An RF asset-tracking device that has an extended operational life, thus increasing the duration between battery replacement or maintenance. The asset-tracking device is provided with an electro-mechanical energy-harvesting device to supplement the battery. The energy-harvesting device provides additional power to augment the battery on a temporary basis, when the battery level is low, until the battery can be replaced. In one particular embodiment, the tracking device has a power management system, a battery power source and a battery monitor, and an electro-mechanical energy-harvesting device and a high capacity supercapacitor operably connected to the power management system.