How to deal with 18650 batteries & solar panels?


I’ve read most everything out there on this, and still the experts disagree. I have these little TP4056 boards (both old & new (with protection)). The old ones are a wash.

But with the new ones, I still see articles mentioning disconnecting the charging circuit from the battery when charged. I’m trying to do things simply, and will be testing the viability of using several 18650’s in parallel against ultra-capacitors to power my simple back yard weather station with as small a solar panel under $10 as I can.

I understand the voltage issues with a 5v Nano, and though it is working (on wall power) with a Nano 5v, for the sake of the voltage of my capacitors and the 18650s, I need a 3.3v MCU to make the parts list shorter (and presumably lose less energy in voltage conversions.

With that context behind us, here is one way to word the question:

  1. Providing that I use either 18650s or With a “new” TP4056 board:

    …can I just hook it up (ancillary diodes & caps aside) as-is to a 3.3v android MCU?

  2. What about if using 5.5v 1.5F caps like these:


When I read that you can’t just leave the charging circuit (even though it has ‘protection’ plugged in all the time, it makes me wonder how on earth I can make a stand-along weather station out in the back yard!

I just want this sucker to run & recharge itself. I’ve spent a fortune on crappy weather sensors taking AA batteries that die every couple of months. While I may tear apart one I have with an anemometer in it and attach it to my arduino unit, I have no interest in powering those things… I’d rather do it from scratch, and monitor and graph voltage, current, performance all remotely via radio.

With this being the last hurdle (not breaking everything) to overcome, I’ve started spending a few cycles on how on earth to house the BME280 sensor so it can operate but not rust away… :slight_smile:

Your ‘Project Guidance’ is greatly appreciated.