Apparatus for preventing deterioration of lithium secondary battery

摘要

When a battery with series-connected lithium secondary cells is charged to a high voltage, the capacity of the battery is prevented from being irreversibly deteriorated. If a battery current detected by a current sensor is small and a battery voltage detected by a voltage sensor is of a level (4.0 V) higher than a rated voltage (3.6 V) of each of the lithium secondary cells, then a switch is closed to connect a resistor to the battery thereby to forcibly discharge the battery. The voltage across the battery is now lowered to prevent the battery from being left to stand at a high voltage, and hence the capacity of the battery is prevented from being irreversibly deteriorated.