The battery cell will have most of its charge when the battery voltage reaches 4.1 V or 4.2 V. At this point, the current going into the battery gradually decreases. When the current drops below a datasheet value, charging should be terminated. C/10 and C/30 are common charge termination current limits.
C/10 and C/30 are common charge termination current limits. When the battery is fully charged, the battery should be disconnected from the charger. Leaving the battery connected to the charger will cause the battery to overcharge and will damage the battery. The 18650 is popular cylindrical lithium cell, with a capacity of 2500 mAh.
The charging process for Lithium ion, Lithium polymer, and Lithium iron phosphate cells is terminated when the charge current drops to 10%. The top charging voltage and the termination current vary slightly with the manufacturer. However, a charge timer should be included for safety. The charging cannot be terminated based on voltage.
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
The exact termination current isn't critical, but voltage is. Usually the goal is to charge as quickly as possible, which requires a slightly higher voltage to overcome internal resistance. Then charge termination is required to avoid over-charging.
Lower termination current will charge the battery closer to full capacity. However, setting it too low can impact charging duration. Good termination accuracy necessary to get the most out of your battery and deliver a consistent full capacity being restored. Charged 41-mAh battery at 40-mAfast charge current (1C).