More Battery Testing - Solar!

I wanted to post my very unscientific battery testing results, in the hopes it helps someone. I bought a small solar panel / charging board / 2500 mAh battery from Adafruit, and I wanted to see how long it would last if I were popping online / offline every minute to post some data. I’m sure this panel / battery is way bigger than I need, and my duty cycle is way too frequent. The core could easily be slept way more often, and I could adjust the duty cycle based on the battery level indicator / charge indicators from the battery charger board.

Parts list:

My question was, assuming a fully charged battery and no sun, how long could the core last in this mode? What duty cycle would last indefinitely given some small amount of daytime sun?

Here’s my setup with the solar panel:

Here’s my setup after it was fully charged, with the counter, one tick every 2 seconds, the core sleeping 75% of the time, and connecting to wifi 25% of the time, leds on, etc. Here’s my test code -

The final result was 62399 ticks, or about 124798 (lets assume 1% error, so +/- 1247.98 seconds), gives us a life of about 34 hours without any sun. The solar panel is rated to generate about 530mAh in full sun, I should only need a few hours of sunlight each day to break even, and any extra is bonus?

My next plan is to hook up a USB charging board to the battery as well, so I can charge my phone when I go outside to check on my core. :slight_smile:



I’ve been thinking about playing with something like this. I have an assortment of small solar panels I picked up at Fry’s on a whim last year. And I also have a small LiPo battery, a LiPo charging board, and various boost boards. So I figure solar -> boost -> charger -> battery should get me going.

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