Method and apparatus for diagnosing low voltage of secondary battery cell
The present invention relates to a method and an apparatus for diagnosing low voltage of a secondary battery cell. The method for diagnosing low voltage of a secondary battery cell according to an embodiment of the present invention includes pre-aging a battery cell, charging the battery cell according to a preset charging condition, measuring a parameter for determining low voltage failure of the battery cell, comparing the measured parameter with a reference parameter, and performing formation when the battery cell is determined to be normal.
1. A method for diagnosing low voltage failure of a secondary battery cell, the method comprising:
pre-aging a battery cell;
charging the battery cell to have a preset voltage according to a preset charging condition, wherein the preset voltage is set to a voltage of which a voltage change rate with respect to a state of charge (SOC) is greater than or equal to a preset reference value;
measuring a parameter for determining the low voltage failure of the battery cell;
comparing the measured parameter with a reference parameter to determine whether the battery cell is normal; and
subjecting the pre-aged battery cell to a subsequent charging under a predetermined voltage condition when the battery cell is determined to be normal, wherein the subsequent charging is an initial charging of a formation process.
2. The method of claim 1 , wherein the parameter is a charging duration from when the charging is started to when the battery cell reaches the preset voltage.
3. The method of claim 2 , wherein the charging duration is either a charging duration in a constant current mode, or a charging duration in a constant current charging interval of a constant current-constant voltage mode.
4. The method of claim 1 , wherein the parameter is a cumulative current amount accumulated from when the charging is started to when the battery cell reaches the preset voltage.
5. The method of claim 4 , wherein the cumulative current amount is measured in a constant current mode.
6. The method of claim 1 , wherein the parameter is a cumulative current amount accumulated from when the charging is started to when the battery cell reaches the preset voltage and a preset current.
7. The method of claim 6 , wherein the cumulative current amount is measured either in a constant current-constant voltage mode or in a constant current charging interval of the constant current-constant voltage mode.
8. The method of claim 1 , wherein the parameter is an amount of voltage drop of the battery cell from when the battery cell has reached the preset voltage and self-discharge is then started to a preset time.
9. The method of claim 1 , wherein the reference parameter is set differently depending on a type of the battery cell.
10. An apparatus for diagnosing low voltage failure of a secondary battery cell, the apparatus comprising:
a charging unit configured to charge a battery cell to have a preset voltage according to a preset charging condition, after a pre-aging process and before subjecting the pre-aged battery cell to a subsequent charging under a predetermined voltage condition, wherein the preset voltage is set to a voltage of which a voltage change rate with respect to a state of charge (SOC) is greater than or equal to a preset reference value, and wherein the subsequent charging is an initial charging of a formation process;
a measurement unit configured to measure a parameter for determining the low voltage failure of the battery cell; and
a control unit configured to compare the measured parameter with a reference parameter and determine the low voltage failure of the battery cell on the basis of a comparison result.
11. The apparatus of claim 10 , wherein the measurement unit measures, as the parameter, a charging duration from when the charging is started to when the battery cell reaches the preset voltage.
12. The apparatus of claim 11 , wherein the charging duration is measured either in a constant current mode or in a constant current charging interval of a constant current-constant voltage mode.
13. The apparatus of claim 10 , wherein the measurement unit measures, as the parameter, a cumulative current amount accumulated from when the charging is started to when the battery cell reaches the preset voltage.
14. The apparatus of claim 13 , wherein the cumulative current amount is measured in a constant current mode.
15. The apparatus of claim 10 , wherein the measurement unit measures, as the parameter, a cumulative current amount accumulated from when the charging is started to when the battery cell reaches the preset voltage and a preset current.
16. The apparatus of claim 15 , wherein the cumulative current amount is measured either in a constant current-constant voltage mode or in a constant current charging interval of the constant current-constant voltage mode.
17. The apparatus of claim 10 , wherein the measurement unit measures, as the parameter, an amount of voltage drop of the battery cell from when the battery cell has reached the preset voltage and self-discharge is then started to a preset time.
18. The apparatus of claim 10 , wherein the reference parameter is set differently depending on a type of the battery cell.