Quick question, I am not very good with my electrical circuit terminology so I'm not sure what to call what I'm trying to do. When I try to Google "How to switch power supplies" I got inundated with results on switching power supplies, go figure.
I have a RPi that is powered via a car charger. (I found a car charger cable thing, the "female end if you will" at a garage sale, so I have that hooked to my power source!) The female car port… thing… is powered with 12 DC volts via 8 double A batteries in a battery pack. The car charger then powers the RPi. Runs quite a long time for what I do with it! However, I'd like to extend the running life of this.
My idea was to somehow have two alternative power supplies to the RPi charger, a battery pack, and solar panels! I picked up the panels to provide what I need. What I would like to achieve, is the solar panels and battery pack somehow hooked up through some sort of "switcher" if you will. I feel like this could be done with a voltage regulator and a transistor, just not sure how!
Anyways, I would like the solar panel to provide the power to the RPi when it is producing the required 12 volts or so, and then when there isn't good light and it stop producing the need voltage, the "switch" flips the charger over to the battery pack for power, until the panels can produce the 12 volts again, in which case it flips back over to the panel for the supply!
Best Answer
Connect a relay to the solar panel. When there is enough voltage, the relay will flip and power will be provided by the panel.
As said above, regulate the voltage to 5V before it enters RPi but it seems that you are already doing that.