Battery charger

• US 5,304,916 A
• Filed: 04/11/1990
• Issued: 04/19/1994
• Est. Priority Date: 04/11/1990
• Status: Expired due to Term

• Current Assignee: Compaq Computer Corporation (HP Inc.)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Le, Hung Q., Perkins, Dean P.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Dougherty, Thomas M.
• Application Number:
  US07/508,236
• Time in Patent Office: 1,469 Days
• Field of Search: 320/23, 320/39, 320/40, 320/43
• US Class Current: 320/131
• 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
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems
• CPC Class Codes: Y10S 320/13 Fault detection

Abstract

A battery charger is provided for use in electronic devices such as a portable computer. When the electronic device is being powered by an external source of power, such as an AC adapter, the battery charger charges the batteries in the electronic device. First, the battery charger checks the batteries to determine if they are capable of holding a charge. Next, the batteries are fully charged. After the batteries have been fully charged, the battery charger maintains the charge on the batteries by supplying low current to the batteries. Moreover, since batteries that are not allowed to discharge tend to lose charge more quickly than batteries that are discharged and recharged often, the battery charger is capable of discharging and then recharging the batteries while the electronic device is being externally powered.

Claims

1. A battery charger, comprising:

a battery;

means coupled to said battery for monitoring the voltage of said battery, said voltage monitoring means including;

an analog-to-digital converter coupled to said battery to detect analog voltage across said battery and to provide a digital voltage signal correlative to said detected analog voltage; and

a voltage averager coupled to said digital voltage signal for sampling said digital voltage signal a plurality of times providing a plurality of corresponding digital voltage values, said voltage averager storing said plurality of corresponding digital voltage values and providing an averaged digital voltage signal which is the average of said plurality of digital voltage values;

means coupled to said voltage monitoring means for providing a boost charge signal if the voltage of said battery is below a first predetermined voltage level;

means coupled to said boost charge signal for charging said battery at a first preselected rate in response to said boost charge signal;

a timer; and

means coupled to said timer, said charging means and said voltage monitoring means for terminating the charging of said battery at said first preselected rate and for indicating a fault condition if the voltage of said battery is not greater than said first predetermined level after said battery has charged at said first preselected rate for a first predetermined time period.

2. The battery charger of claim 1, wherein said voltage monitoring means further comprises:

a comparator having a first and a second input, said first input coupled to said averaged digital voltage signal and said second input coupled to a digital reference signal, said comparator having an output for providing a signal indicative of said averaged digital voltage signal being greater or less than said digital references voltage.

3. The battery charger of claim 2, further including:

means for receiving an extended charge signal provided externally;

means coupled to said extended charge signal and said voltage monitoring means for partially discharging said battery in response to said extended charge signal if the voltage of said battery is above a second predetermined level, wherein said battery is discharged until the voltage of said battery reaches a third predetermined level, said second predetermined level being greater and said third predetermined level being less than said first predetermined level.

4. The battery charger of claim 3, further comprising:

a voltage reference circuit coupled to said boost signal, said extended charge signal, a mode A signal and a mode B signal, for providing said digital reference signal,

wherein said digital reference signal corresponds to said first predetermined level if said boost signal is being received, said digital reference signal corresponds to said second predetermined level if said extended charge signal and said mode A signal are being received, and said digital reference signal corresponds to said third predetermined level if said extended charge signal and said mode B signal are being received.

5. A battery charger, comprising

a battery;

means coupled to said battery for monitoring the voltage of said battery;

means coupled to said voltage monitoring means for providing a boost charge signal if the voltage of said battery is below a first predetermined voltage level;

means coupled to said voltage monitoring means for providing a fast charge signal if the voltage level of said battery is above said first preselected level;

means coupled to said voltage monitoring means for providing a trickle charge signal if the voltage of said battery is above a second predetermined level, wherein said second predetermined level is greater than said first predetermined level;

means coupled to said boost charge signal, said fast charge signal and said trickle charge signal for charging said battery at a first preselected rate in response to said boost charge signal or said fast charge signal, said charging means further including means for charging said battery at a second preselected rate in response to said charge signal wherein said second preselected rate is lower than said first preselected rate;

