Method of monitoring motor vehicle's electric power by comparing internal resistance of battery with a predeterminated warning resistance thereof and apparatus therefor
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Abstract
The method comprises coupling an external load having a predetermined resistance directly in series with the battery, conducting a power transistor to supply a transient large current to the battery for sampling voltage of the battery in a set very short period of time, and determining the internal resistance of the battery. The internal resistance of the battery can then be compared with a predetermined warning value of internal resistance of the battery so as to determine whether the former is equal to or larger than the warning value, and displaying a warning on a display if the determination is affirmative. The invention enables a driver to correctly know the condition of the battery in substantially real time while consuming a minimum amount of current.
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Citations
54 Claims
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1-27. -27. (canceled)
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28. A method of evaluating the condition of a battery, comprising the steps of:
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(i) selecting an external load the resistance of which is based on the type of the battery, such that when the load is connected across the battery a large current is drawn;
(ii) selecting a value for the internal resistance of the battery based on its type;
(iii) connecting the external load across the terminals of the battery repetitively for short duration intervals, measuring the voltage across the battery while current is conducted through the load, and taking the average of the measured values of the voltage;
(iv) dividing the average of the measured values of the voltage by the resistance of the external load to determine the current drawn from the battery;
(v) calculating the internal resistance of the battery responsive to the determined value of the current;
(vi) comparing the calculated internal resistance of the battery with the selected value of the internal resistance of the battery so as to determine whether the calculated value is equal to or larger than the selected value or not; and
(vii) displaying a warning on a display if the determination in step (vi) is affirmative. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method of evaluating the condition of a battery, comprising the steps of:
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(1) choosing an external load, the resistance R of which is selected in accordance with the type of the battery to be evaluated;
(2) selecting a value for the nominal internal resistance of the battery in accordance with its type;
(3) sampling the no load voltage Vo1 between two terminals of the battery a plurality of times, and sampling the no load voltage Vo2 between two terminals of the external load a plurality of times, and calculating and storing average values of the voltages Vo1 and Vo2;
(4) providing at least one power transistor controlled for connecting the external load across the battery and repetitively controlling the power transistor(s) to conduct so that a large transient current is drawn from the battery by the load for a plurality of short periods;
(5) while said power transistor(s) are conducting, sampling the load voltage Vi1 between two terminals of the battery, and sampling the load voltage Vi2 between two terminals of the external load, and calculating and storing average values of Vo1 and Vi2;
(6) determining the large transient current drawn by the load I by subtracting Vo2 from Vi2 and dividing by R;
(7) calculating the internal resistance r of the battery by subtracting Vo1 from Vi1 and dividing by the transient large current I;
(8) comparing the internal resistance of the battery r to be measured with the selected nominal value thereof to determine the condition of the battery. - View Dependent Claims (39)
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40. An apparatus for monitoring the condition of a battery by determining its internal resistance and comparing the value thereof with a predetermined value therefor selected in accordance with the type of the battery, comprising:
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a controller for controlling the apparatus so as to sample the voltage across the battery responsive to imposition of a known external load chosen responsive to the type of the battery, calculate an internal resistance of the battery to be measured, and compare the internal resistance of the battery to be measured with a predetermined value therefor;
an external load having a predetermined resistance;
a voltage-sampling circuit for sampling voltage across the terminals of the battery;
a transient current control circuit including a power transistor connected across the battery so as to be controlled by the controller to connect the load across the battery so that a large transient current is drawn by the external load from the battery; and
a display responsive to the controller for displaying a warning responsive to comparison of the calculated value of the internal resistance of the battery to the predetermined value thereof. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A method of measuring the internal resistance of a battery, comprising the steps of:
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(1) choosing an external load, the resistance R of which is selected in accordance with the type of the battery to be evaluated;
(2) selecting a value for the nominal internal resistance of the battery in accordance with its type;
(3) sampling the no load voltage Vo1 between two terminals of the battery a plurality of times, and sampling the no load voltage Vo2 between two terminals of the external load a plurality of times, and calculating and storing average values of the voltages Vo1 and Vo2;
(4) providing at least one power transistor controlled for connecting the external load across the battery and repetitively controlling the power transistor(s) to conduct so that a large transient current is drawn from the battery by the load for a plurality of short periods;
(5) while said power transistor(s) are conducting, sampling the load voltage Vi1 between two terminals of the battery, and sampling the load voltage Vi2 between two terminals of the external load, and calculating and storing average values of Vo1 and Vi2;
(6) determining the large transient current drawn by the load I by subtracting Vo2 from Vi2 and dividing by R; and
(7) calculating the internal resistance r of the battery by subtracting Vo1 from Vi1 and dividing by the transient large current I. - View Dependent Claims (54)
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Specification