Method and apparatus for charging a lead acid battery

• US 6,414,465 B1
• Filed: 06/22/2001
• Issued: 07/02/2002
• Est. Priority Date: 06/22/2001
• Status: Expired due to Fees

• Current Assignee: France/Scott Fetzer Company
• Original Assignee: France/Scott Fetzer Company
• Inventors: Banks, Anthony William, Hopkins, William Thomas, Hickerson, Hugh Edward Jr.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/887,309
• Time in Patent Office: 375 Days
• Field of Search: 320/118, 320/119, 320/100, 320/127, 320/129, 320/130, 320/131, 320/137, 320/125, 320/160, 320/139
• US Class Current: 320/118
• CPC Class Codes: H01M 10/342 Gastight lead accumulators H01M10/121 takes precedence
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery charger for a lead acid battery having a power supply with an input connected to an AC signal and an output connected to the battery. The power supply provides a charge current to the battery. A clock connected to the AC signal provides clock pulses having transitions synchronized with zero crossings of the AC signal. A voltage monitor connected to the battery detects a battery voltage substantially simultaneously with a zero value of the charge current. A charge mode control is connected to the clock and the voltage monitor for commanding different battery charge currents. The voltage monitor includes a temperature compensation circuit. The battery charger includes a display module that can be placed at a location remote from the battery charger and convenient to the user. The battery charger executes a battery charge cycle in which absorption and equalization charge times are variable and automatically set as a function of the state of discharge of the battery, that is, as a function of the bulk charge time. During an initial evaluation period, the battery is tested for a deep discharge condition, and if detected, a desulfation charge current is automatically applied for a time period, for example, two hours.

Claims

1. A battery charger for a lead acid battery comprising:

a power supply having an input adapted to be connected to an AC signal and an output adapted to be connected to the battery, the power supply providing a charge current to the battery;

a clock having an input adapted to be connected to the AC signal and providing output clock pulses having transitions synchronized with zero crossings of the AC signal;

a voltage monitor adapted to be connected to the battery for detecting a battery voltage substantially simultaneously with a zero value of the charge current and providing a battery voltage related signal; and

a charge mode control electrically connected to the voltage monitor and responsive to the clock pulses and the battery voltage related signal for commanding different battery charge currents.

2. The battery charger of claim 1 further comprising a switch operatively connected to the power supply for turning the power supply on and off to provide a series of charge current pulses, and the voltage monitor detecting the battery voltage at a time between the charge current pulses.

3. A method of charging a lead acid battery comprising:

applying a charge current intermittently to the battery;

detecting a battery voltage substantially simultaneously with a zero value of the charge current;

providing a battery voltage related signal in response to detecting the battery voltage; and

commanding different charge currents in response to the battery voltage related signal.

4. The method of claim 3 further comprising:

applying a series to current pulses to the battery; and

detecting the battery voltage at a time between two of the current pulses.

5. The method of claim 4 further comprising:

creating the series of pulses applied to the battery in synchronization with zero crossings of an AC signal providing the charge current.

6. A battery charger for a lead acid battery comprising:

a power supply having

an input adapted to be connected to an AC signal,

an output adapted to be connected to the battery, and

a switch operatively connected to the power supply for turning the power supply on and off;

a clock having an input adapted to be connected to the AC signal and providing output clock pulses having transitions synchronized with zero crossings of the AC signal;

a phase angle controller operatively connected to the switch;

a current monitor adapted to be connected to the battery for detecting charge current in the battery, the current monitor providing a charge current related signal;

a current control having an input responsive to the charge current related signal and an output connected to the phase angle controller, the current control causing the phase angle controller to turn the switch on and off in synchronization with the clock pulses;

a voltage monitor adapted to be connected to the battery for detecting a battery voltage substantially simultaneously with a zero value of the charge current and providing a battery voltage related signal; and

a charge mode control having inputs responsive to the clock pulses and the battery voltage related signal and an output connected to the current control, whereby the charge mode control commands different charge currents as a function of the battery voltage and at least one elapsed time period.

7. The battery charger of claim 6 further comprising a temperature compensation circuit connected to a reference input of the voltage monitor, the temperature compensation circuit comprising:

a diode having a forward voltage drop with a temperature coefficient of about −

2 mv/°

C. at a constant current;

a constant current source connected to the diode; and

an amplifier connected to the diode and having a gain of 2 to double an effect of the forward voltage drop of the diode.

