US Patent 10439419 Adaptive battery charging method and system

A method of charging a second battery in an electronic smoking device from a first battery in a charging device is provided, including: comparing an output voltage of the first battery with a threshold voltage; and when the output voltage is equal to or greater than the threshold voltage, charging the second battery using a first current; and when the output voltage is less than the threshold voltage, reducing the first current until the output voltage is equal to or greater than a second threshold voltage. A charging device is also provided, including control circuitry configured to control charging of the secondary battery.