[Today’s run: rest day]
I have a complete working system now, running off of a battery. So I’ve put this meter in the circuit so as to measure the current requirement.
This shows about 120 milliamps (12 volts DC). The little board with the red LED is a DC-DC voltage converter to change the 12 VDC down to 5 VDC for the beaglebone. The 12 VDC is used directly for the weather station/ sensor unit.
I got online and found a web page to calculate the size of the battery and solar panel I need. For a battery I need something around 25 mAh, and for solar panel I need a 30 watt.
I have ordered the solar panel and I have a 17 mAh battery which will let me test the setup.
The only other piece missing is the charge controller. There is a web group for a DIY (do it yourself) charge controller using an Arduino (http://www.freechargecontroller.org). That seems like overkill to me. I could probably use a few of the unused ports on the beaglebone to run a charge controller. Or I could just buy a cheap charge controller to get things started. I guess it depends on how efficient I want to be. A cheap one will not be as efficient in moving the power to the battery. So I am still thinking about building this part too.
