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

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.