It’s time to start solar test number 4, the last test before installing a power management Arduino. This time I am starting out at sunrise with a fully charged set of four AA NiMh batteries and the Pi updating the database via the web service at Mission Control.
The last test lasted 30 hours, which was not too bad, but it did not make it through the second night, I think if I can make it through the second night, I can make it for quite some time.
So what’s different? I am using three 1N5817 Schottky diodes to keep the energy from going from the batteries to the solar when the solar is not producing enough power. I have also learned that Schottky diodes allow more energy through them. The less voltage drops, the better. Previously the 1N4148 diodes were losing 0.6 volts.
For reference, my solar cells are rated at 5v and 500ma. I have put 3 in parallel to charge the four AA 2450 mah batteries.
On a side note, I tried a single 18650 battery with the Seeed Studio Lipi Raider Pro and could get 13 hours without solar attached. The jury is still out on this solution.