Battery pack and method of controlling the same
A battery pack and a method of controlling the same is disclosed. The battery pack determines a cell deviation after the battery pack is fully charged or over-discharged, and thus the battery pack can reduce the cell deviation by performing cell balancing.
1. A battery pack comprising;
a plurality of battery cells; and
a computer,
wherein the computer is configured to:
determine voltages of the plurality of battery cells when the battery cells are in an open circuit voltage (OCV) state after the plurality of battery cells are fully charged or over-discharged;
determine a battery cell having a lowest voltage of the plurality of battery cells;
compare a difference between the a voltage of the battery cell having the lowest voltage and each of the voltages of the other of the plurality of battery cells to a specified value; and
perform cell balancing on at least one of the other of the plurality of battery cells if the voltage of the at least one of the other of the plurality of battery cells is larger than the voltage of the battery cell having the lowest voltage by more than the specified value;
wherein the computer is configured to perform the cell balancing in a sleep mode.
2. The battery pack of claim 1 , wherein the OCV state is a state wherein a difference between a maximum value and a minimum value, from among the voltages of any one of the plurality of battery cells for a predetermined time, is less than a threshold value.
3. The battery pack of claim 1 , wherein the computer is configured to perform the cell balancing by time-divisionally performing the cell balancing on odd numbered battery cells from among the at least one of the other of the plurality of battery cells and the cell balancing on even numbered battery cells from among the at least one of the other of the plurality of battery cells.
4. The battery pack of claim 1 , wherein the computer is configured to determine a finishing condition of the cell balancing.
5. The battery pack of claim 4 , wherein the determining of the finishing condition of the cell balancing comprises determining whether a voltage of a battery cell having undergone the cell balancing reaches a first threshold value.
6. The battery pack of claim 4 , wherein the determining of the finishing condition of the cell balancing comprises determining whether a difference between the voltage of the battery cell having undergone the cell balancing and a minimum voltage of the plurality of battery cells is less than a second threshold value.
7. The battery pack of claim 1 , wherein the computer performs the cell balancing when temperatures of the plurality of battery cells are within a predetermined temperature range.
8. A method of controlling a battery pack comprising a plurality of battery cells and a computer, the method comprising:
determining whether the plurality of battery cells are fully charged or over-discharged;
measuring voltages of the battery cells in an open circuit voltage (OCV) state when the plurality of battery cells are fully charged or over-discharged;
determining a battery cell having a lowest voltage of the plurality of battery cells;
comparing a difference between a voltage of the battery cell having the lowest voltage and each of the voltages of the other of the plurality of battery cells to a specified value;
and
performing cell balancing on at least one of the other of the plurality of the battery cells if the voltage of the at least one of the other of the plurality of the battery cells is larger than the voltage of the battery cell having the lowest voltage by more than the specified value;
wherein the cell balancing is performed when the computer is in a sleep mode.
9. The method of claim 8 , further comprising determining a finishing condition of the cell balancing.
10. The method of claim 8 , wherein the OCV state is a state wherein a difference between a maximum value and a minimum value, from among the voltages of any one of the plurality of battery cells for a predetermined time, is less than a second threshold value.
11. The method of claim 8 , wherein the cell balancing is performed by time-divisionally performing the cell balancing on odd numbered battery cells from among the at least one of the other of the plurality of battery cells and the cell balancing on even numbered battery cells from among the at least one of the other of the plurality of battery cells.