I have Nest thermostat model 1.4. Which is just a year old. There are several months within the year where where we don’t need either heat or cooling. Currently the voltage reading is 3.16 although battery status states ok. The system is currently offline but since we are not physically there, I cannot do any trouble shooting to get it back online. My question however is does the system have to be running in order to keep the internal battery above the recommended 3.6 voltage? I was thinking that I need to verify that a C wire was part of the installation but does that even make a difference if the system goes for long periods without running? Maybe this thermometer is too smart for my needs. Anybody else have this question or have insight about internal battery voltage?