Battery pack having a processor controlled battery operating system

• US 5,652,502 A
• Filed: 06/07/1995
• Issued: 07/29/1997
• Est. Priority Date: 11/10/1994
• Status: Expired due to Fees

• Current Assignee: Microchip Technology Incorporated
• Original Assignee: Duracell Incorporated (Berkshire Hathaway Incorporated)
• Inventors: Friel, Daniel D., Hull, Matthew P., Taylor, Alwyn H., Wieczorek, Rudi, van Phuoc, Duong, Zeising, Elmar, Hruska, Louis W.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US08/473,340
• Time in Patent Office: 783 Days
• Field of Search: 320/5, 320/19, 320/20, 320/22, 320/30, 320/35, 320/48, 324/426, 361/96, 361/106, 364/483, 364/350, 364/550
• US Class Current: 702/63
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• 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 6/5011 for several cells simultaneously or successively
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10S 320/13 Fault detection

Abstract

A smart battery device which provides electrical power and which reports predefined battery parameters to an external device having a power management system, includes: at least one rechargeable cell connected to a pair of terminals to provide electrical power to an external device during a discharge mode and to receive electrical power during a charge mode, as provided or determined by the remote device; a data bus for reporting predefined battery identification and charge parameters to the external device; analog devices for generating analog signals representative of battery voltage and current at said terminals, and an analog signal representative of battery temperature at said cell; a hybrid integrated circuit (IC) having a microprocessor for receiving the analog signals and converting them to digital signals representative of battery voltage, current and temperature, and calculating actual charge parameters over time from the digital signals, the calculations including one calculation according to the following algorithm;

CAP.sub.rem =CAP.sub.FC -ΣI.sub.d Δt.sub.d -ΣI.sub.s

Δt+Σε_c I_c Δt_c

wherein ε_c is a function of battery current and temperature; and I_s is a function of battery temperature and CAP_FC. Superimposed on this equation is reset logic, that self corrects the value of CAP_FC with a capacity calculation at each full charge (EOC) and each end of full discharge.

Claims

1. The combination of a portable computer having a power management system, a smart charger, a data bus and a smart battery which provides electrical power to said portable computer and which reports predefined battery parameters to said computer over said data bus, said combination comprising:

(a) a smart battery having

(i) at least one rechargeable cell connected to a pair of terminals to provide electrical power to said portable computer during a discharge mode and to receive electrical power from said smart charger during a charge mode, as determined by said power management system,

(ii) analog means for generating analog signals representative of battery voltage and current at said terminals, and an analog signal representative of battery temperature at said cell,

(iii) a hybrid integrated circuit having a microprocessor for receiving the analog signals and converting the analog signals to digital signals representative of battery voltage, current and temperature, and calculating actual charge parameters over time from said digital signals, said calculations including one calculation according to the following algorithm

space="preserve" listing-type="equation">CAP.sub.rem =CAP.sub.FC -Σ

I.sub.d Δ

t.sub.d -Σ

I.sub.s Δ

t.sub.s +Σ

ε

.sub.c I.sub.c Δ

t.sub.c

wherein CAP_rem is remaining battery capacity, CAP_FC is full charge battery capacity, I_d is battery discharge current, Δ

t_d is a period of time of the discharge current I_d, I_s is battery self discharge current and is a function of battery temperature and CAP_FC, Δ

t_s is a period of time of the self discharge current I_s, ε

is a charging efficiency factor and is a function of battery current and temperature, I_c is battery charging current, and Δ

t_c is a period of time of the charging current I_c, and

(vi) a bus controller having a bus master and a bus slave for sending and receiving battery messages to and from said portable computer over said data bus,

(b) a portable computer having a bus master and a bus slave for sending and receiving battery messages to and from said smart battery over said data bus,

(c) a smart charger responsive to said portable computer and at least one battery message broadcast by said smart battery in a bus master mode to return a requested rate of charge to said smart battery.

2. A combination portable computer-rechargeable battery, comprising:

a portable computer;

a rechargeable battery system including

i) terminal means connected to the portable computer,

ii) a rechargeable battery including at least one rechargeable battery cell connected to the terminal means,

iii) means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current,

iv) a processor for receiving the signals representing battery voltage, battery temperature and battery current, and for performing predefined calculations using said signals to calculate values for defined variables, and

v) a memory area for storing data values including at least values representing battery voltage, battery temperature and battery current;

a data bus connected to the portable computer and the battery system to transmit data between the portable computer and the battery system;

wherein the portable computer includes means for transmitting messages over the data bus to the processor requesting said calculated values;

wherein the processor includes means for receiving the messages from the computer and, in response to receiving said messages, transmitting to the computer the calculated values;

said means for receiving the message having an abled state and a disabled state;

in the abled state, the receiving means is able to receive requests from the computer; and

in the disabled state, the receiving means is disabled from receiving requests from the computer; and

further wherein the processor performs said predefined calculations at regular periods, each of said periods having first and second intervals; and

during the first interval of each of said periods, the processor performs said predefined calculations and places the receiving means in the disabled state.

