Method for monitoring remaining battery capacity
First Claim
1. The method of producing a predetermined amount of overcharging performed while replenishing a full charge to lead-acid batteries, comprising the steps of:
- a. obtaining a coulometric summation during battery operation, with open circuit voltage measurements taken during the first few minutes of said battery'"'"'s recovery from use, andb. obtaining open circuit voltage measurements during an initial period of recovery of the battery, andc. adaptively learning said battery'"'"'s size and conditions, for tracking by storing historic operational data in computer memory and calculating from stored data, an adaptation factor, thereby rendering said tracking essentially independent of variations in battery treatment during said tracking, including rest period durations and frequency, cycling frequency, discharge patterns, and battery environment including temperature variations and degree of agitation of said battery,d. visually displaying at least one of the state of charge, remaining ampere hours, time remaining to discharge of full useful current at the current discharge rate, miles remaining to discharge of full useful current, based on the discharge rate,e. providing a warning signal which is at least one of visual or audio signal, when the state of charge is less than a predetermined minimum level, as determined by steps (a), (b) and (c), whereby said overcharging is sufficient to produce sufficient gassing to destratify the battery, but below the level which deteriorates the battery beyond a predetermined acceptable limit.
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Accused Products
Abstract
A complete energy management system for lead-acid batteries. The system is designed for deep discharge batteries in traction vehicle type applications such as electric wheelchairs, electric vehicles, golf carts, or industrial equipment, where more efficient use of lead-acid batteries during both the charging and discharging cycle is needed. This system utilizes current measurements, open circuit voltage measurements during the recovery from charging or discharging, and an adaptation calculation to account for variations in physical battery characteristics, battery treatment, battery environment, and battery aging.
120 Citations
23 Claims
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1. The method of producing a predetermined amount of overcharging performed while replenishing a full charge to lead-acid batteries, comprising the steps of:
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a. obtaining a coulometric summation during battery operation, with open circuit voltage measurements taken during the first few minutes of said battery'"'"'s recovery from use, and b. obtaining open circuit voltage measurements during an initial period of recovery of the battery, and c. adaptively learning said battery'"'"'s size and conditions, for tracking by storing historic operational data in computer memory and calculating from stored data, an adaptation factor, thereby rendering said tracking essentially independent of variations in battery treatment during said tracking, including rest period durations and frequency, cycling frequency, discharge patterns, and battery environment including temperature variations and degree of agitation of said battery, d. visually displaying at least one of the state of charge, remaining ampere hours, time remaining to discharge of full useful current at the current discharge rate, miles remaining to discharge of full useful current, based on the discharge rate, e. providing a warning signal which is at least one of visual or audio signal, when the state of charge is less than a predetermined minimum level, as determined by steps (a), (b) and (c), whereby said overcharging is sufficient to produce sufficient gassing to destratify the battery, but below the level which deteriorates the battery beyond a predetermined acceptable limit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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8. The method of claim 7, wherein following a charging cycle, at least about 10% of the capacity must be removed before the open circuit voltage recovery process is monitored and the open circuit voltage recovery determination is not made when the state of charge is less than about 10%.
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9. The method of claim 8, wherein following a charging cycle, at least about 20% of the capacity must be removed before the open circuit voltage recovery process is monitored and the open circuit voltage recovery determination is not made when the state of charge is less than about 20%.
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10. The method of claim 7, wherein 2(x) is about equal to (y).
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11. The method of claim 1, wherein during the recovery process from a discharging cycle, the open circuit voltage is monitored for about the first seven minutes.
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12. The method of claim 9, wherein during the recovery process from a discharging cycle, the open circuit voltage is monitored for about the first seven minutes.
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13. The method of claim 1, wherein the open circuit voltage is monitored during rest periods provided that:
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1) greater than 20% of the capacity has been removed since previous discharging activity, 2) greater than 5% of the capacity has been removed since since the last time the open circuit voltage recovery was monitored, and 3) the state of charge is greater than 20%.
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14. The method of claim 1, wherein when the state of charge, as monitored by coulometric summation, reaches 80%, charging is terminated, and the open current voltage recovery process is monitored at predetermined rest time interval, and a plurality of consecutive open circuit voltage measurements are taken and averaged, the open circuit voltage recovery slope is calculated, and the state of charge is determined based on said averaged measurements.
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15. The method of tracking with high accuracy, a lead-acid battery'"'"'s state of charge during discharging, comprising the steps of:
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a. obtaining a coulometric summation during battery operation, with open circuit voltage measurements taken during the first few minutes of said battery'"'"'s recovery from use, and b. obtaining open circuit voltage measurements during an initial period of recovery of the battery, and c. adaptively learning said battery'"'"'s size and conditions by storing historic operational data in computer memory and calculating from stored data, an adaptation factor, whereby said tracking is essentially independent of variations in battery treatment during said tracking, including rest period durations and frequency, cycling frequency, discharge patterns, and battery environment including temperature variations and degree of agitation of said battery.
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16. A process of battery energy management utilizing a plurality of methods for monitoring the state of charge of a battery, comprising the steps of:
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a. obtaining a coulometric summation during battery operation by continually measuring said battery'"'"'s current flow and the duration of discharge; b. accessing, for a predetermined time period, the open circuit voltage following discharge, c. storing said coulometric summation and said open circuit voltage reading in a data processor, d. calculating the current state of charge of said battery by applying a preprogrammed formula to said accessed data; e. providing compensation for differences which are created by variations due to battery replacement, battery aging, steady state temperature differentials and the decrease in usable capacity at increasing discharge rates; thereby providing an accurate state of charge of said battery. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. The process of monitoring the remaining capacity of a battery, said monitoring incorporating coulometric summation during operation of said battery, said summation requiring the steps of:
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a. continually monitoring the current of the battery; b. detecting a zero current; c. waiting a predetermined time from said zero current; d. taking a first voltage measurement after said predetermined time; e. waiting an additional predetermined time; f. taking a second voltage measurement after said additional predetermined time; g. predicting the final recovered voltage using a predetermined formula h. relating said predicted final recovered voltage to the remaining capacity whereby compensation is provided for differences which are created by variations due to battery replacement, battery aging, steady state temperature differentials, and the decrease in usable capacity at increasing discharge rates.
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Specification