The SuperXcap Mini 100 mF supercapacitor from OptiXtal Inc., Philadelphia, PA, offers a max. voltage of 2.7 V, max. current of 25 mA, and an 8 by 11 by 0.9 mm package and weighs 0.08 g. Leakage current is as low as 1 µA, ESR is 3 ohms, and discharge during periods of nonuse is low. The supercapacitors can be stacked to function in series or parallel to achieve the desired power specs. Once operational, the supercapacitor will recharge to its maximum voltage within seconds.