3. A combination according to claim 2, wherein all of the digital values needed by the processor to perform said predefined calculation are received by the processor from the combination of (i) the memory area and (ii) the means to sense, and to generate signals representing, battery voltage, battery temperature and battery current.

4. A combination according to claim 2, wherein the processor included means for calculating a predicted remaining battery life at a present rate of current discharge by the battery.

5. A combination according to claim 2, further comprising a battery re-charger connected to the terminal means for supplying electrical power to the battery;

and wherein;

the data bus is connected to the portable computer, the battery system and the battery recharger to transmit data between the portable computer, the battery system and the battery recharger;

wherein the battery recharger includes means to transmit messages to the processor requesting identified values; and

the processor further includes means for receiving the messages from the battery recharger and, in response to receiving said messages from the battery recharger, transmitting to the battery recharger the identified values.

6. A combination according to claim 2, wherein:

the battery has charge-discharge cycles, each of said cycles having a charging portion and a discharging portion; and

the processor includes

i) means to detect ends of the discharging portions of the charge-discharge cycles, and

ii) means to calculate an actual full capacity of the battery at the detected ends of the discharging portions of the charge-discharge cycles.

7. A combination portable computer-rechargeable battery according to claim 2, wherein:

the battery has a discharge mode for supplying electrical current to the terminal means and to the portable computer, and a charge mode for receiving electrical current from the terminal means;

the processor performs a given series of calculations at predefined intervals; and

at each of said intervals,

i) if the battery is in the discharge mode, the processor determines the amount of charge supplied by the battery since the most recent previous one of said intervals, and

ii) if the battery is in the charge mode, the processor determines the amount of charge supplied to the battery since the most recent previous one of said intervals.

8. A combination portable computer-rechargeable battery, comprising:

a portable computer;

a rechargeable battery system including

i) terminal means connected to the portable computer,

ii) a rechargeable battery including at least one rechargeable battery cell connected to the terminal means,

iii) means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current,

iv) a processor for receiving the signals representing battery voltage, battery temperature and battery current, and for performing predefined calculations using said signals to calculate values for defined variables, and

v) a memory area for storing data values including at least values representing battery voltage, battery temperature and battery current;

a data bus connected to the portable computer and the battery system to transmit data between the portable computer and the battery system;

wherein the portable computer includes means for transmitting messages over the data bus to the processor requesting said calculated values; and

wherein the processor includes

(i) means for receiving the messages from the computer and, in response to receiving said messages, transmitting to the computer the calculated values,

ii) means for calculating a predicted remaining battery life at a present rate of current discharge by the battery,

iii) means to calculate a remaining capacity of the battery,

iv) means to calculate a full capacity of the battery,

v) means to calculate an adjustment factor,

vi) means to calculate an uncertainty in the remaining capacity of the battery; and

wherein the means for calculating the predicted remaining battery life calculates said remaining battery life according to the equation;

##EQU8## where, T is the predicted remaining battery life, C_r is the calculated remaining capacity of the battery

C_f is the calculated full capacity of the battery,

x is said adjustment factor,

C.sub.ε

is the calculated uncertainty in the remaining capacity of the battery, and

I is the battery discharge current.

9. A combination portable computer-rechargeable battery, comprising:

a portable computer;

a rechargeable battery system including

i) terminal means connected to the portable computer,

ii) a rechargeable battery including at least one rechargeable battery cell connected to the terminal means,

iii) means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current,

iv) a processor for receiving the signals representing battery voltage, battery temperature and battery current, and for performing predefined calculations using said signals to calculate values for defined variables, and

v) a memory area for storing data values including at least values representing battery voltage, battery temperature and battery current, wherein one of the values stored in the memory area is a nominal full capacity of the battery;

a data bus connected to the portable computer and the battery system to transmit data between the portable computer and the battery system;

wherein the portable computer includes means for transmitting messages over the data bus to the processor requesting said calculated values; and

wherein the processor includes means for receiving the messages from the computer and, in response to receiving said messages, transmitting to the computer the calculated values.

10. A combination according to claim 9, wherein the processor further includes means to reset said nominal full capacity value.

