Smart battery algorithm for reporting battery parameters to an external device
First Claim
1. A smart battery which provides electrical power and which reports predefined battery parameters to an external device having a power management system, said smart battery comprising:
- (a) 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 said remote device,(b) a data bus for reporting predefined battery identification and charge parameters to the external device,(c) an 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,(d) 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 said digital signals, said calculations including one calculation according to the following algorithm;
space="preserve" listing-type="equation">CAP.sub.rem =CAP.sub.rem -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 CAPrem is remaining battery capacity, CAPFC is full charge battery capacity, Id is battery discharge current, Δ
td is a period of time of the discharge current Id, Is is battery self discharge current and is a function of battery temperature and CAPFC, Δ
ts is a period of time of the self discharge current Is, ε
c is a charging efficiency factor and is a function of battery current and temperature, Ic is battery charging current, and Δ
tc is a period of time of the charging current Ic,(e) a data memory defined within said hybrid IC for storing said predefined battery identification and actual charge parameters, even when nominally fully discharged, said charge parameters including at least full charge capacity and remaining capacity, and(f) a bus controller defined within said hybrid IC for sending battery messages to said remote device over said data bus, said messages including said predefined battery identification and said actual charge parameters.
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Abstract
A smart battery 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+Σεc Ic Δtc
wherein εc is a function of battery current and temperature; and Is is a function of battery temperature and CAPFC. Superimposed on this equation is reset logic, that self corrects the value of CAPFC with a capacity calculation at each full charge (EOC) and each end of full discharge.
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Citations
31 Claims
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1. A smart battery which provides electrical power and which reports predefined battery parameters to an external device having a power management system, said smart battery comprising:
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(a) 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 said remote device, (b) a data bus for reporting predefined battery identification and charge parameters to the external device, (c) an 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, (d) 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 said digital signals, said calculations including one calculation according to the following algorithm;
space="preserve" listing-type="equation">CAP.sub.rem =CAP.sub.rem -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.cwherein CAPrem is remaining battery capacity, CAPFC is full charge battery capacity, Id is battery discharge current, Δ
td is a period of time of the discharge current Id, Is is battery self discharge current and is a function of battery temperature and CAPFC, Δ
ts is a period of time of the self discharge current Is, ε
c is a charging efficiency factor and is a function of battery current and temperature, Ic is battery charging current, and Δ
tc is a period of time of the charging current Ic,(e) a data memory defined within said hybrid IC for storing said predefined battery identification and actual charge parameters, even when nominally fully discharged, said charge parameters including at least full charge capacity and remaining capacity, and (f) a bus controller defined within said hybrid IC for sending battery messages to said remote device over said data bus, said messages including said predefined battery identification and said actual charge parameters. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of charging a rechargeable battery and reporting predefined battery parameters to an external device having a power management system that receives power from, and supplies power to, said rechargeable battery, said method comprising:
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(a) generating analog signals representative of battery voltage and current at a battery input terminal and at a battery output terminal, and generating an analog signal representative of battery temperature at said cell, (b) converting said analog signals to digital signals representative of battery voltage, current and temperature, and integrating actual battery charge parameters over time from said digital signals with a RISC microprocessor associated with said batter according to the following algorithm;
space="preserve" listing-type="equation">CAP.sub.rem =CAP.sub.rem -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.cwherein CAPrem is remaining battery capacity, CAPFC is full charge battery capacity, Id is battery discharge current, Δ
td is a period of time of the discharge current Id, Is is battery self discharge current and is a function of battery temperature and CAPFC, Δ
ts is a period of time of the self discharge current Is, ε
c is a charging efficiency factor and is a function of battery current and temperature, Ic is battery charging current, and Δ
tc is a period of time of the charging current Ic,(c) storing ε
c as an empirical function of battery current, temperature, and remaining capacity in a look-up table;
storing CAPFC as a learned value between integrations, and storing Is as an empirical function of battery temperature and CAPFC, said look-up tables defined by a data memory associated with said battery;(d) storing said predefined battery identification and actual charge parameters in said data memory, said charge parameters including at least full charge capacity and remaining capacity, and (e) sending battery messages to said remote device over a data bus, said messages including said predefined battery identification parameters and said actual charge parameters. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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Specification