8. A battery charger for a lead acid battery comprising:

a power supply having

an input adapted to be connected to an AC signal,

an output adapted to be connected to the battery, and

a switch disposed between the input and the AC signal for turning the power supply on and off;

a clock having an input adapted to be connected to the AC signal and providing output clock pulses having transitions synchronized with zero crossings of the AC signal;

a voltage monitor adapted to be connected to the battery, the voltage monitor detecting a battery voltage and providing a battery voltage related signal; and

a charge mode control responsive to the battery voltage related signal for commanding different battery charge currents.

9. The battery charger of claim 8 wherein the power supply further comprises a transformer having primary and secondary winding and the switch being disposed between the AC signal and the primary winding of the power supply.

10. A battery charger for a lead acid battery comprising:

a power supply having an input adapted to be connected to an AC signal and an output adapted to be connected to the battery, the power supply providing a charge current to the battery;

a voltage monitor having a first input and a second input adapted to be electrically connected to the battery, the voltage monitor providing a battery voltage related signal;

a voltage divider circuit electrically connected between the battery and the second input of the voltage monitor, the voltage divider dividing the battery voltage to provide a voltage on the second input representing the voltage of a battery cell;

a temperature compensation circuit comprising

a diode located proximate the battery and having a forward voltage drop with a temperature coefficient of about −

2 mv/°

C. at a constant current, and

a multiplier connected between the diode and the first input of the voltage monitor and providing a temperature compensated signal with a temperature coefficient of about −

4 mv/°

C.; and

a charge mode control responsive to the battery voltage related signal for commanding different battery charge currents.

11. The battery charger of claim 10 wherein the multiplier further comprises:

a constant current source connected to the diode; and

an amplifier connected to the diode and having a gain of 2 to double an effect of the forward voltage drop of the diode.

12. A method of charging a lead acid battery comprising:

applying a main charge current to the battery for a first time period terminating upon a battery voltage rising to a first magnitude; and

applying, after the first time period, an absorption charge current to the battery for a second time period determined as a function of a time elapsing from an application of the main charge current until the battery voltage rises to the first magnitude.

13. The method of claim 12 further comprising determining the second time period to be equal to about one-half of the first time period.

14. The method of claim 13 further comprising:

applying a first current to the battery for a first, predetermined time period;

applying, after the first time period, a second current to the battery for a second time period terminating upon a battery voltage rising to a first magnitude; and

applying, after the second time period, a third current to the battery for a third time period determined as a function of the first and second time periods.

15. The method of claim 14 further comprising determining the third time period to be equal to about one-half of the sum of the first and the second time periods.

16. The method of claim 13 further comprising:

applying a large current to the battery for a first, predetermined time period;

applying, after the first time period, a lesser current to the battery for a second time period terminating upon a battery voltage rising to a first magnitude; and

applying, after the second time period, a minimum current to the battery for a third time period determined as a function of the first and second time periods.

17. The method of claim 13 further comprising:

applying a large current to the battery for a first, predetermined time period;

applying, after the first time period, the large current to the battery for a second time period terminating upon a battery voltage rising to a first magnitude; and

applying, after the second time period, a minimum current to the battery for a third time period determined as a function of the first and second time periods.

18. A method of charging a lead acid battery comprising:

applying a main charge current to the battery for a first time period terminating upon a battery voltage rising to a first magnitude; and

applying, after the first time period, an absorption charge current to the battery for a second time; and

applying, after the second time period, an equalization charge current to the battery for a third time period determined as a function of a length of the second time period.

19. The method of claim 18 further comprising determining the third period of time to be about one hour in response to the second period of time being less than about two hours.

20. The method of claim 19 further comprising determining the third period of time to be about two hours in response to the second period of time being between about two hours and about 4 hours.

21. The method of claim 19 further comprising determining the third period of time to be about four hours in response to the second period of time being more than about four hours.

22. A method of charging a lead acid battery comprising:

applying a main charge current to the battery for a first time period terminating upon a battery voltage rising to a first magnitude;

applying, after the first time period, an absorption charge current to the battery for a second time period determined as a function of a time elapsing from an application of the main charge current until the battery voltage rises to the first magnitude; and

applying, after the second time period, an equalization charge current to the battery for a third time period determined as a function of a time elapsing from an application of the main charge current until the battery voltage rises to the first magnitude.

