Battery state-of-charge indicator
First Claim
1. A circuit for monitoring the charge state of a battery supplying discharge current to its normal load circuit under actual load operation during which battery discharge current is subject to magnitude variations and interruptions comprising:
- (a) battery terminal voltage sensing means adapted to provide a scaled battery voltage signal representative of actual battery terminal voltage;
(b) storage means for storing a stored signal whose value is indicative of the state-of-charge of said battery, said stored signal having predetermined first and second values representative of battery terminal voltage under no-load conditions, said first and said second values being representative, respectively, of the fully charged and discharged battery;
(c) means for coupling said sensing means and storage means solely to increase the value of said stored signal at a rapid first rate to the scaled value of said battery voltage signal during intervals when the scaled value of said battery voltage signal exceeds the value of said stored signal;
(d) means for continuously decreasing the value of said stored signal at a slow second rate, said second rate being pre-established to provide for variation of said stored signal from said first value to said second value in a time period approximating the average time required for the fully charged battery to become discharged during normal operation of the load circuit; and
(e) means responsive to the value of said stored signal for providing an indication of battery state-of-charge, whereby said circuit is operative under conditions of variable battery discharge current and without sensing the magnitude of battery discharge current.
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Accused Products
Abstract
A circuit for indicating the charge state of a battery supplying discharge current to its load circuit under actual load operation during which battery discharge current is subject to magnitude variations and interruptions, having means for storing a stored signal whose value is representative of battery state-of-charge, means for rapidly increasing the value of the stored signal to the scaled value of the battery terminal voltage when its scaled value is below that of the battery terminal voltage, first means for decreasing the value of the stored signal at a slow rate preestablished such that the stored signal decreases from a first value representative of a fully charged battery to a second value representative of a discharged battery in a time period approximating the average time required during normal operation of the load circuit for the fully charged battery to become discharged, and second means, operative only during intervals when the battery supplies no discharge current to the load, for decreasing the value of the stored signal at a rate intermediate said slow and fast rates and related to the difference between the scaled values of the battery terminal voltage and the stored signal.
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Citations
16 Claims
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1. A circuit for monitoring the charge state of a battery supplying discharge current to its normal load circuit under actual load operation during which battery discharge current is subject to magnitude variations and interruptions comprising:
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(a) battery terminal voltage sensing means adapted to provide a scaled battery voltage signal representative of actual battery terminal voltage; (b) storage means for storing a stored signal whose value is indicative of the state-of-charge of said battery, said stored signal having predetermined first and second values representative of battery terminal voltage under no-load conditions, said first and said second values being representative, respectively, of the fully charged and discharged battery; (c) means for coupling said sensing means and storage means solely to increase the value of said stored signal at a rapid first rate to the scaled value of said battery voltage signal during intervals when the scaled value of said battery voltage signal exceeds the value of said stored signal; (d) means for continuously decreasing the value of said stored signal at a slow second rate, said second rate being pre-established to provide for variation of said stored signal from said first value to said second value in a time period approximating the average time required for the fully charged battery to become discharged during normal operation of the load circuit; and (e) means responsive to the value of said stored signal for providing an indication of battery state-of-charge, whereby said circuit is operative under conditions of variable battery discharge current and without sensing the magnitude of battery discharge current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit adapted for monitoring the charge state of a battery supplying discharge current to its normal load circuit under actual load operation during which the battery discharge current is subject to magnitude variation and interruption, comprising:
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(a) a battery terminal voltage sensing means adapted to provide a scaled battery voltage signal; (b) storage means for storing a stored signal whose value is indicative of the state-of-charge of said battery; (c) first means for increasing the value of said stored signal to the scaled value of said battery voltage signal at a rapid first rate; (d) second means for decreasing the value of said stored signal at a slow second rate during intervals of battery discharge current; (e) third means for decreasing the value of said stored signal at a third rate intermediate said first and second rates during intervals when battery discharge current is interrupted; and (f) means for utilizing said stored signal to provide an indication representative of the charge state of the battery. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A circuit adapted for monitoring the charge state of a battery supplying discharge current to its normal load under actual load operation during which the battery discharge current is subject to magnitude variation and interruption, comprising:
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(a) means for sensing battery terminal voltage to provide a scaled battery voltage signal; (b) capacitance means for storing a stored signal whose value is indicative of the state-of-charge of said battery; (c) comparison means for comparing the scaled values of said battery voltage signal and said stored signal, said comparison means comprising an output coupled via unilaterally conducting means to said capacitance means for increasing the value of said stored signal to the scaled value of said battery voltage during intervals when the scaled value of said battery voltage signal exceeds the value of said stored signal; (d) constant current discharge means coupled in circuit with said capacitance means for continuously decreasing the value of said stored signal at a predetermined slow rate; (e) additional discharge means coupled in circuit with said capacitance means for decreasing the value of said stored signal at a rate faster than said predetermined slow rate; and (f) means for sensing the presence of battery discharge current and responsive thereto inhibiting operation of said additional discharge means.
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Specification