Method and apparatus for charging a battery using a threshold to cease charging

• US 7,449,862 B1
• Filed: 09/29/2006
• Issued: 11/11/2008
• Est. Priority Date: 09/29/2006
• Status: Expired due to Fees

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Patino, Joseph, Oglesby, Stephen J., Voor, Thomas E.
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US11/536,859
• Time in Patent Office: 774 Days
• Field of Search: 320/107, 320/110, 320/128, 320/134, 320/136, 320/160, 320/162
• US Class Current: 320/107
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A device (102) contains a battery (116) which is recharged under control of a charge controller (112). An external power supply (104) provides charging current and voltage (106). A linear regulator (110) regulates the raw voltage provided by the external power supply. The device (102) also contains a heat-generating sub-system (118). To prevent excess heat generation while charging the battery, the battery charging regime is altered from a conventional regime when the heat-generating sub-system is active. Once the battery voltage reaches a charge limit (208), charge current is ceased (210) until the battery voltage falls to a lower limit (212), at which time the charging current is recommenced.

Claims

1. A method of charging a battery attached to a mobile communication device after the battery has been charged to a charge voltage limit, the method then comprising:

while the mobile communication device is not engaged in a communication activity, continuing charging of the battery using a constant voltage charge regime;

while the mobile communication device is engaged in a communication activity, the method comprising;

ceasing charging until the battery voltage falls to a preselected threshold; and

upon the battery voltage falling to the preselected threshold, charging the battery with a constant current charge regime until the battery voltage reaches the charge voltage limit.

2. A method of charging a battery as defined in claim 1, wherein charging the battery is controlled by a charge controller in the mobile communication device.

3. A method of charging a battery as defined by claim 1, wherein the charge voltage limit is substantially 4.2 volts.

4. A method of charging a battery as defined by claim 1, wherein the mobile communication device is supplied by a current-limited power supply for charging the battery, while the mobile communication device is engaged in the communication activity, charging and ceasing charging is performed by operating a charge control transistor in an on state and an off state, respectively.

5. A method of charging a battery as defined by claim 4, further comprising providing an intermediate voltage regulator between the current-limited power supply and the charge control transistor.

6. A battery charging system for a mobile communication device, the mobile communication device including an attached rechargeable battery and a current-limited power supply coupled to the mobile communication device for supplying a charging current to the mobile communication device, the battery charging system comprising:

a charge control transistor coupled in series between the current-limited power supply and the rechargeable battery; and

a charge controller for monitoring a battery voltage of the rechargeable battery and controlling operation of the charge control transistor;

wherein the charge controller operates the charge control transistor in an on state while the rechargeable battery is first charged to a charge voltage limit, and subsequently;

while the mobile communication device is not engaged in a communication activity, operating the charge control transistor in a linear mode to maintain a substantially constant voltage at the rechargeable battery; and

while the mobile communication device is engaged in a communication activity, operating the charge control transistor in an off state until the battery voltage falls to a preselected threshold, then operating the charge control transistor in an on state until the charge voltage limit is reached.

7. A battery charging system as defined in claim 6, further comprising an intermediate voltage regulator coupled between the current-limited power supply and the charge control transistor.

8. A battery charge system as defined in claim 7, wherein the intermediate voltage regulator is a linear regulator.

9. A battery charge system as defined in claim 7, wherein the charge control transistor comprises at least one MOSFET transistor.

10. A battery charge system as defined in claim 6, wherein the charge voltage limit is substantially 4.2 volts.

11. A method for charging a battery of a device, the device having a heat-generating subsystem, the method comprising:

coupling an external power supply to the device, the external power supply providing a charge current having a maximum current level;

charging the battery at a substantially constant charging current until a battery voltage of the battery reaches a charge limit threshold, the charging current provided by the external power supply;

Subsequent to the battery voltage reaching the charge limit threshold a first time;

while the heat-generating subsystem is not active, charging of the battery using a constant voltage charge regime;

while the heat-generating subsystem is active, the method comprising;

ceasing charging until the battery voltage falls to a preselected threshold; and

upon the battery voltage falling to the preselected threshold, charging the battery with a constant current charge regime until the battery voltage reaches the charge limit threshold.

12. A method for charging a battery of a device as defined in claim 11, wherein ceasing charging and charging the battery with a constant current charge regime until the battery voltage reaches the charge voltage limit are repeated while the heat-generating subsystem is active.

13. A method for charging a battery of a device as defined in claim 11 wherein charging the battery to the charge limit threshold comprises charging the battery until the battery voltage reaches substantially 4.2 volts.

14. A method for charging a battery of a device having a heat-generating subsystem, the battery being disposed in the device, the charging being controlled by a charge controller in the device, the method comprising:

charging the battery with a substantially constant current until a battery voltage of the battery first reaches a charge limit threshold;

activating the heat-generating subsystem of the device; and

while activating the heat-generating subsystem, alternating between;

ceasing charging until the battery voltage falls to a preselected limit; and

charging the battery with a substantially constant current until the battery voltage again reaches the charge limit threshold.

15. A method for charging a battery as defined in claim 14, wherein activating the heat-generating subsystem comprises periodically transmitting using a radio frequency power supply during a communication activity of the device.

16. A method for charging a battery as defined in claim 14, further comprising:

deactivating the heat-generating subsystem;

charging the battery using a substantially constant current until the battery voltage reaches the charge limit threshold; and

charging the battery at a substantially constant voltage.