**3. Experimental Setup**

To verify the viability for field applications, the ability of long-term stable electric power generation in a real outdoor environment is a key issue. The experimental test was performed over half a year, beginning in winter and ending in summer, thus covering a variety of weather conditions with wide temperature and humidity variations. From the test, the degradation of components was assessed, and the controls, the fueling, and the maintenance strategies was further refined.

Figure 7a depicts the experimental environment and instrument configuration. The power station was placed in a small outdoor rain-proof cabinet on the roof of a building to simulate an actual field environment. A supervising personal computer was placed indoors for remote status check and data logging. Figure 7b shows the inside of the cabinet where the power station was placed in the test and the dummy load acting as its power demand. Throughout the test, supervising the system for debugging as well as validation purposes, the data recorded are the voltage, current, temperature of the stack modules, the Li-ion battery, the outdoor ambient, and the inside of the cabinet. The performance data were accumulated to one sample per minute for analysis.

**Figure 7.** DMFC power station experiment setup. (**a**) Outside view; (**b**) inside view.

To test the power station to its full capacity, with 4 stack modules installed, the power generating capability is 3 to 4 W. To guarantee continuous electricity generation at full power for shortening test time, a 10 W thermoelectric cooler was selected as the dummy load. Therefore, *PLoad* was set to 10 W and *DLoad* was set to 1 in the power balance Equation (2), and the battery voltage varied between 3.5 V to 3.7 V due to the EMS over-drainage protection.
