Battery CV refers to Constant Voltage charging, a stage in battery charging where the voltage is held constant while the current decreases.
Understanding Constant Voltage (CV) Charging
Constant Voltage (CV) charging is a crucial part of a typical lithium-ion battery charging cycle, especially when used in conjunction with constant current (CC) charging. According to the provided reference, the charging process usually goes like this:
- Constant Current (CC) Charging: The battery is charged with a constant current until it reaches a specific voltage limit. For example, as the reference describes, the Battery CC-CV block performs constant-current (CC) charging until it reaches the limit cell voltage of 4.1 V specified in the Maximum cell voltage (V) parameter.
- Constant Voltage (CV) Charging: Once the voltage limit is reached, the charger switches to CV mode. In this mode, the voltage is held constant at the limit (e.g., 4.1 V), and the current gradually decreases as the battery approaches full charge. The reference mentions that the block charges the battery with a constant-voltage (CV) profile until the module SOC reaches 90%.
Why Use CV Charging?
- Prevents Overcharging: By holding the voltage constant and allowing the current to taper off, CV charging prevents overcharging and potential damage to the battery.
- Optimizes Battery Life: It helps extend battery life by carefully controlling the charging process.
Example
Let's consider a lithium-ion battery charging scenario:
- The charger applies a constant current of 1A until the battery voltage reaches 4.2V (CC phase).
- The charger then maintains a constant voltage of 4.2V. The current starts to decrease, going from 1A to, say, 0.5A, then 0.2A, and so on (CV phase).
- Charging stops when the current drops to a very low level, indicating that the battery is nearly fully charged.
