“…These modules are energy demanding, and therefore the use of energy harvesters can only be used as a complement, but not as the primary power source. In this regard, many studies [ 2 , 3 , 17 , 62 , 65 , 73 , 84 , 86 , 87 , 89 , 91 , 98 , 99 , 101 , 114 , 115 , 116 , 119 , 131 , 144 , 145 , 147 , 162 ] used rechargeable batteries to power the systems. The most common declared battery lives were in the order of hours ( Figure 23 ) [ 2 , 17 , 62 , 69 , 101 , 115 , 119 ], although some studies did not even provide data on this point.…”