By Irena Zhuravchak and Volodymyr Ilchuk | Tuesday, June 27, 2023 Charging a battery using the constant-current/constant-voltage (CC/CV) method involves using the constant current in the initial state of charging and then switching to constant voltage in the later stages of charging, when the battery reaches the set charge level.
Constant Voltage Mode (CV Mode): In this mode, the charging voltage applied at the battery terminals is maintained constant regardless of the battery charging current. Let’s examine these charging modes within the context of EV charging.
Charging voltage = OCV + (R I x Battery charging current limit) Here, R I is considered as 0.2 Ohm. Observing the below picture, it becomes evident that the DC power source regulates its charging voltage in accordance with the charging current limit.
Importantly, the DC power source ensures that it does not exceed the maximum battery voltage limit during this adjustment. The relationship between the charging voltage and the battery charging current limit can be expressed by the formula: Charging voltage = OCV + (R I x Battery charging current limit) Here, R I is considered as 0.2 Ohm.
Generally, the CV charging method is efficient for speedy charging, but it damages the battery capacity. The negative effect is caused by an increased charging current at a low battery SOC (at the beginning of the charging process), where the current value is significantly higher than the nominal battery current.
Understanding The Battery Charging Modes: Constant Current and Constant Voltage Modes Charging is the process of replenishing the battery energy in a controlled manner. To charge a battery, a DC power source with a voltage higher than the battery, along with a current regulation mechanism, is required.