the simplest kind of charging to find – outlets are everywhere and almost all EV chargers you encounter at homes, shopping plazas, and workplaces are Level 2 AC chargers. An AC charger provides power to the on-board charger of the vehicle, converting that AC power to DC in order to enter the battery. The acceptance rate of the on-board charger varies by brand but is limited for reasons of cost, space and weight. This means that depending on your vehicle it can take anywhere from four or five hours to over twelve hours to fully charge at Level 2.
DC Fast Charging bypasses all of the limitations of the on-board charger and required conversion, instead providing DC power directly to the battery, charging speed has the potential to be greatly increased. Charging times are dependent on the battery size and the output of the dispenser, and other factors, but many vehicles are capable of getting an 80% charge in about or under an hour using most currently available DC fast chargers. DC fast charging is essential for high mileage/long distance driving and large fleets. The quick turnaround enables drivers to recharge during their day or on a small break as opposed to being plugged in overnight, or for many hours, for a full charge. Older vehicles had limitations that only allowed them to charge at 50kW on DC units (if they were able to at all) but newer vehicles are now coming out that can accept up to 270kW. Because battery size has increased significantly since the first EVs hit the market, DC chargers have been getting progressively higher outputs to match – with some now being capable of up to 350kW. Currently, in North America there are three types of DC fast charging: CHAdeMO, Combined Charging System (CCS) and Tesla Supercharger. All major DC charger manufacturers offer multi-standard units that offer the ability to charge via CCS or CHAdeMO from the same unit. The Tesla Supercharger can only service Tesla vehicles, however Tesla vehicles are capable of using other chargers, specifically CHAdeMO for DC fast charging, via an adapter.