In the rise of the IoT era ambient-energy harvesting is expected to liberate networked embedded systems from the use of batteries. Several research efforts have already addressed in depth the perennial powering of embedded systems through energy harvesting, mainly focusing on WSNs. Super-capacitors offer a viable alternative for ambient-energy harvesting applications, demonstrating significant advantages and much longer operating lifetime over rechargeable batteries. This paper applies similar concepts to more powerful microprocessor-based unsupervised wireless mobile embedded systems that can be accessible anywhere over a short burst satellite connection. AITHALES is a power-autonomous batteryless M2M satellite tracking embedded system harvesting ambient solar, thermal and vibration energy and storing it in a super-capacitor which supplies uninterrupted power to the tracking unit. The system was developed in the context of a container tracking application for container operators to tackle the problem of container loss, but serves as a paradigm for autonomous outdoor monitoring systems required to operate uninterrupted under often harsh environmental conditions and without periodic user intervention. The paper concludes with a feasibility study of powering the system from multiple ambient energy sources (solar, thermal and vibrations) and proves that performance is adequate for completely unsupervised system operation.