Method and apparatus for predicting the remaining capacity and reserve time of a battery on discharge

Claim 3

A method of predicting a remaining reserve capacity and a reserve time of a battery in a process of discharge as recited in claim 1, wherein the step of determining the remaining reserve capacity of the battery further includes expressing a ratio of the remaining reserve capacity (Q) to a maximum theoretical capacity (Q max ) as an exponential function.

Claim 4

A method of predicting a remaining reserve capacity and a reserve time of a battery in a process of discharge as recited in claim 2, wherein the exponential function is: ##EQU7## where Q max , a,b,c,d, and e are predetermined parameters determined by a discharge characteristic curve of the battery.

Claim 5

A method of predicting a remaining reserve capacity and a reserve time of a battery in a process of discharge as recited in claim 1 wherein the step of using the remaining reserve capacity to determine the reserve time comprises calculating a ratio of the remaining reserve capacity (Q) to the discharge current (I).

Claim 8

A method of predicting a reserve time of a discharging battery with a known maximum capacity as recited in claim 5, wherein the step of exponentially-relating the temperature-corrected battery overvoltage to a ratio of the remaining reserve capacity (Q) of the discharging battery to its maximum capacity (Q max ) includes evaluation of the equation; ##EQU9## where a,b,c,d and e are predetermined parameters determined by a discharge characteristic curve of the battery.

Claim 13

Apparatus for predicting a remaining reserve capacity (Q) and a reserve time (t) of a battery, comprising: voltage sensing circuitry connected to a terminal voltage of the battery; current sensing circuitry connected for sensing a discharge current (I) of the battery; a temperature sensing device positioned for sensing a temperature (T) of the battery; a battery monitoring circuit connected to receive input from the voltage sensing circuitry, the current sensing circuitry and the temperature sensing device, and including a reserve time prediction sub-unit having: a stored program controller for controlling and receiving input from the voltage sensing circuitry, the current sensing circuitry and the temperature sensing device and determining if the battery is discharging; memory associated with the stored program controller and including data indicative of a battery open circuit voltage (E oc ), a battery internal resistance (R int ), and a maximum theoretical capacity (Q max ); the stored program controller including instructions for determining a value of: ##EQU16## where η is a temperature-corrected battery overvoltage parameter of the battery, and a,b,c,d, and e are curve fitting parameters, and calculating the reserve time using the equation: ##EQU17##

Claim 14

Apparatus for predicting a remaining reserve capacity (Q) and a reserve time (t) of a battery, comprising: voltage sensing circuitry connected to a terminal voltage of the battery; current sensing circuitry connected for sensing a discharge current (I) of the battery; a temperature sensing device positioned for sensing a temperature (T) of the battery; a battery monitoring circuit connected to receive input from the voltage sensing circuitry, the current sensing circuitry and the temperature sensing device, and including a reserve time prediction sub-unit having: a stored program controller for controlling and receiving input from the voltage sensing circuitry, the current sensing circuitry and the temperature sensing device and determining if the battery is discharging; memory associated with the stored program controller and including data indicative of a battery open circuit voltage (E oc ), a battery internal resistance (R int ), and a maximum theoretical capacity (Q max ); the stored program controller including instructions for determining a value of: ##EQU16## where η is a temperature-corrected battery overvoltage parameter of the battery, and a,b,c,d, and e are curve fitting parameters, and calculating the reserve time using the equation: ##EQU17##

Claim 17

A method of predicting a remaining reserve capacity and a reserve time of a battery as recited in claim 10, wherein the step of determining the remaining reserve capacity of the battery includes expressing a ratio of remaining reserve capacity to a maximum theoretical capacity (Q max ) of the battery as a function of the temperature-corrected battery overvoltage (η), the function being: ##EQU18## .

Claim 18

A method of predicting a remaining reserve capacity (Q) and a reserve time of a battery as recited in claim 11 wherein the function is: ##EQU19## where a,b,c,d and e are curve fitting parameters that tailor the function to a characteristic discharge curve of the battery.

Claim 21

A method of predicting a remaining reserve capacity and a reserve time of a battery as recited in claim 13, further comprising the step of: measuring a temperature of the battery.

Claim 22

A method of predicting a remaining reserve capacity and a reserve time of a battery as recited in claim 14, wherein the temperature of the battery is assumed to be an ambient temperature about the battery.