Typically, you charge lithium batteries by applying the CC-CV scheme. CC-CV stands for Constant Current - Constant Voltage. It denotes a charging curve where the maximum allowed charging current is applied to the battery as long as the cell voltage is below its maximum value, for example, 4.2 Volts.
This target charge current is relative to the battery capacity ("C"). For standard Li-ion or Li-polymer batteries, chargers often target 0.5C charge current. In other words, if the battery is rated at 500 mA-h, the target current is 250 mA. It is not unusual to charge at 1C (500mA), but this compromises the battery's capacity over time.
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. This point is commonly referred to as the “charging cut-off current.” II. Key Parameters in Lithium-ion Battery Charging
Overall, it takes 3426 s (57.1 min), which is theoretically the fastest charging time without lithium deposition, to fully charge the battery. This result is successful as it is able to support the optimal charge current theory presented previously, providing a general principle for fast charging of lithium ion battery.
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.
Typically, PMICs charge LiPo and Lithium-Ion batteries using the CC-CV method. The battery gets charged with a constant current until the cell reaches its maximum voltage. From then on, the charger gradually decreases the charge current until the battery is fully charged. Modern charge ICs apply a few more steps to the process to increase safety.