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I'm using an battery shield to recharge my battery. I want to use a solar panel, so I bought one (5V 240mA). I'm pretty sure, it won't recharge my battery fully, but that's not the point. I've assembled my board with my shield, soldered the solar panel together with an schottky-diode and put it on USB (since the shield allows charging via USB). All fine, I get some electric power in the sun - yeah!

But my Wemos D1 Mini only runs for say 2-3 minutes and than ... dead? Restarting works, but only lasts again 2-3 minutes. This only happens while the battery shield is charging via solar. I already tested using any USB charging (my computer) - this simply works.

Basically I rebuild the circuit like described on TheAustrian/Wemos-D1-Mini-BME280-Weather-Station but only one solar panel attached and using the Wemos D1 Mini Battery Shield instead of the TP4056.

Any hints what's going on? Why can't I run the board while charging via solar? Did I miss something?

Michael Hirschler
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The TP4056 Module will output a max of 4.2V which is less than the 5V the Wemos D1 Mini is expecting on its 5V connection (Assuming you have connected the circuit as shown in the Github guide). When the solar panel is charging it's likely that the TP4056 is causing a driving issue on the supply of the Wemos causing it to potentially Brownout .

I would not connect the solar panel to the Wemos like this, I would have it connected to the battery then the battery connected to a 5V Step Up Power Converter like shown below (This reduces efficiency but give the MCU a stable supply),

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My recommendation for the wiring,

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Sneaky Puffin
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