It looks like we’re not getting enough sun light to charge the batteries in my weather station, so I had to built a simple LM317 based 3V supply that I could get into the battery compartment. This should allow me run a 12V supply to the remote station.
Tried to build in 3D to maximise space.. Heating won’t be a problem, the weather station draws 20mA for about 1sec every 30sec or so for the transmission, the rest of the time the draw is about 8mA. Here are a few photos of the build: