Battery considerations

[jazzmonger]

Lithium ion doesnt charge below freezing. LifePO4 batteries do diwn to -40F. So I use 2 single LifePO4 cells in parallel. After over 2500 cycles theyve dropped from 3.4v to 3.29v. So, really quite good.Time will tell on battery life, but I have a few tricks here that really make a huge difference in extending battry life. Im also planning on adding a camera solar charge panel as soon as the LifePO4 charge modules are available again from Adafruit.

https://www.adafruit.com/product/6091

This is key:
Default 3.7V nominal / 4.2V max battery chemistry/voltage for all modern 1-cell LiPoly or LiIon batteries. You can set this to 3.2V / 3.65V for LiFePO4 batteries by cutting the VS jumper on the front and soldering a jumper on the back

I also used this fast_connect: on flag in the wifi config. It helped the esp connect almost immediately upon wake up and prevents the esp from scanning all available networks. This further reduced power consumption.

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password
  fast_connect: on