Electric Vehicle Charging

Available charging options are a key factor that will drive future sales of electric vehicles. For folks involved in distribution system planning and engineering, there are a number of concerns related to Electric Vehicle Supply Equipment (EVSE). These include:

• Peak demand (kW or MW)
• Location
• Load profiles of the EVSE (load vs. time)

While there’s not a formal standard around the peak demand of EVSE, a convention that get used frequently is to refer to the charging as Level 1, Level 2, or Level 3.

• Level 1:120 V AC Supply; Peak demand of 1.2 – 1.8 kW
• Level 2: 240 V AC Supply; Peak Demand of 3.6 – 19.2 kW
• Level 3 DC Fast Charging: Peak Demand up to 250 kW

Obviously the battery charging rate is lowest with Level 1 and fastest with Level 3.

The above are generalities, and values for specific chargers may lie outside of the ranges I listed above. Also the actual maximum rate of charging is dependent upon many factors, including the vehicle and its firmware settings, the state of the battery, battery management system, the charger’s management system, etc.

The image below shows a Tesla connected to a supercharger (Level 3 DC Fast Charging) which has a maximum available capacity of 150 kW per vehicle.

The photo below shows the bank of six superchargers that are serving that site. Each supercharger serves two vehicles spots, so 12 vehicles can be served simultaneously. Note the “1B” at the bottom of the pedestal in the photo above. The spot next to it is “1A”.

The below is the nameplate on one of the superchargers. Note that the input voltage is 380-480 VAC, and the output voltage is 50-410 VDC. The bank of superchargers is fed by a three-phase 13.2 kV/480 V, 750 kVA transformer.

The above station that I discussed is just one example of a supercharging station, but I hope it gives you an idea of the amount of electric load. The photos above were from a Tesla V2 charging station – in 2019 they introduced the V3 charging station, which has a maximum charge capability of 250 kW per vehicle. The maximum demand of supercharging stations will be dependent upon number of vehicle spots, maximum power draw of the vehicles, software settings of the supercharging stations, and other factors.