USB Power Pack with Dynamic Voltage Switching

The battery pack is designed with a USB connector that enables it to function both as a power source for mobile devices and as a rechargeable device when connected to a personal computer's USB port. This dual functionality allows the same device to serve multiple purposes: charging external devices via its power output terminal and being recharged itself via the USB connector, thereby resolving the contradiction between maintaining simple structure and achieving charging adaptability.

The battery pack incorporates a switching mechanism that dynamically reconfigures the battery cell connections between series and parallel arrangements. This allows the system to adapt its voltage output based on the connected device's requirements: series connection for higher voltage devices and parallel connection for lower voltage devices. The dynamic switching capability enables the battery pack to serve multiple voltage requirements while maintaining stable output during each configuration state.

The battery pack utilizes multiple individual battery cells (at least two cells) that can be independently arranged and configured. This segmentation allows for flexible capacity scaling - users can choose the number and arrangement of cells based on their specific needs. The modular cell structure enables optimization between capacity and weight by selecting appropriate cell configurations, thereby resolving the contradiction between extended duration of action and manageable weight for portability.