Apparatus and method for testing battery condition
First Claim
1. In a system in which a load is connected across first and second power terminals of a battery, a circuit for sensing the condition of the battery comprising:
- a current source generating a first current;
a resistor;
a selectively enabled current switch, means connecting the current source in series with the resistor, the selectively enabled current switch, and the battery for selectively passing the first current through the resistor and the battery;
means for sensing the voltage across the resistor; and
means for sensing the voltage across the battery for the condition when the selectively enabled switch is open and for the condition when the selectively enabled switch is closed.
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Abstract
In circuits and systems embodying the invention the condition of a battery may be tested and monitored while the battery is supplying a load current to a load and without interrupting that operation. A selectively enabled switch causes a test current to selectively flow through the battery and a test resistor of known value. The voltage across the test resistor is sensed to determine the value of the test current. The voltage across the battery is measured under two conditions, with the test current and without the test current flowing through it. These measurements and knowing the value of the test current enable the internal resistance of the battery under test to be calculated and monitored.
66 Citations
22 Claims
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1. In a system in which a load is connected across first and second power terminals of a battery, a circuit for sensing the condition of the battery comprising:
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a current source generating a first current;
a resistor;
a selectively enabled current switch, means connecting the current source in series with the resistor, the selectively enabled current switch, and the battery for selectively passing the first current through the resistor and the battery;
means for sensing the voltage across the resistor; and
means for sensing the voltage across the battery for the condition when the selectively enabled switch is open and for the condition when the selectively enabled switch is closed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 16, 17, 19, 20, 21, 22)
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12. A system comprising:
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a battery with first and second power terminals;
a load connected across said first and second power terminals with the battery supplying the power to the load, a circuit for sensing the internal resistance of the battery comprising;
a current source for producing a first current;
a resistor;
a selectively enabled current switch, means connecting the current source in series with the resistor, the selectively enabled current switch, and the battery for selectively passing the first current source current through the resistor and the battery;
means for sensing the voltage across the resistor; and
means for sensing the voltage across the battery for the condition when the selectively enabled current switch is open and for the condition when the selectively enabled current switch is closed.
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14. In a system in which a load is connected across first and second power terminals of a battery whereby the battery supplies the load current to the load, a circuit for sensing the condition of the battery comprising:
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a resistor of known value;
a selectively enabled switch for selectively causing a test current to flow through the resistor and the battery, means for sensing the voltage across the resistor; and
means for sensing the voltage across the battery for the condition when the selectively enabled switch is open and for the condition when the selectively enabled switch is closed.
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18. A method for monitoring the condition of a battery, having first and second power terminals across which a load is connected and to which the battery supplies a load current, comprising the steps of:
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selectively causing a resistor of known value to be coupled to the battery for selectively causing a test current to flow through the resistor and the battery, in addition to the load current;
sensing the voltage across the resistor;
sensing the voltage across the battery for the condition when the load current and test current flow through the battery and for the condition when only the load current flows through the battery; and
calculating the value of the battery resistance.
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Specification