The present invention discloses systems and methods for adaptive fast-charging for mobile devices and devices having sporadic power-source connection. Methods include the steps of: firstly determining whether a supercapacitor of a device is charged; upon detecting the supercapacitor is charged, secondly determining whether a battery of the device is charged; and upon detecting the battery is not charged, firstly charging the battery from the supercapacitor. Preferably, the step of firstly determining includes whether the supercapacitor is partially charged, and the step of secondly determining includes whether the battery is partially charged. Preferably, the step of firstly charging is adaptively regulated to perform a task selected from the group consisting of: preserving a lifetime of the battery by controlling a current to the battery, and discharging the supercapacitor in order to charge the battery. Preferably, the discharging enables the supercapacitor to be subsequently recharged.