11. A method of operating a combination portable computer-rechargeable battery system, the rechargeable battery system including at least one rechargeable battery cell, a processor and a memory area, the method comprising:

connecting the rechargeable battery to the portable computer to supply electrical power thereto;

sensing, and generating analog signals representing, battery voltage, battery temperature and battery current;

storing data values in the memory area, said stored data values including at least values representing battery voltage, battery temperature and battery current;

the processor performing predefined calculations using said signals representing battery voltage, battery temperature and battery current to calculate values for defined variables; and

transmitting data and messages between the portable computer and the battery system, including the steps

i) transmitting messages from the portable computer to a receiving means on the processor requesting said calculated values, and

ii) the processor, in response to receiving said messages, transmitting to the computer the calculated values;

wherein the receiving means has an abled state and a disabled state;

in the abled state, the receiving means is able to receive requests from the computer; and

in the disabled state, the receiving means is disabled from receiving requests from the computer; and

further wherein the step of performing predefined calculations includes the steps of

i) performing the predefined calculations at regular periods, each of said periods having first and second intervals, and

ii) during the first interval of each of said periods, the processor performing said predefined calculations and placing the receiving means in the disabled state.

12. A method according to claim 11, wherein:

the battery has a discharge mode for supplying electrical current to the terminal means and to the portable computer, and a charge mode for receiving electrical current from the terminal means;

the processor performs a given series of calculations at predefined intervals; and

at each of said intervals,

i) if the battery is in the discharge mode, the processor determining the amount of charge supplied by the battery since the most recent previous one of said intervals, and

ii) if the battery is in the charging mode, the processor determining the amount of charge supplied to the battery since the most recent previous one of said intervals.

13. A method according to claim 11, wherein all of the digital values needed by the processor to perform said predefined calculations are received by the processor from the combination of (i) the memory area and (ii) the means to sense, and to generate signals representing, battery voltage, battery temperature and battery current.

14. A method according to claim 11, wherein the step of performing the predefined calculations includes the step of calculating a predicted remaining battery life at a present rate of current discharge by the battery.

15. A method according to claim 11, wherein:

the combination further includes a battery recharger connected to the battery for supplying electrical power to the battery; and

the step of transmitting data and messages includes the steps of

i) the battery recharger transmitting messages to the processor requesting identified values, and

ii) the processor, in response to receiving the messages from the battery recharger, transmitting to the battery recharger the identified values.

16. A method of operating a combination portable computer-rechargeable battery system, the rechargeable battery system including at least one rechargeable battery cell, a processor and a memory area, the method comprising:

connecting the rechargeable battery to the portable computer to supply electrical power thereto;

sensing, and generating analog signals representing, battery voltage, battery temperature and battery current;

storing data values in the memory area, said stored data values including at least values representing battery voltage, battery temperature and battery current, and a value representing nominal full capacity of the battery;

the processor performing predefined calculations using said signals representing battery voltage, battery temperature and battery current to calculate values for defined variables; and

transmitting data and messages between the portable computer and the battery system, including the steps

i) transmitting messages from the portable computer to the processor requesting said calculated values, and

ii) the processor, in response to receiving said messages, transmitting to the computer the calculated values.

17. A method of operating a combination portable computer-rechargeable battery system, the rechargeable battery system including at least one rechargeable battery cell, a processor and a memory area, the method comprising:

connecting the rechargeable battery to the portable computer to supply electrical power thereto;

sensing, and generating analog signals representing, battery voltage, battery temperature and battery current;

storing data values in the memory area, said stored data values including at least values representing battery voltage, battery temperature and battery current;

the processor performing predefined calculations using said signals representing battery voltage, battery temperature and battery current to calculate values for defined variables;

transmitting data and messages between the portable computer and the battery system, including the steps

i) transmitting messages from the portable computer to the processor requesting said calculated values, and

ii) the processor, in response to receiving said messages, transmitting to the computer the calculated values;

discharging the battery during discharging cycles; and

the processor, (i) detecting ends of the discharging cycles, and (ii) calculating an actual full capacity of the battery at the detected ends of the discharging cycles.

18. A method according to claim 17, further including the step of, at each of said intervals, the processor also determining the amount of current internally discharged by the battery since the most recent previous one of said intervals.

