AC vs DC Charging
Electric vehicles (EVs) are fitted with an onboard charger which converts alternating current (AC), the type of electricity powering home appliances, to direct current (DC), the type of electricity required to charge EV batteries.
An “AC Charger” is essentially an intelligent switch which informs the EV how much power it can draw, determined by the capacity of socket or electrical installation. Once the safety checks are completed it activates the switch to supply AC power to EV. The charge rate is limited by the vehicle’s onboard charger, typically up to 11kW, 3-phase. AC chargers are the most common and cost effective means of EV charging.
DC Chargers or “superchargers” deliver the fastest possible charge rate. The technology is more complex and expensive that AC charging technology since the AC to DC rectifier is located in the charging station. Large DC charge stations can deliver up 350 kW, however the charge rate will be limited to the EV, typically between 50kW and 100kW. The high cost of DC Charge stations and electrical infrastructure limits their application to public charging facilities on national highways or dedicated fast charging facilities.
Charging an EV involves the transmission of high current which poses a fire/safety risk if not conducted correctly.
- Never use an extension cord with a portable EV charger.
- Charging from a domestic socket is safe when the electrical installation was performed by a licenced electrician. If in doubt, rather charge at a lower rate (eg. 10 Amps).
- If the charger plug and/or the socket become hot during charging, stop charging and have the socket circuit tested by an electrician.
- Level 2 Charge Stations must only be installed by a licenced electrician who can issue a CoC for the installation. Ensure that these chargers are installed using a 6mm2 power supply cable as they can draw up to 32 Amps continuously for extended periods of time.
The Type 2 Plug is the standard plug for electric vehicle AC charging in South Africa and the European Union. The plug supports single or three-phase AC charging.
The Combined Charging System (CCS 2) is an extension of the Type 2 plug providing direct current (DC) contacts for high-power DC fast charging. This is the standard for all public DC Charge Stations in South Africa.
The Type 1 Plug is the standard plug for electric vehicle charging in the United States and Japan. The 1st generation Nissan Leaf is the only EV in SA that uses this type of plug.
The Combined Charging System (CCS 1) is an extension of the Type 1 plug providing direct current (DC) contacts for high-power DC fast charging. In Japan a dedicated CHAdeMO connector is used for DC charging.
Tesla uses its own charge plug and ecosystem for its supercharging network in the U.S but has adopted the Type 2 / CCS 2 standard in Europe. Tesla is expected to adopt the Type 2 / CCS 2 standard for South Africa.
Amps (A) is the measuring unit for electric current. South African domestic sockets can supply up to 16 Amps current.
Volts (V) is the measuring unit for electrical potential. South Africa’s standard domestic supply voltage is 230 Volts.
Watt (W) is the measuring unit for electrical power. Electric power is calculated by multiplying the voltage by the current. The power rating for a South African domestic socket is therefore 16Amps x 230Volts = 3.7kW.
Kilowatt-hour (kWh) is the measuring unit for electrical power consumption. It is used by electricity utility providers to bill users for the amount of electricity consumed. It is the energy provided in one hour by one kilowatt of power. The capacity of Electric Vehicle batteries is also measured in kWh.
Single Phase AC is the standard type of electricity supplied to most homes and small businesses, comprising of three conductors, Live (L), Neutral (N) and Earth (E). It is the most common means of charging EVs at your home or workplace, providing a maximum charge rate of 7.4 kW.
Three Phase AC is the type of electricity supplied to large consumers of power, including offices, factories, farms and large homes. It comprises of five conductors, three Live (L1, L2, L3), one Neutral (N) and Earth (E). 3-Phase (3P) AC charge stations are rated up 22 kW, although the majority of electric cars only support 11 kW 3-phase charging. A few earlier generation EVs do not support three phase charging.
Industrial CEE Sockets
Industrial CEE sockets are commonly used in factories to supply electricity to high-powered machinery and come in various power variants, distinguished by colour, diameter and number of pins.
While standard domestic sockets can deliver up to 3.7kW of power, CEE sockets can deliver up to 22kW of power for the fastest possible AC charging.
An electrician can install a blue, 32 Amps, 3-pole, single-phase CEE socket in your home for use with our 7.4 kW, Fast Portable Level 2 EV Charger.
For homes and businesses equipped with 3-phase power a red, 16×3 Amps, 5-pole, 3-phase CEE socket will deliver up to 11KW of power, the maximum AC charging capacity of most EVs. If you want to “future proof” your installation consider installing 32×3 Amps, 5-pole, 3-phase CEE socket which delivers up to 22KW for use with our highest rated 22kW 3-Phase Fast Portable.
There are three levels of electric vehicle chargers:
Level 1 chargers plug into a standard domestic socket and can supply up 16 Amps or 3.7 kW of AC power. A level 1 portable EV charger is usually supplied with an EV and provides the simplest, but also the slowest, method of charging an EV.
Level 2: chargers can supply between 7.4 kW and 22 kW of AC power and must be installed by an electrician into an electric circuit that can provide the required power. It enables the fastest means of AC charging at your home or workplace.
Level 3 chargers, also known as “Superchargers”, can supply up to 350 kW of DC power. They are mainly found at public charging facilities on national highways or dedicated fast charging facilities.
Whereas the efficiency of internal combustion engine (ICE) vehicles is measured in litres per 100 km, the efficiency of EVs is measured in kWh per 100 km. Larger or higher performance EVs will have a higher electrical energy consumption than lighter or lower performance EVs. In order to calculate the electrical running costs of an EV, one needs to know:
- the average electrical energy consumption (in kWh/100 km) of the EV, ‘x’.
- the price of electricity (Rands/kWh) from the electricity supply utility, ‘y’
Energy running cost per 100 km = x*y or
Energy running cost per km = x*y/100
In addition to the cost benefit, lower electrical energy consumption enables more range to be added per hour of charging.