Over 4 years on, and my node ran continuously sending 4 messages every 5 minutes.
It's 700mAh LiFePo4 battery voltage dropped from initial 3.45V to 3.24V, according to LiFePo4 voltge/SoC tables It's just under 40% left.
700*60% = 420mAh. 100 mAH per year. using library 2.40 and blob message I could cut usage to ~25mAh/year, not bad