Method and apparatus for predicting battery reserve time to a specified end-voltage
First Claim
1. A method for predicting a battery reserve time to a specified end voltage embedded in a battery monitoring system including a microprocessor and control circuit, interface circuitry interconnecting the microprocessor and control circuit to the batteries being monitored and including means for sensing battery currents and voltages;
- and the batteries being monitored having a discharge curve with a top down convexity;
the method including the steps of;
periodically measuring a voltage, current of a battery at sequential time intervals;
identifying from the plurality of voltage and current measurements if the battery is discharging;
calculating a slope of the battery discharge characteristic, by determining the slope of the curve represented the plurality of voltage and current measurements and time defining a voltage versus ampere-hours removed;
preparing a matrix of correction factors α
based on discharge performance of the battery relating for various combinations of voltage level and discharge current of the battery;
calculating a first remaining reserve time/capacity using the slope, the correction factor for existing voltage and discharge level and a voltage value δ
V representing a difference between present battery voltage and a specified end voltage according to the relation
space="preserve" listing-type="equation">ah=(δ
V/slope)*α
determining if the battery was fully charged at the start of discharge; and
using the first remaining reserve time/capacity as the suitable value of reserve time/capacity if the battery was fully charged at the start of discharge.
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Accused Products
Abstract
A reserve time predictive system for predicting the capacity of a discharging battery monitors the instant voltage of a battery, its discharge rate and a slope of the voltage vs ampere-hours removed from the battery. The discharge profile of battery voltage vs ampere-hours removed, and the difference between the present and end voltage and the slope of voltage vs ampere-hours remaining is utilized to determine a prediction of reserve time remaining until the battery discharges to the specified end voltage. A combination of remaining reserve time and the measurement of capacity removed also determines the available capacity of the battery from a fully charged state. This information is used as historical data for use in subsequent predictions of battery capacity.
52 Citations
6 Claims
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1. A method for predicting a battery reserve time to a specified end voltage embedded in a battery monitoring system including a microprocessor and control circuit, interface circuitry interconnecting the microprocessor and control circuit to the batteries being monitored and including means for sensing battery currents and voltages;
- and the batteries being monitored having a discharge curve with a top down convexity;
the method including the steps of; periodically measuring a voltage, current of a battery at sequential time intervals; identifying from the plurality of voltage and current measurements if the battery is discharging; calculating a slope of the battery discharge characteristic, by determining the slope of the curve represented the plurality of voltage and current measurements and time defining a voltage versus ampere-hours removed; preparing a matrix of correction factors α
based on discharge performance of the battery relating for various combinations of voltage level and discharge current of the battery;calculating a first remaining reserve time/capacity using the slope, the correction factor for existing voltage and discharge level and a voltage value δ
V representing a difference between present battery voltage and a specified end voltage according to the relation
space="preserve" listing-type="equation">ah=(δ
V/slope)*αdetermining if the battery was fully charged at the start of discharge; and using the first remaining reserve time/capacity as the suitable value of reserve time/capacity if the battery was fully charged at the start of discharge. - View Dependent Claims (2, 3, 4, 5)
- and the batteries being monitored having a discharge curve with a top down convexity;
-
6. A method for predicting a battery reserve time to a specified end voltage embedded in a battery monitoring system including a microprocessor and control circuit, interface circuitry interconnecting the microprocessor and control circuit to the batteries being monitored and including means for sensing battery currents and voltages;
- and the batteries being monitored having a discharge curve with a top down convexity;
the method including the steps of; periodically measuring a voltage, current of a battery at sequential time intervals; identifying from the plurality of voltage and current measurements if the battery is discharging; calculating a slope of the battery discharge characteristic, by determining the slope of the curve representing the plurality of voltage and current measurements and time defining a voltage versus ampere-hours removed; preparing a matrix of correction factors α
based on discharge performance of the battery relating for various combinations of voltage level and discharge current of the battery;calculating a first remaining reserve time/capacity using the slope, the correction factor for existing voltage and discharge level and a voltage value δ
V representing a difference between present battery voltage and a specified end voltage according to the relation
space="preserve" listing-type="equation">ah=(δ
V/slope)*αdetermining a time stage early/beyond early at which the battery is discharging; determining if the battery was fully charged at the start of the discharge; and if discharge is at an early stage and if the discharge curve slope is not too steep predicting reserve time remaining by calculating a first value of remaining time based on existing ah data; if discharge is at an early stage and if the discharge curve slope is too steep determining a second value of remaining reserve time/capacity based on a minimum value of the ah slope; if the battery discharge is beyond an early stage of discharge further determining if the discharge is less than a drop of 30% of the capacity removed from the battery and calculating a third remaining reserve time/capacity as a blend of values of the first and second values of reserve time/capacity as the selected reserve time/capacity.
- and the batteries being monitored having a discharge curve with a top down convexity;
Specification