Hi Johann and welcome.
I am not familiar with the Seeed boards, but have had some experience with other ESP32-S3 boards and charging from solar panel. It has been a frustrating trip, but more on that later.
Which of the XIAO boards did you get ? If Seeed Studio XIAO ESP32S3 (SKU: SS113991114) then I assume you soldered the battery onto the pads in the middle of the underside of the board. That is reasonable.
But then you mention connecting the Solar Charger with JST PH … did you connect the JST connector on the Solar Charger to the XIAO’s VUSB and GND pins ? Like Jane, I ask you to share a photo or diagram; this would help a lot to give the best advice.
Sorry it’s rather long, but this is my overview to provide context. What I have learnt is :
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Espressif promote their ESP32 as having very low power requirement.
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This is true of the ESP32 chips themselves - but early Development Boards were designed to be permanently connected to USB power, and so used cheaper components and designs with high quiescent current.
Engineers designing products which require long battery life would custom design their own circuit boards using components and software techniques to achieve low quiescent current. -
Recently we are seeing more ESP Dev Boards which connect a LiPo battery direct to the Dev Board, and have a lower quiescent current. The XIAO is one of these, which I now refer to as being “portable” because manufacturers seem to assume that they will be recharged from USB.
USB provides a nice steady 5V current. -
However a Solar panel does not provide a steady current. The two panels i have both regulate their output to 5V - but the current jumps up and down depending on clouds and shadows … and is not suitable for connecting to the ESP32’s 5V IN
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Your Solar Charger and other Solar Power Managers are designed for this (especially MPPT) … unfortunately all the Solar Power Managers and Chargers assume that their purpose is to supply steady power to the output pins, and use excess to charge the connected LiPo … and so they do not work properly without a LiPo battery to smooth out the fluctuations coming from the solar panel.
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So far I have found only 2 dev boards which are designed to charge from a solar panel - the DFRobot Firebeetle 2 ESP32-C6 and Firebeetle 2 ESP32-C5. They have MPTT built into the Firebeetle 2 dev board; and so I believe they are designed for “remote” operation where here is no handy USB charger. Unfortunately they don’t have the memory and processing power of an ESP32-S3, and because I have only just got a couple of these boards, I can’t comment from personal experience yet
But back to a bit more detail about section 5, which is where I (and I think you) are.
It seems that the Solar Charger you have, and other Solar Power Managers I have tried all require a battery. Effectively we have 3 options:
(a) Connect LiPo to the ESP32 devBoard and charge from USB instead of from solar; OR
(b) Connect LiPo to a Solar Power Manager and ignore the XIAO’s LiPo connector and battery voltage measurement; OR
(c) add a second battery to the Solar Charger so that it can feed steady power to the ESP32 board, which charges the battery connected to the ESP32 dev board. This is like having a UPS backing up a UPS.
The “portable” microcontrollers are a step towards “remote” microcontroller systems because they are made with low-power components; but they don’t allow us to remove the external solar power manager and external voltage measurement. This discussion could provide some more background.
The problem with the DFRobot Solar Charger for us is that it does not boost its output to 5V like other Solar Power Managers. Instead it provides only the battery’s voltage … which will vary from 4.2V fully charged down to about 2.6V when fully discharged … not suitable for running the XIAO, and probably not even suitable for giving to the XIAO’s VUSB
I should also point out that the DFRobot Solar Charger you have should be wired with the solar panel to its PWR IN screw connectors, the LiPo battery to its JST PH connector, and the VOUT screw connectors to the XIAO’s VBAT and GND.
If you connected the XIAO to the Solar Charger’s battery connector, that could be the reason you are not seeing the status LEDs.
A lot to dump on you, I know. Hopefully just showing the ‘big picture’, well as i see it. I hope i have not scared you off.
