I built a small weather station (like everyone else)
-D1 Mini (deepsleep)
-SI1145 UV sensor
-TP4050 charge controller
-Single cell LiPo harvested from a laptop battery
-6V solar panel
-Latching charge circuit, this circuit, once it gets a high signal from the 8266 uses current from the solar panel to hold it high till night time regardless if the high battery voltage has been met and the input turns low. The TP4050 protects from over charge.
The north country where I will return to doesn’t have tones of sunshine therefore I have oversized my solar panels and making use of a latching charge circuit. So every cycle the system checks if the battery is below 3.5V (that is not dead but gives me time to get through the night or till there is some sunshine) it changes the charge state to HIGH, also every cycle it checks if the charge state is high or low and triggers D7 accordingly.
If anyone is interested in the latching circuit let me know and I can post it here.