19. A method of operating a combination portable computer-rechargeable battery system, the rechargeable battery system including at least one rechargeable battery cell, a processor and a memory area, the method comprising:

connecting the rechargeable battery to the portable computer to supply electrical power thereto;

sensing, and generating analog signals representing, battery voltage, battery temperature and battery current;

storing data values in the memory area, said stored data values including at least values representing battery voltage, battery temperature and battery current;

the processor performing predefined calculations using said signals representing battery voltage, battery temperature and battery current to calculate values for defined variables; and

transmitting data and messages between the portable computer and the battery system, including the steps

i) transmitting messages from the portable computer to the processor requesting said calculated values, and

ii) the processor, in response to receiving said messages, transmitting to the computer the calculated values; and

wherein;

the step of storing data values includes the step of storing a full capacity value representing a full capacity of the battery and a remaining capacity value representing remaining capacity of the battery;

the step of performing predefined calculations includes the steps of periodically resetting the full capacity value, and periodically calculating the remaining capacity of the battery; and

the step of calculating the remaining capacity of the battery includes the step of calculating the remaining capacity of the battery according to the equation

space="preserve" listing-type="equation">CAP.sub.REM ;

=CAP.sub.rem -Σ

.sub.d -Σ

.sub.s +Σ

.sub.c

where

CAP_REM on the left side of the equal sign is the remaining capacity of the battery,

CAP_REM on the right side of the equal sign is the most recent previously calculated value for the remaining capacity of the battery,

Σ

_d is the amount of charge internally discharged in the battery since the remaining capacity of the battery was most recently reset, Σ

_s is the amount of charge discharged by the battery since the remaining capacity of the battery was most recently reset, and

Σ

_c is a percentage of the amount of charge supplied to the battery since the remaining capacity of the battery was most recently reset.

20. A battery pack comprising:

terminal means for connecting the battery pack to a battery powered device and to a battery recharger;

a battery including at least one rechargeable battery cell connected to the terminal means, said battery having

i) a discharge mode for supplying electrical power to the battery powered device, and

ii) a charge mode for receiving electrical power from the terminal means;

means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current;

a memory area for storing data values including values representing battery voltage, battery temperature and battery current, said memory area including a plurality of look-up tables, each of said tables containing a multitude of values;

a processor for receiving the signals representing battery voltage, battery temperature and battery current, connected to the memory area to receive values therefrom, and for performing predefined calculations using said signals and values, wherein said predefined calculations require a plurality of values from look-up tables, and wherein all of said required values are obtained from the look-up tables in the memory area.

21. A battery pack according to claim 20, wherein:

one of the values stored in the memory area is a full capacity of the battery; and

one of said look-up tables contains a multitude of residual capacity correction factors stored as a function of the battery discharging current and battery temperature.

22. A battery pack according to claim 21, wherein:

one of said calculations is a calculation of the residual capacity of the battery; and

the residual capacity of the battery is calculated according to the equation;

space="preserve" listing-type="equation">Residual Capacity=(Full Capacity)(x)

where x is based on a residual capacity correction factor obtained from said one of the look up tables.

23. A battery pack according to claim 20, wherein:

the battery has a relative state of charge;

the battery has a self-discharge current;

one of said look-up tables contains a multitude of self-discharge currents stored as a function of the battery temperature and the relative state of charge of the battery;

one of said calculations is a calculation of the amount of current self-discharged by the battery over a given time period; and

the amount of current self discharged by the battery over a given time period is calculated according to the equation;

space="preserve" listing-type="equation">S=I.sub.s Δ

t.sub.s

where, S is the amount of current self-discharged by the battery over the given time period,

Δ

t_s is the length of the given time period, and

I_s is the self-discharge current obtained from said one of the look-up tables.

24. A battery pack according to claim 20, wherein:

the battery has a relative state of charge and a charging current;

one of said look-up tables contains a multitude of current efficiency factors stored as a function of battery relative state of charge and battery charging current;

one of said calculations is a calculation of an amount of charge added to the battery over a given time period;

the amount of charge added to the battery over a given time period is calculated according to the equation;

space="preserve" listing-type="equation">C=IΔ

tε

where, C is the charge added to the battery,

I is the average current supplied to the battery during the given time period,

Δ

t is the length of the given time period, and

ε

is a current efficiency factor obtained from said one of the look-up tables.

25. A battery pack comprising:

terminal means for connecting the battery pack to a battery powered device and to a battery recharger;

a battery including at least one rechargeable battery cell connected to the terminal means, said battery having

i) a discharge mode for supplying electrical power to the battery powered device, and

ii) a charge mode for receiving electrical power from the terminal means;

means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current;

a memory area for storing data values including values representing battery voltage, battery temperature and battery current, said memory area including a plurality of look-up tables, said plurality of look-up tables including

i) a first look-up table containing a multitude of residual capacity correction factors stored as a function of battery discharging current and battery temperature,

ii) a second look-up table containing a multitude of self-discharge currents stored as a function of battery temperature and the relative state of charge of the battery, and

iii) a third look-up table containing a multitude of current efficiency factors stored as a function of the relative state of charge of the battery and battery charging current; and

a processor for receiving the signals representing battery voltage, battery temperature and battery current, connected to the memory area to receive values therefrom, and for performing predefined calculations using said digital signals and values.

