Charging method of battery and battery charging system
A method of charging a battery and a battery charging system, which has a relatively high charging speed while having a relatively low level of battery deterioration. The charging method includes charging a battery cell with a first current in a first constant current mode; charging the battery cell with a first voltage in a first constant voltage mode; idling the charging of the battery cell for a first idle period (t); charging the battery cell with a second current different from the first current in a second constant current mode; and charging the battery cell with a second voltage different from the first voltage in a second constant voltage mode.
1. A method of charging a battery, the method comprising:
charging a battery cell with a first constant current in a first constant current mode;
charging the battery cell with a first constant voltage in a first constant voltage mode;
idling the charging of the battery cell for an idle period (t) after the charging the battery cell in the first constant voltage mode;
charging the battery cell with a second constant current different from the first constant current in a second constant current mode after the idling the charging of the battery cell; and
charging the battery cell with a second constant voltage that is higher than the first constant voltage in a second constant voltage mode.
2. The method of claim 1 , wherein the idle period (t) is in a range of about 1 ms to about 10 s.
3. The method of claim 1 , wherein the idle period (t) is about 1 to about 10 times a voltage stabilizing time (τ) of the battery cell.
4. The method of claim 3 , wherein the voltage stabilizing time (τ) of the battery cell is an amount of time taken to reduce a value A(t) of the following equation by 1/e:
A ( t )= A n e −t/τ
where A n is a value obtained by subtracting a stabilized battery cell voltage v n,0 from a battery cell voltage V n of an initial stage of the idle period (t), where n is a natural number and t is greater than 0.
5. The method of claim 1 , further comprising calculating a charge capacity of the battery cell, wherein the idle period (t) is proportional to the charge capacity of the battery cell.
6. The method of claim 1 , further comprising sensing a temperature of the battery cell, wherein the idle period (t) is inversely proportional to the temperature of the battery cell.
7. The method of claim 1 , further comprising:
determining whether or not a voltage of the battery cell reaches a first reference voltage by sensing the voltage of the battery cell while charging the battery cell with the first constant current in the first constant current mode; and
determining whether or not a current of the battery cell reaches a first reference current by sensing a charge current of the battery cell while charging the battery cell with the first constant voltage in the first constant voltage mode.
8. The method of claim 7 , wherein when the charge current of the battery cell reaches the first reference current, the idling is performed.
9. The method of claim 7 , further comprising:
determining whether or not a voltage of the battery cell reaches a second reference voltage by sensing the voltage of the battery cell while charging the battery cell with the second constant current in the second constant current mode; and
determining whether or not a charge current of the battery cell reaches a second reference current by sensing the charge current of the battery cell while charging the battery cell with the second constant voltage in the second constant voltage mode.
10. The method of claim 9 , wherein the second reference voltage is greater than the first reference voltage.
11. The method of claim 9 , wherein the second reference current is smaller than the first reference current.
12. The method of claim 1 ,
wherein the first constant voltage mode is immediately after the first constant current mode,
wherein the idle period is immediately after the first constant voltage mode,
wherein the second constant current mode is immediately after the idle period, and
wherein the second constant voltage mode is immediately after the second constant current mode.
13. A battery charging system comprising:
a battery pack comprising a battery cell, a voltage sensor configured to sense a voltage of the battery cell, and a current sensor configured to sense a charge current for charging the battery cell; and
a charging unit configured to charge the battery cell with a first constant current in a first constant current mode, charging the battery cell with a first constant voltage in a first constant voltage mode, idling the charging of the battery cell for an idle period (t) after the charging the battery cell in the first constant voltage mode, charging the battery cell with a second constant current different from the first constant current in a second constant current mode, and charging the battery cell with a second constant voltage that is higher than the first constant voltage in a second constant voltage mode after the idling the charging of the battery cell.
14. The battery charging system of claim 13 , wherein the idle period (t) is in a range of about 1 ms to about 10 s.
15. The battery charging system of claim 13 , wherein the idle period (t) is about 1 to about 10 times a voltage stabilizing time (τ) of the battery cell.
16. The battery charging system of claim 15 , wherein the voltage stabilizing time (τ) of the battery cell is a time taken to reduce a value A(t) of the following equation by lie:
A ( t )= A n e −t/τ
where A n is a value obtained by subtracting a stabilized battery cell voltage v n,0 from a battery cell voltage V n of an initial stage of the idle period (t), where n is a natural number and t is greater than 0.
17. The battery charging system of claim 13 , further comprising a calculation unit configured to calculate a charge capacity of the battery cell, wherein the idle period (t) of the charging unit is controlled to be proportional to the charge capacity of the battery cell.
18. The battery charging system of claim 13 , further comprising a temperature sensor configured to sense a temperature of the battery cell, wherein the idle period (t) of the charging unit is controlled to be inversely proportional to the temperature of the battery cell.
19. The battery charging system of claim 13 ,
wherein the first constant voltage mode is immediately after the first constant current mode,
wherein the idle period is immediately after the first constant voltage mode,
wherein the second constant current mode is immediately after the idle period, and
wherein the second constant voltage mode is immediately after the second constant current mode.
20. A method of charging a battery, the method comprising:
charging a battery cell with a first current in a first constant current mode;
charging the battery cell with a first voltage in a first constant voltage mode;
idling the charging of the battery cell for an idle period (t);
charging the battery cell with a second current different from the first current in a second constant current mode; and
charging the battery cell with a second voltage different from the first voltage in a second constant voltage mode,
wherein the idle period (t) is about 1 to about 10 times a voltage stabilizing time (τ) of the battery cell, and
wherein the voltage stabilizing time (τ) of the battery cell is an amount of time taken to reduce a value A(t) of the following equation by 1/e:
A ( t )= A n e −t/τ
where A n is a value obtained by subtracting a stabilized battery cell voltage v n,0 from a battery cell voltage V n of an initial stage of the idle period (t), where n is a natural number and t is greater than 0.