Charging Electric Cars

L. David Roper,,
17 September 2015



CHARGERS are in the vehicle. CHARGING STATIONS are outside the vehicle. A long cable connects the charging station to the charger in the vehicle.

There are two kinds of electric vehicles: Plug-In Hybrid Electric Vehicles (PHEVs) and Battery Electric Vehicles (BEVs).

Charging Stations

There are three standard types of CHARGING STATIONS:

  1. Level-1/120-volts AC (1.15 kW) Level-1 and Level-2 use the same cord, the SAE J1772: Uses any standard 120-volts electrical outlet. Electric cars come with a SAE-J1772 cord to connect to standard 120-volts outlets.
  2. Level-2/240-volts AC (3.3 kW or 6.6 kW or higher)
    1. The 2010-2012 LEAFs have the 3.3-kW charger; later years have the 6.6-kW charger. Level-2 charging stations usually are 7.2-kW, some are even higher, but the chargers in the car are usually not higher than 6.6-kW. The chargers in the EV have to have less power capability than the charging station.
    2. Many electrical companies make level-2 charging stations for inside or outside locations. Here is the Schneider charging station in our garage:
    3. Most 120-volts SAE-J1772 cords that come with electric cars can be converted to 240-volts to connect to 240-volts outlets similar to those used for electric stoves and clothes dryers. This costs less than most level-2 charging stations.
    4. The Tesla High Power Charger Wall Connector has 16.8-kW maximum power. Tesla is installing them across the U.S. The cord is not SAE J1772. Tesla Model S comes with one level-2 10-kW charger or two 10-kW chargers. The Tesla cable has adapters for 110-volts and 240-volts outlets.
  3. Level-3/480-volts DC (35-100 kW or higher). Called "fast" or "quick" charging stations. There are several standards for level-3 DC charging:
    1. CHAdeMO for Japanese and Korean cars: Most fast-charging station in the U.S. in 2015 use this standard. Roanoke has a CHAdeMO fast charger on Market Street behind the Market building. It cost $3/charge and is 35-kW maximum power.
    2. SAE Combo for U.S. and European cars:New charging stations being installed from 2015 on have a cable for both CHAdeMO and SAE Combo charging. One was installed in Blacksburg VA in 2015.
    3. Tesla very fast DC charging stations (Superchargers with an average of 5 charging stations at 120-volts maximum power; perhaps 170-kW later) across the U.S. to recharge Tesla-S batteries; and using them is “free” of cost (i.e., included in the cost of the car) for Tesla drivers. (A Tesla-S can now travel from Mexico to Canada charging at Superchargers with free electricity and across the United States on selected routes!) Tesla claims 170 miles range with 30-minutes of charging at Superchargers; that is 340-miles/hourl! Tesla Superchargers animation. Here is information about Tesla Supercharger sites: Note the map: Click on 2015 and 2016 to see how fast Tesla is adding Supercharger sites. Charging Teslas at Superchargers is free! It only costs ~$150,000 to set up a typical Supercharger, ~$250,000 if the power is solar PV. Tesla has offered to share its Superchargers with other electric-car brands. Here is information about the Tesla Supercharger (8 stations) at Burlington NC: Mimi’s Café is a great place to eat! Some of us are urging Tesla to install Superchargers on I-81. Tesla has an adapter to allow its BEVs to charge at Level-3 CHAdeMO charging stations:
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When to Charge Electric Vehicles

Charging Speed

Charging speed is measured in kW power. The following curves are from for fast-charging stations. They show that the speed decreases rapidly when charging reaches a certain percentage of a full battery.

Top curves: peak 50-kW; middle curves: peak 36-kW; bottom curve: peak 21-kW


An EV is "ice'd" when a Internal-Combustion-Engine vehicle is parked in a spot reserved for charging EVs.

Notices to put on cars that have ice'd your EV:


Musing about Electric Cars
When Will All Cars be Electric

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