POWER SUPPLY DEVICE

摘要

PURPOSE: Present invention relates to a power source comprising a plurality of secondary batteries to improve reliability and to eliminate capacity imbalance between batteries. CONSTITUTION: The improvement of a power supply device, especially the one provided witha plurality of serially-connected secondary batteries and a charging and discharging control for preventing the deterioration of the batteries with increasing speed and fully extracting the capabilities of the batteries. The power supply device is provided with a controlling section having a function to stop charging when the charged capacity becomes larger than the set value during charging, and a function to change the original set value to a larger one when a variation in charged capacities of the secondary batteries which are being charged becomes larger than the original set value.