Charge Voltage – The voltage that the battery is charged to when charged to full capacity. Charging schemes generally consist of a constant current charging until the battery voltage reaching the charge voltage, then constant voltage charging, allowing the charge current to taper until it is very small.
(Recommended) Charge Current – The ideal current at which the battery is initially charged (to roughly 70 percent SOC) under constant charging scheme before transitioning into constant voltage charging. (Maximum) Internal Resistance – The resistance within the battery, generally different for charging and discharging.
A high charging current from 15 percent to 80 percent SOC provides fast charging, butthe high current stresses the battery and can cause battery lattice collapse and pole breaking. The main challenge for CV charging is selecting a proper voltage value that will balance the charging speed, electrolyte decomposition, and capacity utilization.
Going below this voltage can damage the battery. Charging Stages: Lithium-ion battery charging involves four stages: trickle charging (low-voltage pre-charging), constant current charging, constant voltage charging, and charging termination. Charging Current: This parameter represents the current delivered to the battery during charging.
At this stage, the battery voltage remains relatively constant, while the charging current continues to decrease. Charging Termination: The charging process is considered complete when the charging current drops to a specific predetermined value, often around 5% of the initial charging current.
The constant voltage method keeps a constant voltage during the charging process. However, there is a gradual decrease in current as the battery charges. The charging process stops after this current reaches a certain level. This charging method is used in nickel-cadmium and lead-acid batteries. Figure 2. Constant voltage charging curve.