Wow! It's been 2 years since I've posted to my blog and the last ~24 months have certainly been eventful (both good and bad)!
Here i was posting about the new Raspberry Pico and for the last month or so I've been playing with it's new sibling, the Pico W. Unbelievable that they can pack all of that technology into a small package for $7.95CDN!
One of my hobbies is container gardening and I usually have the energy to plant the garden in the spring, but then my focus wanders and I'm intermittent on the daily watering part....grin. So the plan was to use a Raspberry Pi Zero W to pump the water I've captured in my rain barrels to the plants in the container garden, and to power it all with solar!
Well my 60Watt Solar panel could keep the pi zero w going from June to September, but as the days are getting shorter, I switched to 2 x 80W panels
Connected to my AGM Battery with the Solar Charge Controller mounted on top. Note the high quality waterproof container (plastic bag) that it is housed in (grin)! I'm planning on making a proper container and large stand for my 7 containers etc, but that is a next Spring project. The AGM (Gel Cell) battery is a 12V, 10.3AH which was recovered from an annual emergency lighting upgrade I did. The battery capacity wasn't enough to pass the lighting test, but it will work well for my garden experiments!
And a recycled container that used to hold wood screws is the new home for my power supply and pico w
I use a inexpensive switch mode power supply to step the ~13.8VDC from the battery down to the 5.1VDC originally for the Zero W and now the Pico W. I don't need the 250mA idle draw of the Zero W and am hoping that the ~20mA draw of the Pico will allow the solar panels to keep the battery charged through the winter...?
I take the voltage coming into the switch mode power supply and feed that to a 100k ohm, 10 turn (for ease of adjustment) potentiometer so that I can step the 11 - 15VDC that may be supplied down to the 3.3VDC max that the pico will measure on the ADC (Analogue to Digital Converter). The small green wires are the feed from the potentiometer to the analogue input of the pico. I've also soldered in a 250mA pico fuse inline just in case something goes wrong. All of that is hidden inside the bright orange duct tape that I've wrapped the power supply in so that the pico board cannot accidentally come in contact with the power supply board.
In another post I'll show the schematic and share the MicroPython code that I used to measure the voltage and then send it wirelessly to my mqtt broker so that I can display it via a Node Red gauge as well as graph the changes over the past 24 hours.
Thanks for viewing!
Robin
