Method of charging a battery array

• US 8,436,588 B2
• Filed: 02/02/2012
• Issued: 05/07/2013
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Panasonic Energy Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Morina, Kenichi, Suzuki, Katsuhiro, Uenaka, Yoshiro, Kaino, Tomomi
• Primary Examiner(s): RAMADAN, RAMY O
• Application Number:
  US13/364,420
• Publication Number:
  US 20120126750A1
• Time in Patent Office: 460 Days
• Field of Search: None
• US Class Current: 320/153
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage

Abstract

The method of charging a battery array performs constant current, constant voltage charging of a battery array while detecting the voltage of each battery. The battery array is a plurality of series connected batteries. The charge method detects the voltage of each battery cell at a prescribed sampling rate. When the voltage of any battery cell exceeds a preset maximum specified voltage, charging power is reduced for constant current, constant voltage charging of the battery array.

Claims

1. A method of charging a battery array with charging power that performs constant current and constant voltage charging of a battery array, which is a plurality of series connected batteries, while detecting the voltage of each battery, the method predetermining the charging power using multiple setting values based on battery temperature regions being charged, the method comprising:

detecting a first battery temperature;

setting an initial value of the charging power that is determined from the first battery temperature and beginning charging the plurality of battery cells of the battery array with the charging power set as the initial value; and

renewing the value of the charging power with a second value of the charging power, the second value being one of the multiple setting values based on a second battery temperature detected during charging, and continuing charging the plurality of battery cells of the battery array with the second value of the charging power,

wherein the initial value of the charging power is a same value as one of the multiple setting values predetermined based on the battery temperature regions being charged, and

wherein, during charging, detecting a voltage of each of the plurality of battery cells of the battery array at a prescribed sampling rate; and

when a voltage of any battery cell of the battery array exceeds a maximum specified voltage, performing a constant current and constant voltage charging of all the plurality of battery cells of the battery array at a same reduced charging power that is determined from the multiple setting values predetermined based on the battery temperature regions being charged, when a voltage of any battery cell of the battery array is at or below the maximum specified voltage,

comparing the second value of the charging power that is determined from the second battery temperature during the battery array with the initial value of the charging power that is determined from the first battery temperature at a start of charging the battery, and

continuing charging of all the plurality of battery cells of the battery array with a same charging power, the same charging power being renewed to a lower value of charging among the second value of the charging power and the initial value of the charging power if the initial and second values are different from each other.

2. The method of claim 1, wherein the plurality of series connected batteries of the battery array are lithium ion rechargeable batteries.

3. The method of claim 1, wherein the voltage of each battery cell of the battery array is detected at a prescribed sampling rate, and when the voltage of any battery cell exceeds a preset maximum specified voltage, a charging voltage is reduced for performing constant current and constant voltage charging of the battery array.

4. The method of claim 3, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, a voltage for charging the battery array is reduced by a prescribed ratio.

5. The method of claim 3, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced, and a ratio for reducing the charging voltage is determined from a voltage difference between the maximum specified voltage and a voltage of a battery cell, and when the voltage difference is large, the ratio for reducing the charging voltage is made large.

6. The method of claim 3, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced, and a ratio for reducing the charging voltage is determined from an internal resistance of a battery cell that exceeded a maximum specified voltage, and when battery cell internal resistance is large, the ratio for reducing the charging voltage is made large.

7. The method of claim 3, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the voltage for charging the battery array is reduced to a battery voltage, which is a sum of the voltages of each battery cell.

8. The method of claim 1, wherein the maximum specified voltage is set in a range from 4.20V to 4.24V.

9. The method of claim 1, wherein the maximum specified voltage changes with battery temperature.

10. The method of claim 9, wherein a maximum specified voltage for battery charging in a low temperature region is set lower than a maximum specified voltage for battery charging in a standard temperature region.

11. The method of claim 10, wherein the maximum specified voltage in the low temperature region is set from 30 mV to 300 mV lower than the maximum specified voltage in the standard temperature region.

12. The method of claim 9, wherein a maximum specified voltage for battery charging in a high temperature region is set lower than a maximum specified voltage for battery charging in a standard temperature region.

13. The method of claim 9, wherein a maximum specified voltage in a high temperature region is set lower than a maximum specified voltage in a standard temperature region, and is set higher than the maximum specified voltage in a low temperature region.

14. The method of claim 13, wherein the maximum specified voltage in the high temperature region is set to make a voltage difference between the maximum specified voltage in the high temperature region and the maximum specified voltage in the standard temperature region 30% to 80% of a voltage difference between the maximum specified voltage in the low temperature region and the maximum specified voltage in the standard temperature region.

15. The method of claim 1, wherein the initial value of the charging power at the start of charging the battery array is set by two parameters of temperature and remaining capacity or temperature and voltage.

16. The method of claim 15,

wherein the voltage of each battery cell is detected at a prescribed sampling rate, when the voltage of any battery cell of the battery array exceeds a preset maximum specified voltage, a set current is reduced for performing constant current and constant voltage charging of the battery array, and

wherein the set current is controlled to elect from predetermined values that are preset depending on the parameters, the predetermined values including an initial value of the charging current at the start of charging the battery.

17. The method of claim 16, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced by a prescribed ratio.

18. The method of claim 16, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced, and a ratio for reducing the set current is determined from a voltage difference between the maximum specified voltage and a voltage of the battery cell, and when the voltage difference is large, the ratio for reducing the set current is made large.

19. The method of claim 16, wherein when the voltage of any battery cell of the battery array exceeds the maximum specified voltage, the set current for charging the battery array is reduced, and a ratio for reducing the set current is determined from an internal resistance of a battery cell that exceeded the maximum specified voltage, and when battery cell internal resistance is large, the ratio for reducing the set current is made large.

20. The method of claim 16, wherein the set current changes with battery temperature.

21. The method of claim 20, wherein reduction in set current is in accordance with multiple levels of a prescribed set current.