Precautions and Charging Principle for
18650 Lithium Battery Charging.
Firstly, charging
The safe working voltage range of lithium batteries is 2.8-4.2V. If the voltage is lower or higher than this range, the lithium ions in the battery become very unstable and even cause accidents. To ensure that the battery is within a safe range, a specialized charger is required. Although lithium batteries have protective boards, it is advisable to unplug the charger as much as possible after fully charging.
Secondly, activation
Before the lithium battery charger starts charging, it will supply a small current to the battery and simultaneously detect changes in battery voltage, gradually increasing the current until it reaches the set value. This process can be seen as an activation or test charging.
Thirdly, constant current and variable voltage charging
The charger charges the battery with a constant current, and as the battery voltage increases, the charger also increases the charging voltage to accelerate the charging speed.
Fourth, variable current constant voltage charging
When the battery reaches the cut-off voltage of 4.2V, it is only about 70% charged (not fully charged). At this point, the charger continues to charge the battery with a constant voltage and gradually decreasing current until the value is less than 0.1A. Charging is stopped only when the battery voltage continues to rise.
