The first
prototype used a battery box consisting of
2 LiPo cells (18650) in series to give an output of 7.4v.
This is then
reduced to 5.2 volts. Fitted into the battery box is a
charging pcb that will charge this
arrangement (7.4v)
from a standard USB port. This runs the weather
station for 3 hours continuous.
This unit is
also used to regulate the solar panel output to 12 volts or
5.2
volts.