## 3 Results and Discussion  
### Battery Endurance  
The main characteristic of ESCTM architecture is the extended working life without changing batteries. This main power derives both from the speeded-up tests in the lab and from the calculations that are summarized below. For AgriLogger, AA Duracell Plus battery was found to be the best option in the market due to its strong characteristics, with a high voltage of 1.5 V, a high capacity of 2000 mAh and a very low self-discharge of 0.5% per month (Table 1).  
AgriLogger sensor was made in a way that each device inside the whole structure requires a negligible amount of power for each operating mode, the highest consumption is conducted by the data logger block that needs 0.1 uA for the sleep mode, 400 uA for uploading and 400 uA for sampling. The minimum consumption among the inner devices is drained by the wake-up circuit that demands 0.8 uA for each operating mode (Table 2). Further, ESC power consumptions are declared in Table 2, where the energy request of each block of the architecture is listed for the provided operating modes.  
Data reported in Tables 1 and 2 allow the calculation of device life, without changing batteries, in the conditions shown in Table 3. The power consumption is given knowing that data upload is done once each week. The overall consumption of current during the whole week is calculated by considering a constant sink of sleep current, plus the amount requested during the sampling phase, plus the current needed during the upload of collected data made once in a week. By a simple calculation we can estimate that the life of the device is longer than 10 years (532 mAh requested for that, Table 3). Therefore, the true limit is the quality of battery. Duracell, as a standard AA battery for instance, assures a limited self-discharge (0.5% per month) which should assure a battery life of more than 16 years. However, the expiration date marked on the products is always less than 10 years. In any case we consider that a duration of 5 years for this ESCTM device is enough for all the foreseeable applications.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{3}{c}{**AA Duracell Plus Battery Specification**} \\ \hline
**Parameter** & **Value** & **Conditions** \\ \hline Voltage & 1.5 V & 1A load \\ Capacity & 2.000 mAh & 10 m A load \\ Self-Discharge & 0.5\% Per month & 20 °C \\ \hline \hline \end{tabular}
\end{table}
Table 1: Standard Battery characteristics with the appropriate condition associated with each parameter value.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Device Elements**} & \multicolumn{3}{c}{**Operating Mode**} \\ \cline{2-4}  & **Sleep** & **Upload** & **Sampling** \\ \hline Microcomputer & 2.3 uA & 7.8 mA & 2.0 mA \\ Data logger & 0.1 uA & 400 uA & 400 uA \\ Real-time clock & 1.2 uA & 1.2 uA & 400 uA \\ Wake-up circuit & 0.8 uA & 0.8 uA & 0.8 uA \\ Power module & 0.0 uA & 100 uA & 0.0 uA \\ Transducer module & 60 nA & 150 uA & 150 uA \\ Cumulative current & 4.5 uA & 9.65 mA & 2.95 mA \\ \hline \hline \end{tabular}
\end{table}
Table 2: ESC different structures with the power consumption of each device according to the operating mode in action.