AC Level 1 Charging – Most owners get the energy their EV needs for a daily commute by plugging their car into a standard 120-volt home outlet and charging it overnight. This is called AC Level 1 charging. It is the slowest method of charging, but it requires no special equipment other than a dedicated electrical cable that comes with the car.
AC Level 1 charging provides an average of three to five miles of driving per hour of charging. For a typical commuter who travels 40 miles a day, it is possible to completely recharge the car overnight. BEVs that stay plugged in for 14 hours overnight can store power for up to 70 miles of driving.
AC Level 2 Charging – Many EVs also give owners the option of installing a 240-volt charging station in their garage, carport, or driveway. This is called AC Level 2 charging. It cuts charging times roughly in half, but requires installation of a dedicated electrical circuit (similar to that used for a clothes dryer) and the purchase of a charging unit that typically costs between $750 and $1,500.
Most AC Level 2 charging provides an average of about 10 miles of driving per hour of charging. This means a BEV with an 80 mile range can be fully recharged in 8 hours or less. If that’s not fast enough, some newer EVs are equipped with power inverters (the onboard component that changes AC to DC for charging the battery) that have twice the capacity of earlier designs. This doubles the miles of driving per hour of charge from 10 to 20, while cutting the overall charging time in half to roughly 4 hours – or four times the speed of AC Level 1 charging.
DC Level 3 Fast Charging – Some EVs are equipped with electrical connections for fast charging using a high-current DC power source. This is called DC Level 3 fast charging. It can recharge an EV four to six times faster than an AC charger – which means a full charge on the typical BEV can be achieved in less than an hour. However, the cost of the required high-voltage electrical circuit and special charging equipment (typically $15,000 to $25,00) makes DC Level 3 fast charging stations rare.
Charging plugs and receptacles for electric cars have been standardized among vehicle manufacturers. This allows a single charger to be used for multiple cars, and eliminates the need to buy a different charger if you buy a newer electric vehicle. At the present time, there are three EV charging connector standards in use.
SAE J1772 – The Society of Automotive Engineers (SAE) has issued document J1772 – Recommended Practice for Electric Vehicle and Hybrid Electric Vehicle Conductive Charge which sets standards for the charging cable, connector, and vehicle socket for plug-in electric vehicles. All EVs sold in the United States and Canada comply with J1772 standards for both AC Level 1 and AC Level 2 charging.
CHAdeMO – DC Level 3 fast charging is a relatively recent development, and it is currently available in the U.S. only on the Nissan Leaf and Mitsubishi iMiEV. DC fast charging of these cars is performed using a special connector that was developed by the Tokyo Electric Power Company and Mitsubishi. The standard for that connector is called CHAdeMO, a name created by combining letters from the Japanese words that mean “charge for moving”. The CHAdeMO standard has been implemented by several Japanese auto manufacturers.
SAE “Combo Connector” – In the interests of further commonality and cost reduction, the SAE recently finalized a new “combo connector” standard that combines the existing J1772 connector for AC charging with added terminals for DC fast charging. Virtually all North American and European automakers have voiced support for the new connector and plan to use it going forward. The 2014 Chevrolet Spark BEV will be the first car to use the new connector. It remains to be seen whether Japanese automakers will adopt the new SAE connector or stay with their existing CHAdeMO design.