Right now the hot board for low power nodes is the RAK wisblock based setup tinyurl.com/c7dhn2a5 . Runs the nrf52 chip which is super low power - i'm on an 1100 mah battery and even without the panel it was using only 10-15% per day.

WisBlock Meshtastic Starter Kit | The Basic RAK4631 Meshtastic Kit for LoRa

Join the LoRa Meshtastic network with the Meshtastic Starter Kit. Includes WisBlock Base board & the RAK4631 WisBlock Core module flashed with Meshtastic firmware.

One more follow up question: how were you able to reflash the board with new firmware? I just got some parts today and I’m having a hell of a time flashing a new boot loader onto the 4631 module. It refuses to go into DFU mode.

Excellent, thanks!