Process and apparatus for determining the state of charge of a battery
First Claim
1. A process for determining the state of charge of a battery supplying electrical power to an instrument of the type which includes a current consuming component having at least two consumption levels, one of said levels being a minimum current consumption level defined as a minimum load and a second of said levels being a maximum consumption level defined is a maximum load, said process comprising the steps of:
- (a) monitoring the load condition of said current consuming component to determine if it presents said minimum or said maximum load to said battery;
(b) periodically connecting said battery to a reference load but only when said current consuming component presents said minimum load to said battery;
(c) sampling the voltage across said reference load when said battery is connected to said reference load;
(d) comparing the sampled voltage to a number of predetermined voltage levels each which correspond to a different state of charge of the battery so as to determine the state of charge of the battery; and
(e) generating at least one output signal which indicates a state of charge of the battery as determined by said comparing step.
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Abstract
A process and apparatus for determining the state of discharge of an electric battery by measuring the voltage drop associated with changes in its internal resistance. According to the process, the battery is periodically connected to a reference load for a brief interval during which the voltage at the terminals of the load is measured. The measured analog voltage is converted to a digital signal which is compared to a number of pre-programmed digital levels to determine the state of change of the battery. The apparatus comprises a commutation component controlled by a logic signal, a reference load, a sampler-and-hold circuit, an analog-to-digital converter and a comparator which can be programmed at n levels. The apparatus compares digital signals corresponding to the voltage at the terminals of the reference load with the n programmed levels of the decoder and a signal is generated indicating the level of the electric battery with respect to the levels programmed into the comparator.
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Citations
22 Claims
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1. A process for determining the state of charge of a battery supplying electrical power to an instrument of the type which includes a current consuming component having at least two consumption levels, one of said levels being a minimum current consumption level defined as a minimum load and a second of said levels being a maximum consumption level defined is a maximum load, said process comprising the steps of:
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(a) monitoring the load condition of said current consuming component to determine if it presents said minimum or said maximum load to said battery; (b) periodically connecting said battery to a reference load but only when said current consuming component presents said minimum load to said battery; (c) sampling the voltage across said reference load when said battery is connected to said reference load; (d) comparing the sampled voltage to a number of predetermined voltage levels each which correspond to a different state of charge of the battery so as to determine the state of charge of the battery; and (e) generating at least one output signal which indicates a state of charge of the battery as determined by said comparing step. - View Dependent Claims (2, 3, 4)
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5. An apparatus determining the state of charge of a battery supplying electrical power to an instrument of the type which includes a current consuming component having at least two consumption levels, one of said levels being a minimum current consumption level defined as a minimum load and a second of said levels being a maximum consumption level defined as a maximum load, the apparatus comprising:
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(a) means for monitoring the load condition of said current consuming component to determine if it presents said minimum or said maximum load to said battery; (b) means for periodically connecting said battery to a reference load but only when said current consuming component presents said minimum load to said battery; (c) means for sampling the voltage across said reference load when said battery is connected to said reference load; (d) means for comparing said sampled voltage to a number of predetermined voltage levels each of which correspond to a different state of charge of said battery so as to determine the state of charge of said battery; and (e) means for generating at least one output signal which indicates the state of charge of said battery as determined by said comparing step. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus for determining the state of charge of a battery supplying electrical power to an instrument of the type which includes a current consuming component having at least two consumption levels, one of said levels being a minimum current consumption level defined as a minimum load and a second of said levels being a maximum consumption level defined as a maximum load, the apparatus comprising:
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(a) means for periodically connecting said battery to a reference load when said current consuming component presents said minimum load to said battery; (b) means for sampling the voltage across said reference load when said battery is connected to said reference load; (c) means for comparing said sample voltage to a number of predetermined voltage levels each of which correspond to a different state of charge of said battery so as to determine the state of charge of said battery; and (d) means for generating at least one output signal which indicates the state of charge of said battery as determined by said comparing means, said reference load being selected to draw a current such that the current drawn from said battery by said reference load and said minimum load is approximately equal to the current drawn by said maximum load. - View Dependent Claims (21, 22)
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Specification