SECONDARY BATTERY CHARGING DEVICE, METHOD OF CHARGING IN SECONDARY BATTERY CHARGING DEVICE, PHOTOVOLTAIC GENERATOR, METHOD OF POWER GENERATION IN PHOTOVOLTAIC GENERATOR, PHOTOVOLTAIC-CHARGED SECONDARY BATTERY SYSTEM, ELECTRONIC DEVICE, AND ELECTRICAL VEHICLE

摘要

A battery charging device includes a battery pack including a plurality of battery cells connected in series, and a control unit. The control unit is configured to change a series connection of the battery cells in response to a variation in output voltage of a solar battery.