Deterioration state computation method and deterioration state computation device

1. A deterioration-state calculation method for calculating a deterioration state of a battery by using a processor for managing a state of the battery, comprising:

detecting current of the battery and voltage of the battery by using a sensor;

calculating a state of charge of the battery based on a detected value of the sensor;

calculating a first deterioration state of the battery for each predetermined period based on an elapsed time from the start time of using the battery and an amount of charge-discharge of the battery;

calculating a second deterioration state of the battery based on a change amount in the state of charge of the battery and a change amount of current of the battery;

executing calculation step for calculating the second deterioration state for a plurality of times within the predetermined period;

calculating reliability of calculation of the second deterioration state for each of a plurality of the second deterioration states based on the detected value;

calculating a correction value of the deterioration state based on the second deterioration state with the reliability of the predetermined reliability or higher; and

calculating the deterioration state by correcting the first deterioration state by the correction value.

2. The deterioration-state calculation method according to claim 1 , wherein

the correction value is calculated by adding weighting that corresponds to the level of reliability of the second deterioration state.

3. The deterioration-state calculation method according to claim 1 , wherein

the reliability increases as polarization voltage of the battery becomes smaller, average current of the battery becomes lower, or a change amount of the state of charge of the battery becomes smaller.

4. The deterioration-state calculation method according to claim 2 , wherein the weighting is increased as the reliability becomes high.

5. The deterioration state calculation method according to claim 1 , wherein as the elapsed time becomes longer, or as the amount of charge-discharge becomes greater, the first deterioration state becomes lower.

6. The deterioration-state calculation method according to claim 1 , wherein a number of calculation times of the calculation step of the second deterioration state is equal to or more than a predetermined number of times in the predetermined period.

7. The deterioration-state calculation method according to claim 1 , wherein

the second deterioration state with the reliability of the predetermined reliability or higher is calculated for a predetermined number of times or more in the predetermined period.

8. A deterioration-calculation system comprising:

a sensor for detecting current of a battery and voltage of the battery; and

a processor for managing a state of the battery, wherein

the processor

calculates a state of charge of the battery based on a detected value of the sensor;

calculates a first deterioration state of the battery for each predetermined period based on an elapsed time from the start of battery use and an amount of charge-discharge of the battery;

calculates a second deterioration state of the battery based on a change amount of a state of charge of the battery and a change amount of current of the battery;

executes calculation step for calculating the second deterioration state for a plurality of times within the predetermined period;

calculates reliability of the calculation of the second deterioration state for each of a plurality of the second deterioration states based on the detected value;

calculates a correction value of the deterioration state based on the second deterioration state with the reliability of the predetermined reliability or higher; and

calculates the deterioration state of the battery by correcting the first deterioration state by the correction value.