A general approach for the design and construction of Unmanned Vehicles (UV) is presented in this paper, along with experimental data of a ground UV power consumption. We will focus on monitoring or sensing UV for distant geographical areas, inaccessible or with temporary hazardous conditions (e.g. under fire or flood). Since UV must be autonomous in situations and in periods of times not necessarily predictable, we have considered the control of power supply as an essential subsystem. We have built a very low cost prototype with emphasis on autonomy and we have measured the power supply costs of the different subsystems. Measurements will be important for the in-production UV as well as for reference values in future designs, including specific improvements. The complete system is built with two UV for increasing the total area coverage of the system. One of the UV is specifically dedicated to monitorization/sensing, and in this particular example it includes a camera. The remaining vehicle is dedicated to the retransmission of control and data (mostly pictures, in this example) to the system base. The current prototype of the complete system then consists of a base of operations and two UV (small cars).