26. A method of operating a battery system having a rechargeable battery, a processor and a memory area, the method comprising:

connecting the rechargeable battery to a battery powered device to supply electrical power thereto;

sensing, and generating signals representing, battery voltage, battery temperature and battery current;

storing data values in the memory area, said stored data values including at least values representing battery voltage, battery temperature and battery current;

storing additional values in a plurality of look-up tables in the memory area; and

the processor performing predefined calculations using values from the memory area and using the signals representing battery voltage, battery temperature and battery current, wherein said predefined calculations require a plurality of values from look-up tables, and all of said required values are obtained from the look-up tables in the memory area.

27. A method according to claim 26, wherein:

one of the values stored in the memory area is a full capacity of the battery; and

one of said look-up tables in the memory area contains a multitude of residual capacity correction factors stored as a function of the battery discharging current and battery temperature.

28. A method according to claim 27, wherein:

the step of the processor performing predefined calculations includes the step of the processor calculating a residual capacity of the battery according to the equation;

space="preserve" listing-type="equation">Residual Capacity=(Full Capacity)(x)

where x is based on a residual capacity correction factor obtained from said one of said look-up tables.

29. A method according to claim 27, wherein:

one of said look-up tables in the memory area contains a multitude of current efficiency factors stored as a function of battery relative state of charge and battery charging current; and

the step of the processor performing predefined calculations includes the step of calculating an amount of charge added to the battery over a given period according to the equation;

space="preserve" listing-type="equation">C=IΔ

tε

where, C is the charge added to the battery,

I is the average current supplied to the battery during the given time period, and

ε

is a current efficiency factor obtained from said one of the look-up tables.

30. A method according to claim 27, wherein:

one of said look-up tables in the memory area contains a multitude of self-discharge current values stored as a function of the battery temperature and the relative state of charge of the battery, and

the step of the processor performing predefined calculations includes the step of the processor calculating an amount of current self-discharged by the battery over a given time period according to the equation;

S=I_s Δ

t_s

where, S is the amount of current self-discharged by the battery over the given time period,

Δ

t_s is the length of the given time period, and

I_s is the self-discharge current obtained from said one of the look-up tables.

31. A combination portable computer-rechargeable battery, comprising:

a portable computer;

a rechargeable battery system including

i) terminal means connected to the portable computer,

ii) a rechargeable battery including at least one rechargeable battery cell connected to the terminal means,

iii) means to sense, and to generate signals representing, battery voltage, battery temperature, and battery current,

iv) a processor for receiving the signals representing battery voltage, battery temperature and battery current, and for performing predefined calculations using said signals to calculate values for defined variables, and

v) a memory area for storing data values including at least values representing battery voltage, battery temperature and battery current;

a data bus connected to the portable computer and the battery system to transmit data between the portable computer and the battery system;

wherein the portable computer includes means for transmitting messages over the data bus to the processor requesting said calculated values;

wherein the processor includes means for receiving the messages from the computer and, in response to receiving said messages, transmitting to the computer the calculated values; and

further wherein the processor performs a given series of calculations at predefined intervals; and

at each of said intervals, the processor determines the amount of current internally discharged by the battery since the most recent previous one of said intervals.

32. A combination portable computer-rechargeable battery according to claim 31, wherein:

said stored values further include a full capacity value representing a full capacity of the battery and a remaining capacity value representing remaining capacity of the battery;

the processor periodically resets said full capacity value; and

the processor calculates the remaining capacity of the battery according to the equation

space="preserve" listing-type="equation">CAP.sub.REM ;

=CAP.sub.rem -Σ

.sub.d -Σ

.sub.s +Σ

.sub.c

where;

CAP_REM on the left side of the equal sign is the remaining capacity of the battery,

CAP_REM on the right side of the equal sign is the most recent previously calculated value for the remaining capacity of the battery,

Σ

_d is the amount of charge internally discharged in the battery since the remaining capacity of the battery was most recently reset,

Σ

_s is the amount of charge discharged by the battery since the remaining capacity of the battery was most recently reset, and

Σ

_C is a percentage of the amount of charge supplied to the battery since the remaining capacity of the battery was most recently reset.