The Elementary Process of EV Charging

We know that batteries have fixed positive and negative poles which need to charge with direct current. But the grid transmits alternating current, so what do we do?  

The purpose of a charger is to convert the alternating current of the grid into a direct current to charge the battery and adjust the output voltage or current.

Slow Charging Process

Generally, new energy vehicles have vehicle-mounted chargers. Limited by volume and cost, vehicle-mounted chargers are small and slow in charging, so this process is called slow charging.  

In the process of slow charging, the slow charging pile provides alternating current for the vehicles, so it is also called AC slow charging pile.  

Quick Charging Process

If the charger is placed in the charging pile, without the limitation of volume and cost and used in the circumstance of multiple charging mold blocks being stacked, the charging speed will be very fast and this process is called fast charging.

In the process of fast charging, the fast charging pile provides direct current electricity for the automobile, so it is also called DC fast charging pile.

The Speed of Charging

Generally use charging power to express the speed of charging, the greater the power, the faster the charging speed, and the calculation formula of power is as follows：

Power（P） = voltage（U）× current（I）

 For example, when charging fast：

     U = 350 V

      I = 200 A

Then the charging power is：

   350 × 200 = 70000 W = 70 KW  

70 KW means that it can be charged 70 KWh per hour, and according to the power, you can calculate how much the car is charged, the formula is as follows:

Energy (W) = Power (U) × Charging Time (t)

For example:

    Home slow charging pile power is fixed 7KW

    Charging time = 8 hours

Then the charging amount is:

    7 × 8 = 56 kWh

In the same way, the time required for slow charging can be estimated:

For example:

           Charge Capacity = 70 kWh  

Household Slow Pile Power = 7KW

  Then the time from zero to full:

              70/7 = 10 hours

Note: The charging power of fast charging is constantly changing, and with the increase of electric quantity, the power gradually decreases; while the slow charging power is relatively low, basically fixed and unchanged, and the change is as follows:

Therefore, the calculation of charging amount and charging time through the formula is only suitable for slow charging, and the time of fast charging is difficult to accurately calculate.

The Power of Various Common Charging Piles

1. AC Slow Charging                                                                          

2. DC Slow Charging

3. DC Fast Charging 

*The parameters of each model of charging pile are slightly different, the above data is for reference only 

4. DC Super Charging

The power of the above charging piles is only the maximum value. During the actual charging process, the power will be affected by many factors. 

At the same time, the charging power of the electric vehicle itself also has a maximum limit. If the maximum charging power of the vehicle is 60KW, even if use a 120KW charging pile, the maximum power will be only 60KW.