Do you mean to put cell phone lithium batteries on solar panels? Don't, it can't be achieved, it is a little dangerous to use the solar panel to charge the mobile phone battery directly, and use the mobile phone battery as an energy reserve, but there is no 5V output boost function, the same can not charge the mobile phone.
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You can't use solar panels to directly charge products such as mobile phones. The output voltage of the charger of mobile phone and other products is required to be about 5v, and the output voltage of the solar panel is not fixed, high and low, when greater than 5.5v or higher, it is easy to cause permanent damage to mobile phone and other products, and the output voltage must be controlled between 4.5V and 5.5v through the conversion circuit.
The built-in battery is to make the output more stable, but the premise must be configured with a safe and effective protection circuit and voltage conversion circuit.
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If the input power data matches, it can be charged, and the battery can be charged. It doesn't matter if you are solar, hydro or thermal