Battery pack charging apparatus and method for constant current and constant voltage charging of multiple battery packs

• US 7,782,011 B2
• Filed: 08/18/2004
• Issued: 08/24/2010
• Est. Priority Date: 02/07/2002
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Nishida, Junji, Manabe, Shinya
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): PIGGUSH, AARON C
• Application Number:
  US10/920,810
• Publication Number:
  US 20050046386A1
• Time in Patent Office: 2,197 Days
• Field of Search: 320/152, 320/112, 320/124, 320/162, 429/61, 324/434
• US Class Current: 320/112
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters

Abstract

A charging apparatus for charging a plurality of detachable battery packs includes a charging device for charging the plurality of battery packs one after another. A monitoring device is included to monitor attachment of a battery pack. A memory is included to store attachment history data of a battery pack based upon a monitoring result. A switching device is included to switch from one of the battery packs to the next battery pack. A voltage detecting device is included to detect a voltage of the next battery pack before charging. A charging manner setting device is included to set any one of constant current charging and constant voltage charging in accordance with the detected voltage. A charge current detecting device is also included to detect a current during charging of the next battery pack.

Claims

1. A charging apparatus for charging a plurality of detachable battery packs one after another, said charging apparatus comprising:

a charging device configured to charge the plurality of battery packs one after another;

a switching device operative to switch from a first one of the battery packs to a next one of the battery packs;

a voltage detecting device configured to detect a voltage of the next battery pack before charging of the next battery commences;

a charging manner setting device configured to

(i) select constant current charging as a charging technique to start charging said next battery pack, if a voltage of the next battery pack detected before charging of said next battery pack commences is in a first range, and

(ii) select constant voltage charging as a charging technique to start charging said next battery pack, if a voltage of the next battery pack detected before charging of said next battery pack commences is in a second range;

and

a charge current detecting device configured to detect a current during charging of the next battery pack,

wherein the charging device is configured to start charging the next battery pack by using the charging technique selected by said charging manner setting device.

2. The charging apparatus according to claim 1, wherein

a preparatory charging process is performed to the next battery pack until the detected voltage grows up to a first voltage level, when a secondary battery is used and is in an over discharge condition,

wherein a constant current charging process is performed until the detected voltage grows up to a second voltage level when the detected voltage is higher than the first voltage level, said second voltage level suppressing segregation of metal in the battery, and

wherein a constant voltage charging process is performed until charge current flowing through the battery pack becomes less than a prescribed level after the voltage of the battery pack has reached the second voltage level.

3. The charging apparatus according to claim 2, wherein the voltage of said battery pack having completed to receive charging is detected if the another battery pack has not been attached, and charging to the battery pack is started from said constant current charging process if the detected voltage is lower than a third voltage level, said third voltage level representing necessity of charging again due to natural discharge.

4. The charging apparatus of claim 1, wherein when said voltage of the next battery pack detected by said voltage detecting device is below a first threshold voltage level, said charging device performs preparatory charging with a preparatory charging current that is less than a current of said constant current charging.

5. The charging apparatus of claim 4, wherein said preparatory charging is terminated after said voltage of the next battery pack is at or above said first threshold voltage level, and then said constant current charging is performed.

6. The charging apparatus of claim 5, wherein said constant current charging is terminated after said voltage of the next battery pack is at or above a second threshold voltage level which is higher than said first threshold voltage level, and then constant voltage charging is performed.

7. The charging apparatus of claim 6, wherein no charging of the next battery pack is performed if said voltage of the next battery pack is at or above a third threshold voltage level which is higher than said second threshold voltage level.

8. The charging apparatus of claim 7, wherein if said voltage of the next battery pack is at or above said third threshold voltage level and no charging of the next battery pack is performed, availability of another one of the plurality of battery packs for charging is determined.

9. The charging apparatus according to claim 1, wherein

when the voltage of the next battery pack detected by the voltage detecting device before the charging of said next battery pack is commenced is above a first voltage level and below a second voltage level, constant current charging process is performed, and

when the voltage of the next battery pack detected by the voltage detecting device before the charging of said next battery pack is commenced is above the second voltage level a constant voltage charging process is performed.

10. The charging apparatus according to claim 9, wherein said next battery pack is a lithium battery, and said second voltage level is a voltage level at and above which segregation of metal in the battery is suppressed.

11. The charging apparatus according to claim 1, wherein

when the voltage of the next battery pack detected by the voltage detecting device before the charging of said next battery pack is commenced is below a first voltage level, a preparatory charging process is performed,

when the voltage of the next battery pack detected by the voltage detecting device before the charging of said next battery pack is commenced is above the first voltage level and below a second voltage level, constant current charging process is performed, and

when the voltage of the next battery pack detected by the voltage detecting device before the charging of said next battery pack is commenced is above the second voltage level a constant voltage charging process is performed.

12. The charging apparatus according to claim 1, wherein said selection of the charging technique to start charging the next battery pack is made by said charging manner setting device before the start of charging of said next battery pack.

13. The charging apparatus according to claim 1, wherein the charging device will start charging the next battery pack using constant voltage charging and will not start charging the next battery pack using constant current charging, if the charging manner setting selects constant voltage charging as a charging technique to start charging said next battery pack.

14. The charging apparatus according to claim 1, wherein said first range is the range of values from said first threshold voltage level to below said second threshold voltage level, and

wherein said second range is the range of values at or above said second threshold voltage level.

15. A method for charging a plurality of detachable battery packs, said method comprising:

(a) switching from one of the battery packs to a next one of the battery packs,

wherein the battery packs are simultaneously physically connected to a charging device, by use of a battery switching means;

(b) detecting a voltage of the next battery pack before charging of the next battery pack commences;

(c) selecting, on the one hand, constant current charging as a charging technique to start charging the next battery pack, if the voltage of the next battery pack detected in (b) before charging of said next battery pack commences is in a first range, and selecting, on the other hand constant voltage charging as a charging technique to start charging said next battery pack, if the voltage of the next battery pack detected in (b) before charging of said next battery pack commences is in a second range;

(d) starting charging of the next battery pack by applying the charging technique selected in (c); and

(e) detecting a current during charging of the next battery pack.

16. The method of claim 15, further comprising:

comparing said voltage of the next battery pack to a first threshold voltage level; and

when said voltage of the next battery pack is below a first threshold voltage level, performing said preparatory charging with a preparatory charging current that is less than a current of said constant current charging.

17. The method of claim 16, further comprising:

comparing said voltage of the next battery pack to said first threshold voltage level, during said preparatory charging;

terminating said preparatory charging after said voltage of the next battery pack is at or above said first threshold voltage level; and

performing said constant current charging after said preparatory charging is terminated.

18. The method of claim 17, further comprising:

comparing said voltage of the next battery pack to a second threshold voltage level which is higher than said first threshold voltage level, during said constant current charging;

terminating said constant current charging after said voltage of the next battery pack is at or above said second threshold voltage level; and

performing said constant voltage charging after said constant current charging is terminated.

19. The method of claim 18, wherein no charging of the next battery pack is performed if said voltage of the next battery pack is at or above a third threshold voltage level which is higher than said second threshold voltage level.

20. The method of claim 19, further comprising determining availability of another one of the plurality of battery packs for charging, if said voltage of the next battery pack is at or above said third threshold voltage level and no charging of the next battery pack is performed.