Different types of charging

Normal charging

The most common method of charging your electric vehicle will always be at home during the night. Or during the day, at the workplace, if your employer has installed stations. In this scenario, simply connect the vehicle to a standard AC socket. The battery is charged via the vehicle’s on-board charger designed for slow charging for six to eight hours on average.

There are several charging modes:

• Mode 1: no control over charging
• Mode 2: control device incorporated into the cable
• Mode 3: charging and smart control from the station

In this, a standard domestic socket or specific wall box can increase the power. 

Accelerated charging

To accelerate charging, a few vehicles, the Renault Zoé, for example, have been designed to include a far more powerful on-board charger. With a capability of up to 43 kW, the charging time is reduced to under an hour. But this type of charging is only applicable to a restricted number of vehicles and the vehicle has to be connected to charging stations provided for this purpose, which are equipped with a T2 socket, in addition to domestic sockets. 

Rapid charging

Another solution to reduce charging time for all vehicles is to connect the battery directly to an outside charger incorporating all the power conversion. We then talk about Mode 4. The external charging station includes a developed communication protocol to ensure safe and optimised charging for the vehicle. Charging time normally aims at 30 minutes to one hour.

Several specific protocols and sockets can be found on the market:

• The COMBO protocol, in version 1 for North America and version 2 for Europe and Asia. 
• The CHAdeMO protocol, from Japan and equipping certain Asian vehicles
• The GB protocol for China

IES has designed a communication board incorporating all these protocols.

Rapid charging is ideal in many scenarios:

• For users without a domestic or private car park socket, who are still the majority in our towns
• For top-up charging at destination, when out shopping, going to the supermarket or parking in a public car park

Ultra-rapid charging

This involves minimising the charging time as much as possible, based on roaming charging, when taking the motorway for long distances. Vehicles can be charged in about ten minutes, assuming of course that their batteries can support this. The powers in play are very high, up to 150 kW and even 350 kW. IES is involved in development programmes to address these topics in the near future.

Electric buses

Given the huge battery capacity and to avoid weighing down buses with cumbersome on-board chargers, buses are often charged slowly overnight, relying in the main on external chargers. The powers delivered are around 50 kW, sometimes coupled together (as suggested by IES) to ensure flexible charging during the night.

Rapid charging is another solution, by installing chargers at each line terminus. The buses are then charged rapidly once they reach the end of the line via a pantograph system. The powers in play are high, in the order of 300 to 600 kW. This also implies installation constraints in the public space.