In battery operated applications the device should be in sleep mode as much as possible. The Wireless M-Bus protocol was designed for battery operated meters, and will provide 15-20 years of battery lifetime. Also the RC232 modules can be configured to sleep mode with less than 1 uA current consumption, only woken up to do transmissions when needed. The Sigfox modules are also very low power and suitable for battery operated LPWAN applications. Mesh networks use router nodes to retransmit messages, and therefore need mains power.
Last Update: August 8, 2017