@johann318929 your photo shows nothing connected to the Solar Charger’s PWR IN screw terminals. Your solar panel should be connected here.
If I plug a LiPo battery into the JST PH connector of my DFRobot Solar Charger (same model as you have) … neither LED lights up. The schematic shows both LEDs are powered from PWR IN … so you need to connect the solar panel to the PWR IN screw terminals, and to have sunshine on the solar panel for the Solar Charger to do anything.
At the other end, the VOUT is parallel with the BAT connector - so if you place a multimeter across the VOUT screw terminals you can measure the battery voltage even when there is no power coming from the solar panel.
It is a bit hard to tell from your photo, but I guess that you have your battery wired to both the BAT pads underneath the XIAO and to the Solar Charger’s BAT JST PH connector. Is this correct ?
If so, this matches with advice from a user on another forum, and which I have been using for a couple of weeks. Note that Jane and Robert have both expressed concerns, and I am not experienced with electronics, so please do not assume this is correct.
This diagram I made of my setup has an ESP32-S3 dev board instead of your XIAO ESP32-S3; and a DFRobot Solar Power Manager instead of the DFRobot Solar Charger. Your solar panel should be connected to the Solar Charger PWR IN screw terminals.
@Jane I looked at the schematic for the DFRobot Solar Charger and the VOUT and BAT are in parallel.
Furthermore another piece of the puzzle fell into place for me. This Solar Charger is the appropriate device to use with those dev boards with battery connectors because the VOUT is unregulated. LiPo plugs into the Solar Charger JST connector, and the charger’s VOUT is connected to the dev boards BAT JST connector. Voila, the dev board is able to read the battery voltage, and the Solar Charger is handling the solar panel. All the SPM’s charging options and the regulated 5V output are not actually required.
I doubt the dev board’s USB could be used to charge the LiPo - but the objective is to charge from solar panel remotely where there is no USB power … so not a problem.
