According to the technology and usage characteristics of electric vehicle power battery pack, there are some differences in electric vehicle charging modes. Nowadays, there are generally three modes for choosing electric vehicle charging scheme: conventional charging, fast charging, and battery pack fast replacement system.
After the battery is discharged, it should be charged immediately (in special cases, it should not exceed 24 hours), and the charging current is relatively low, about 15A. This kind of electric vehicle charging is called conventional charging (normal charging). The charging method for conventional batteries is to use small current constant voltage or constant current charging, generally for 5 to 8 hours, or even 10 to 20 hours.
Because the rated power and current values are not critical, the charger and installation cost of conventional charging are relatively low; it can make full use of the low electricity period for electric vehicle charging, reducing the charging cost, and improving the charging efficiency and extending the battery life. The main disadvantage of the conventional charging mode is that the charging time is too long and it is difficult to meet the emergency operation needs.
The conventional charging method for conventional batteries usually takes a long time, which brings many inconveniences to actual use. The emergence of fast charging for electric vehicle batteries provides technical support for commercialization of pure electric vehicles. Fast charging for electric vehicles, also known as emergency charging, provides short-term charging services for electric vehicles parked for 20 minutes to 2 hours at relatively high current, generally between 150A to 400A.
Using fast chargers for electric cars, the charging time is short; the battery life is long (can be charged for more than 2000 times); there is no memory effect, and it can be charged and discharged with a large capacity. It can charge 70% to 80% of electricity in a few minutes. Because the battery capacity can reach 80% to 90% in a short time (about 10-15 minutes) similar to refueling time, it is not necessary to equip large parking lots when constructing corresponding charging stations. However, compared with conventional charging mode, fast charging also has some disadvantages: the charging efficiency of the charger is relatively low, and the corresponding work and installation costs are higher; due to the use of fast chargers for electric cars, the charging current is high, which puts higher requirements on electric vehicle charging technology and safety, and the metering charging design also needs special consideration.