a timer;

means coupled to said timer, said charging means, and said voltage monitoring means for terminating the charging of said battery at said first preselected rate and for indicating a fault condition if the voltage of said battery is not greater than said first predetermined level after said battery has charged at said first preselected rate for a first predetermined time period;

means for receiving an extended charge signal provided externally; and

means coupled to said extended charge signal and said voltage monitoring means for partially discharging said battery in response to said extended charge signal if the voltage of said battery is above a third predetermined level, wherein said battery is discharged until the voltage of said battery reaches a fourth predetermined level, said third predetermined level being greater and said fourth predetermined level being less than said first predetermined level.

6. The battery charger of claim 5, wherein said means for partially discharging said battery is coupled to said timer and discontinues discharging said battery and indicates a fault condition if the voltage of said battery does not reach said fourth predetermined level after a third predetermined time period while said battery is being discharged.

7. The battery charger of claim 5, further including means coupled to said fast charge signal for disabling said extended charge signal if said fast charge signal is being provided.

8. A battery charger, comprising:

a battery;

means coupled to said battery for monitoring the voltage of said battery including means for converting the voltage of said battery to a corresponding digital voltage signal;

means coupled to said voltage monitoring means for providing a boost charge signal if the voltage of said battery is below a first predetermined voltage level;

means coupled to said voltage monitoring means for providing a fast charge signal if the voltage level of said battery is above said first preselected level;

means coupled to said boost charge signal and said fast charge signal for charging said battery at a first preselected rate in response to said boost charge signal or said fast charge signal;

a timer;

means coupled to said timer, said charging means and said voltage monitoring means for terminating the charging of said battery at said first preselected rate and for indicating a fault condition if the voltage of said battery is not greater than said first predetermined level after said battery has charged at said first preselected rate for a first predetermined time period;

a register having an input and an output, said input being coupled to said digital voltage signal, said register providing a previous digital voltage signal at its output;

a first comparator having a first and a second input, said first input being coupled to said digital voltage signal and said second input being coupled to said previous digital voltage signal, said first comparator having an output providing a peak charge signal in response to said digital voltage signal being greater than said previous digital signal;

an adder having a first and a second input and an output, said first input being coupled to said digital voltage signal and said second input being coupled to a preselected digital signal, said adder providing a summed signal at said adder output in response to said peak charge signal, wherein said summed signal is the addition of said digital voltage signal and said preselected digital signal;

a second comparator having a first input and a second input, said first input being coupled to said summed signal and said second input being coupled to said previous digital voltage signal, said second comparator having an output providing a fast charge end signal in response to said summed signal being less than said previous digital voltage signal; and

means coupled to said fast charge end signal for providing a trickle charge signal in response to said fast charge end signal being provided, wherein said charging means is coupled to said trickle charge signal and further includes means for charging said battery at a second preselected rate in response to said trickle charge signal wherein said second preselected rate is less than said first preselected rate.

9. A battery charger, comprising:

a battery;

means coupled to said battery for monitoring the voltage of said battery;

means coupled to said voltage monitoring means for providing a boost charge signal if the voltage of said battery is below a first predetermined voltage level;

means coupled to said voltage monitoring means for providing a fast charge signal if the voltage of said battery is above said first preselected level;

means coupled to said boost charge signal and said fast charge signal for charging said battery at a first preselected rate in response to said boost charge signal or said fast charge signal;

a timer; and

means coupled to said timer, said charging means, said fast charge signal and said voltage monitoring means for terminating the charging of said battery at said first preselected rate and for indicating a fault condition if the voltage of said battery is not greater than said first predetermined level after said battery has charged at said first preselected rate for a first predetermined time period, and for terminating the charging of said battery at said first preselected rate if the voltage of said battery is not greater than a second predetermined level after a second predetermined time period initiated by said fast charge signal.

10. The battery charger of claim 9, wherein said second predetermined time period is approximately twelve hours.