The principle of the mobile power supply is simple. When an external power supply can be found, the built-in battery is charged in advance, that is, input electric energy, and pre-stored in the form of chemical energy. When needed, the battery provides energy and generates electric energy, which is converted by voltage The device (DC-DC converter) reaches the required voltage, and the output terminal (usually a USB interface) outputs and supplies the required equipment to provide power for charging or other purposes.
