Battery charging operation and a detection of a fully charged condition of the charged battery

• US 5,998,970 A
• Filed: 06/29/1998
• Issued: 12/07/1999
• Est. Priority Date: 07/04/1997
• Status: Expired due to Term

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Takano, Nobuhiro, Ishimaru, Kenrou
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): LUK, LAWRENCE W
• Application Number:
  US09/106,306
• Time in Patent Office: 526 Days
• Field of Search: 320/132, 320/148, 320/153, 320/130
• US Class Current: 320/132
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

A microcomputer performs a total of 100 sampling actions during a 1 sec sampling period for obtaining a plurality of battery voltage data V. In each sampling period, a minimum value υmin and a maximum value υmax are stored in a RAM 53. A peak value VMAX, used for detecting a peak battery voltage in the charging operation, is renewed by a largest data among the sampled minimum values υmin. A differenc ΔV between the peak value VMAX and the maximum value υmax is calculated the end of each sampling period. And, when the calculated difference ΔV exceeds a predetermined value, a judgement is made that the battery is fully charged.

Claims

1. A battery charging method comprising the steps of:

performing a plurality of sampling actions for obtaining a plurality of battery voltage data during a predetermined sampling period when a battery is charged;

storing a minimum value and a maximum value among said battery voltage data in each sampling period;

renewing a peak value by a largest data among the sampled minimum values;

obtaining a difference between said peak value and said maximum value at the end of each sampling period; and

making a judgement that the battery is fully charged when said obtained difference exceeds a predetermined value.

2. The battery charging method in accordance with claim 1, wherein said battery voltage data are in a digital form processible in a microcomputer.

3. The battery charging method in accordance with claim 2, wherein said predetermined value used in the judgement of the full-charge condition is a predetermined bit number.

4. The battery charging method in accordance with claim 1, further comprising a step of repetitively restarting said sampling period until the full-charge condition is detected.

5. A battery charging apparatus comprising:

charging means for charging a battery;

sampling means for performing a plurality of sampling actions for obtaining a plurality of battery voltage data during a predetermined sampling period when the battery is charged;

memory means for storing a minimum value and a maximum value among said battery voltage data in each sampling period;

peak detecting means for renewing a peak value by a largest data among the sampled minimum values;

decline detecting means for obtaining a difference between said peak value and said maximum value at the end of each sampling period; and

full-charge condition detecting means for making a judgement that the battery is fully charged when said obtained difference exceeds a predetermined value.

6. The battery charging apparatus in accordance with claim 5, wherein said battery voltage data obtained by said sampling means are in a digital form processible in a microcomputer.

7. The battery charging apparatus in accordance with claim 6, wherein said predetermined value used in said full-charge condition detecting means is a predetermined bit number.

8. The battery charging apparatus in accordance with claim 5, wherein said sampling means repetitively restarts said sampling period until the full-charge condition is detected.