Battery charging method and apparatus

• US 5,550,453 A
• Filed: 01/24/1994
• Issued: 08/27/1996
• Est. Priority Date: 01/24/1994
• Status: Expired due to Term

• Current Assignee: Motorola Mobility LLC (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Bohne, William C., Bergquist, Eric A.
• Primary Examiner(s): NAPPI, ROBERT E
• Application Number:
  US08/185,344
• Time in Patent Office: 946 Days
• Field of Search: 320/20, 320/22, 320/23, 320/31, 320/32, 320/39, 320/40, 320/35
• US Class Current: 320/148
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

In a method and apparatus for battery charging, a battery charger (20) charges a battery (11), preferably in a battery pack (10), by providing an initial battery charging current (I₁) and terminating the initial charging current at a time t₂ in response to a measured battery condition (for example, battery temperature rate of change; Delta T/Delta t) exceeding a limit. A battery parameter, preferably battery voltage, is measured at the time t₂ and stored as a limit (V_peak). After t₂, battery charging current is provided in accordance with a predetermined criteria and battery charging current is altered (to I₃ ; or to I₁) in response to comparing a measured battery parameter, preferably battery voltage, after t₂ to a threshold (V_peak ; or V_peak -Delta V) based on the stored limit (V_peak). Preferably, rapid battery charging is implemented in response to a comparison of a measured battery parameter, preferably battery voltage, after the time t₂ with respect to a threshold (V_peak -Delta V) determined in accordance with the stored limit (V_peak).

Claims

1. A method of charging a battery, said battery having a battery voltage, said method comprising the steps of:

providing an initial battery charge current to said battery;

measuring a rate of temperature rise of said battery;

measuring said battery voltage when said rate of temperature rise reaches a predetermined level to obtain a V_peak level;

after measuring said battery voltage, reducing said battery charge current substantially below that of said step of providing; and

increasing said battery charge current after said step of reducing according to a predetermined staircase waveform until said battery voltage reaches said V_peak level.

2. A method of charging a battery according to claim 1, further comprising the step of:

repeating said steps of providing, measuring a rate of temperature rise, measuring said battery voltage, and reducing, after said step of reducing if said battery voltage falls below a predetermined delta below said V_peak level.

3. A method of charging a battery according to claim 1, further comprising the step of:

applying a maintenance charge current to said battery after said step of increasing.

4. A method of charging a battery according to claim 1, wherein said step of increasing comprises incrementally stepping up said charge current level after a predetermined time interval to provide said staircase waveform.

5. Battery charging apparatus, comprising:

means for providing an initial fast charge current to a battery, said battery having a battery voltage and a temperature;

means for measuring a rate of temperature rise of said battery;

means for measuring said battery voltage when said rate of temperature rise reaches a predetermined level to obtain a V_peak level;

means for providing an increasing charge current according to a staircase waveform having an initial current level substantially lower than said initial fast charge current, and providing said increasing charge current while said battery voltage is below said V_peak level.