Detecting an end of life for a battery using a difference between an unloaded battery voltage and a loaded battery voltage
First Claim
1. A circuit for detecting the end of life of a battery of an electronic device comprising:
- a first node electrically connected to a battery;
a load intermittently electrically connected to the first node, the load configured to be applied and removed from the circuit;
a sample and hold circuit electrically connected to the first node, the sample and hold circuit configured to sample and hold an unloaded battery voltage, the sample and hold circuit comprising;
a capacitor electrically connected between a second node and ground;
a first operational amplifier comprising an inverting input, a non-inverting input and an output, wherein the non-inverting input is electrically connected to the second node and the output is electrically connected to the inverting input; and
a field effect transistor comprising a base terminal, a drain terminal, a gate terminal and a source terminal, wherein the base terminal and the source terminal are electrically connected to the first node and the drain terminal is electrically connected to the second node; and
a differential amplifier electrically connected to the sample and hold circuit, the differential amplifier configured to calculate and amplify a difference between the sampled unloaded battery voltage and a loaded battery voltage.
1 Assignment
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Accused Products
Abstract
One particular implementation conforming to aspects of the present invention takes the form of a method for detecting the end of life of a battery for an electronic device. The method may include calculating the voltage of the battery in an unloaded state, holding the sampled unloaded battery voltage, measuring a loaded battery voltage, calculating the difference between the unloaded and loaded battery voltages and amplifying the calculated difference. Other implementations may take the form of a circuit to perform one or more of the operations of the above method. The circuit may include a sample and hold section and a differential amplifier to provide the amplified difference to a microcontroller for analysis. The microcontroller may also provide a warning or indication to the device or to a user of the device when the battery nears the end of life.
93 Citations
10 Claims
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1. A circuit for detecting the end of life of a battery of an electronic device comprising:
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a first node electrically connected to a battery; a load intermittently electrically connected to the first node, the load configured to be applied and removed from the circuit; a sample and hold circuit electrically connected to the first node, the sample and hold circuit configured to sample and hold an unloaded battery voltage, the sample and hold circuit comprising; a capacitor electrically connected between a second node and ground; a first operational amplifier comprising an inverting input, a non-inverting input and an output, wherein the non-inverting input is electrically connected to the second node and the output is electrically connected to the inverting input; and a field effect transistor comprising a base terminal, a drain terminal, a gate terminal and a source terminal, wherein the base terminal and the source terminal are electrically connected to the first node and the drain terminal is electrically connected to the second node; and a differential amplifier electrically connected to the sample and hold circuit, the differential amplifier configured to calculate and amplify a difference between the sampled unloaded battery voltage and a loaded battery voltage. - View Dependent Claims (2, 3, 4, 5)
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6. A method for detecting the end of the life of a battery of an electronic device comprising:
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sampling a voltage of a battery while the battery is unloaded using a sample and hold circuit that comprises; a capacitor electrically connected between a second node and ground; a first operational amplifier comprising an inverting input, a non-inverting input and an output, wherein the non-inverting input is electrically connected to the second node and the output is electrically connected to the inverting input; and a field effect transistor comprising a base terminal, a drain terminal, and a source terminal, wherein the base terminal and the source terminal are electrically connected to a first node that is electrically connected to a battery and the drain terminal is electrically connected to the second node; storing the sampled unloaded battery voltage using the capacitor in the sample and hold circuit; measuring a voltage of the battery while a load is applied to the battery; calculating a difference between the sampled unloaded battery voltage and the measured loaded battery voltage; amplifying the calculated difference using a differential amplifier circuit; and comparing the amplified difference to a predetermined value to detect the end of the life of the battery. - View Dependent Claims (7)
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8. A system for detecting the end of the life of a battery of an electronic device comprising:
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a sample and hold circuit configured to sample the unloaded voltage of a battery, the sample and hold circuit comprising; a capacitor electrically connected between a second node and ground; a first operational amplifier comprising an inverting input, a non-inverting input and an output, wherein the non-inverting input is electrically connected to the second node and the output is electrically connected to the inverting input; and a field effect transistor comprising a base terminal, a drain terminal, and a source terminal, wherein the base terminal and the source terminal are electrically connected to a first node that is electrically connected to a battery and the drain terminal is electrically connected to the second node; a differential amplifier circuit configured to receive the sampled unloaded battery voltage from the sample and hold circuit and calculate and amplify a difference between the sampled unloaded battery voltage and a loaded battery voltage; and a microcontroller configured to receive the amplified difference from the differential amplifier and compare the amplified difference with a predetermined threshold value. - View Dependent Claims (9, 10)
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Specification