US 5,606,242 AGranted

Smart battery algorithm for reporting battery parameters to an external device

AssigneeDuracell Inc.

InventorsMatthew P. Hull, Alwyn H. Taylor, Louis W. Hruska, Daniel D. Friel

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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 -.SIGMA.I.sub.d .DELTA.t.sub.d -.SIGMA.I.sub.s .DELTA.t+.SIGMA..epsilon..sub.c I.sub.c .DELTA.t.sub.c wherein .epsilon..sub.c is a function of battery current and temperature; and I.sub.s is a function of battery temperature and CAP.sub.FC. Superimposed on this equation is reset logic, that self corrects the value of CAP.sub.FC with a capacity calculation at each full charge (EOC) and each end of full discharge.

Claims31

Dependent claims

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;
CAP.sub.rem =CAP.sub.rem -.SIGMA.I.sub.d .DELTA.t.sub.d -.SIGMA.I.sub.s .DELTA.t.sub.s +.SIGMA..epsilon..sub.c I.sub.c .DELTA.t.sub.c
wherein CAP.sub.rem is remaining battery capacity, CAP.sub.FC is full charge battery capacity, I.sub.d is battery discharge current, .DELTA.t.sub.d is a period of time of the discharge current I.sub.d, I.sub.s is battery self discharge current and is a function of battery temperature and CAP.sub.FC, .DELTA.t.sub.s is a period of time of the self discharge current I.sub.s, .epsilon..sub.c is a charging efficiency factor and is a function of battery current and temperature, I.sub.c is battery charging current, and .DELTA.t.sub.c is a period of time of the charging current I.sub.c,
(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.

5 more elements

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:

(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;
CAP.sub.rem =CAP.sub.rem -.SIGMA.I.sub.d .DELTA.t.sub.d -.SIGMA.I.sub.s .DELTA.t.sub.s +.SIGMA..epsilon..sub.c I.sub.c .DELTA.t.sub.c
wherein CAP.sub.rem is remaining battery capacity, CAP.sub.FC is full charge battery capacity, I.sub.d is battery discharge current, .DELTA.t.sub.d is a period of time of the discharge current I.sub.d, I.sub.s is battery self discharge current and is a function of battery temperature and CAP.sub.FC, .DELTA.t.sub.s is a period of time of the self discharge current I.sub.s, .epsilon..sub.c is a charging efficiency factor and is a function of battery current and temperature, I.sub.c is battery charging current, and .DELTA.t.sub.c is a period of time of the charging current I.sub.c,
(c) storing .epsilon..sub.c as an empirical function of battery current, temperature, and remaining capacity in a look-up table;
storing CAP.sub.FC as a learned value between integrations, and storing I.sub.s as an empirical function of battery temperature and CAP.sub.FC, 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.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/318,004Filed 4 Oct 1994
Granted: 25 Feb 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H02J 7/44
Characterised by the exchange of charge or discharge related data: between battery management systems and power sources
H02J 7/485
Circuit arrangements for charging or discharging batteries or for supplying loads from batteries: with provisions for charging different types of…
H02J 7/94
Regulation of charging or discharging current or voltage: in response to battery current
H02J 7/96
Regulation of charging or discharging current or voltage: in response to battery voltage