A well designed Lithium-ion charger uses two stages to charge Lithium-ion batteries, which also includes those that are commonly called Li-Pos. During the first stage, the battery, or each battery of a resultant battery, is charged at a constant current (CC) until the battery reaches a predetermined charge termination voltage. That voltage depends on the type of Lithium-ion battery being charged. We'll just use batteries with a charge termination voltage of 4.2V to keep it simple. After reaching 4.2V per battery (constant voltage or CV) the current is then decreased to a predetermined value. Once that low, predetermined current value is reached, the charger then stops the charge process. The charger also has a circuit in it that prevents the battery from discharging back into the charger. Once the charger has stopped and the battery is removed from the charger, given several hours, each nominal 3.6V or 3.7V battery with a 4.2V charge termination voltage will settle to about 4.15V per battery or possibly a slight bit higher, or possibly lower. Once several days have passed, the battery will begin a self-discharge. Lithium based batteries need special care and should not be left for long periods in a fully charged or fully discharged state, as it significantly decreases their capacity. Also, if left fully discharged, the voltage can, over significant time, drop under the minimum voltage and may cause a short circuit problem inside the battery itself and the battery has been permanently damaged. When placed on a charger, it could heat up rapidly causing an unwanted event. |