Wiring reference for solar lipo charger (with battery backup) powering Adafruit Trinket and FONA which posts battery voltage and other parameters to a ThingSpeak website located here: https://thingspeak.com/channels/62784

The installed unit posts battery voltage, analog response for rain presence, and analog repsonse for soil moisture (on/off) from a remote location on the San Pedro River watershed in Arizona to a ThingSpeak website using a FONA breakout (cellular service). The circuit is powered from lipo battery and solar power for charging. Voltage is analogous to what most sensors report to a microcontroller pin, so code for battery voltage reporting can be replaced accordingly. The design shared on this site is for temperature and humidity data collection.