Battery pack and method of calculating deterioration level thereof

1. A battery pack, comprising:

at least one battery;

a switch section which turns on and off charging to the battery;

a measurement section which measures an open circuit voltage of the battery; and

a deterioration level calculation section which calculates the deterioration level of the battery based on the open circuit voltage measured by the measurement section after the switch section has repeatedly turned on and off the charging 10 times or more.

2. The battery pack as set forth in claim 1 , wherein the deterioration level calculation section calculates the deterioration level of the battery based on the open circuit voltage measured by the measurement section when a relative capacity of the battery is less than 70%.

3. The battery pack as set forth in claim 1 , wherein the switch section turns on and off the charging to the battery at intervals of one second or less.

4. A method of calculating a deterioration level, comprising the steps of:

after repeatedly turning on and off charging to at least one battery 10 times or more, measuring an open circuit voltage of the battery; and

calculating the deterioration level of the battery based on the open circuit voltage.

5. The method as set forth in claim 4 , wherein the deterioration level of the battery is calculated when a relative capacity of the battery is less than 70%.

6. The method as set forth in claim 4 , wherein the switch section turns on and off the charging to the battery at intervals of one second or less.