23. A method of charging a lead acid battery comprising:

applying a large current to the battery during a bulk charge period terminating upon a battery voltage rising to a first magnitude;

applying a minimum current to the battery during an absorption charge period determined as a function of a time elapsing from an application of the first current until the battery voltage rises to the first magnitude; and

applying the minimum current to the battery during an equalization charge period determined as a function of a length of the absorption charge period.

24. A method of charging a lead acid battery comprising:

detecting a first battery voltage before applying a charge current;

applying an evaluation current to the battery during an evaluation time period;

detecting a second battery voltage during the evaluation time period;

determining a deep discharge condition in response to the first battery voltage being below a first voltage reference and the second battery voltage being above a second voltage reference; and

applying a desulfation charge current for a first time period in response to determining a deep discharge condition.

25. The method of claim 24 further comprising applying the evaluation current to the battery for a predetermined evaluation time period.

26. The method of claim 25 further comprising applying the evaluation current to the battery for an evaluation time period of about one minute.

27. The method of claim 25 further comprising applying the desulfation charge current for a predetermined time period in response to determining a deep discharge condition.

28. The method of claim 25 further comprising applying the desulfation charge current for a time period of about two hours in response to determining a deep discharge condition.

29. A method of charging a lead acid battery comprising:

detecting a first battery voltage before applying a charge current;

applying a larger current to the battery during an evaluation time period;

detecting a second battery voltage during the evaluation time period;

determining a deep discharge condition in response to the first battery voltage being below a first voltage reference and the second battery voltage being above a second voltage reference;

applying a lesser charge current for a desulfation charge time period in response to determining a deep discharge condition;

applying the lesser charge current to the battery for a bulk charge time period terminating upon a battery voltage rising to a first magnitude; and

applying a minimum charge current to the battery for an absorption charge period determined as a function of the bulk charge period; and

applying the minimum charge current to the battery for an equalization charge period determined as a function of the absorption charge period.

30. A method of charging a lead acid battery comprising:

detecting a first battery voltage before applying a charge current;

applying a larger current to the battery during an evaluation time period;

detecting a second battery voltage during the evaluation time period;

determining a normal discharge condition in response to the first battery voltage not being below a first voltage reference;

applying the larger charge current for a fast charge time period in response to the normal discharge condition;

applying the lesser charge current to the battery for a bulk charge time period terminating upon a battery voltage rising to a first magnitude; and

applying a minimum charge current to the battery for an absorption charge period determined as a function of the fast and bulk charge periods; and

applying the minimum charge current to the battery for an equalization charge period determined as a function of the absorption charge period.

31. A battery charger for a lead acid battery comprising:

a power supply having an input adapted to be connected to an AC signal and an output adapted to be connected to the battery, the power supply having an output providing a charge current to the battery;

a switch operatively connected to the power supply for turning the power supply on and off to provide charge current pulses to the battery;

a remote module locatable remote from the battery charger and having a sensory perceptible indicator representing a state of operation of the battery charger;

a charge control electrically connected to the switch for commanding an operation of the switch to cause the power supply to provide a coded series of charge current pulses to the battery representing a desired state of operation of the sensory perceptible indicator; and

the remote module being electrically connected to the output of the power supply and including a control for decoding the coded series of charge current pulses and operating the sensory perceptible indicator in accordance with the desired state of operation.

32. The battery charger of claim 31 wherein the remote module further comprises a plurality of sensory perceptible indicators.

33. The battery charger of claim 31 wherein the remote module further comprises a plurality of visible indicators.

34. The battery charger of claim 31 wherein the remote module further comprises a plurality of LEDs.

35. The battery charger of claim 31 wherein the coded series of charge current pulses further comprises a combination of an absence and presence of charge current pulses.

36. A method of operating sensory perceptible indicators on a battery charger comprising:

producing a series of charge current pulses to the battery from a power supply having an input connected to an AC signal;

encoding the series of charge current pulses by intermittently omitting in accordance with a code at least one of the charge current pulses from the series of charge current pulses to represent a desired state of operation of one of the sensory perceptible indicators;

detecting with a control in a remote module locatable remote from the battery charger and electrically connected to the output of the power supply an omission of the one of the charge current pulses from the series of charge current pulses;

decoding with the control in the remote module the omission of the one of the charge current pulses from the series of charge current pulses; and

operating the one of the sensory perceptible indicators in accordance with the desired state of operation.

37. The method of claim 36 further comprising iterating the steps of encoding, detecting, decoding and operating to operate all of the sensory perceptible indicators in accordance with their desired states of operation.