US4191918A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic electric battery charging apparatus
Assignee: Chloride Group Ltd
•
Filing: 1977-10-05
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Granted: 1980-03-04
•
Expires: 1997-10-05
Abstract
Abstract An automatic electric battery charger which detects when the battery is fully charged by monitoring the rate of rise of battery voltage; when the rate of rise falls below a predetermined value, the charge is terminated. The rate of rise of voltage is detected by comparing an unprocessed battery voltage signal with a signal which follows the battery voltage signal with an exponential lag having a time constant of about 45 minutes. With a low rate of rise of voltage, such as occurs when the battery approaches the fully charged state, the lagging signal will tend to catch up with the unprocessed signal, and when the difference falls below 11 mV per cell, the charged is terminated. In the preferred embodiment, the signal processing is digitally implemented, using a microprocessor.
Inventors
- 👤 Anthony T. Nicholls
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:17
CPC Classifications
H; H01; H01M; H01M10/00; H01M10/42; H01M10/44; H02; H02J; H02J7/00; H02J7/90; H02J7/96; H02J7/963; Y; Y02; Y02E; Y02E60/00; Y02E60/10; Y10; Y10S; Y10S320/00; Y10S320/22; Y10S320/24; Y10S320/28
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
73 words
Automatic electric battery charging apparatus, comprising means arranged to provide a control signal which follows variations in battery voltage comparatively rapidly, and a delayed signal which follows variations in battery voltage comparatively slowly, and means arranged to monitor the control and delayed signals and to reduce the average charging current when the difference between the control and delayed signals, or a signal which follows this difference comparatively rapidly, falls below a predetermined value.
Claim 2
Dependent Claim
73 words
Automatic electric battery charging apparatus, comprising means arranged to provide a control signal which follows variations in battery voltage comparatively rapidly, and a delayed signal which follows variations in battery voltage comparatively slowly, and means arranged to monitor the control and delayed signals and to reduce the average charging current when the difference between the control and delayed signals, or a signal which follows this difference comparatively rapidly, falls below a predetermined value.
Claim 3
Dependent Claim
21 words
Apparatus as claimed in claim 1 in which is so arranged that the control signal follows the battery voltage substantially instantaneously.
Claim 4
Dependent Claim
27 words
Apparatus as claimed in claim 1 which is so arranged that the control signal follows the battery voltage with an exponential lag having a short time constant.
Claim 5
Dependent Claim
16 words
Apparatus as claimed in claim 1 in which the short time constant is approximately two minutes.
Claim 6
Dependent Claim
27 words
Apparatus as claimed in claim 1, which is so arranged that the delayed signal follows the battery voltage with an exponential lag having a long time constant.
Claim 7
Dependent Claim
16 words
Apparatus as claimed in claim 5, in which the long time constant is approximately 45 minutes.
Claim 8
Dependent Claim
48 words
Apparatus as claimed in claim 1, in which the monitoring means is arragned to generate a derived signal which follows the said difference with an exponential lag having a short time constant, and to reduce the average charging current when the derived signal falls below a predetermined value.
Claim 9
Dependent Claim
20 words
Apparatus as claimed in claim 7 in which the short time constant, for the derived signal, is approximately two minutes.
Claim 10
Dependent Claim
118 words
Apparatus as claimed in claim 1, including: means which are arranged to derive a direct charging current from an a.c. supply, and which include impedance to give a taper charge characteristic, whereby the charging current falls substantially with rise of battery voltage; means arranged repeatedly to subtract the delayed signal from the control signal to derive an error signal; means arranged repeatedly to adjust the delayed signal by a small amount dependent on the error signal in a direction to bring the delayed signal closer to the control signal; and means arranged to reduce the average charging current when the error signal, or a signal which follows the error signal comparatively rapidly, falls below the said predetermined value.
Claim 11
Dependent Claim
54 words
Apparatus as claimed in claim 1 which is adapted for charging lead-acid batteries, and which is so arranged that the average charging current is reduced when the said difference between the control and delayed signals falls below a value corresponding to a steady rise of voltage of approximately 15 mV per cell per hour.
Claim 12
Dependent Claim
101 words
Automatic electric battery charging apparatus comprising means for monitoring a control signal which follows variations in battery voltage, and for providing a rate of voltage rise signal which is equal to a weighted average of the rate of rise of the control signal during a preceding part of the charge, the weighting factor being greatest for the most recent rise of the control signal and progressively less for earlier rises, and means for reducing the average charging current when the rate of voltage rise signal, or a signal which follows the rate of voltage rise signal, falls below a predetermined value.
Claim 13
Dependent Claim
101 words
Automatic electric battery charging apparatus comprising means for monitoring a control signal which follows variations in battery voltage, and for providing a rate of voltage rise signal which is equal to a weighted average of the rate of rise of the control signal during a preceding part of the charge, the weighting factor being greatest for the most recent rise of the control signal and progressively less for earlier rises, and means for reducing the average charging current when the rate of voltage rise signal, or a signal which follows the rate of voltage rise signal, falls below a predetermined value.
Claim 14
Dependent Claim
56 words
Apparatus as claimed in claim 1 which includes a digital computer, to which a battery voltage signal is supplied through an analogue-to-digital converter, the computer being programmed to calculate the values of the various signals, and to compare the appropriate signal with the said predetermined value, to ascertain whether the average charging current should be reduced.
Claim 15
Dependent Claim
21 words
Apparatus as claimed in claim 12 in which the computer is a microprocessor, having its program stored in a read-only memory.
Claim 16
Dependent Claim
26 words
Apparatus as claimed in claim 1 which is so arranged that the charge will not be terminated within less than a predetermined period from its commencement.
Claim 17
Dependent Claim
31 words
Apparatus as claimed in claim 1 which is so arranged that the charge will not be terminated unless a signal which follows the battery voltage has risen above a predetermined value.
Claim 18
Dependent Claim
48 words
Apparatus as claimed in claim 15 which is adapted for charging lead-acid batteries, and is so arranged that the charge will not be terminated unless a signal which follows the battery voltage has risen above a value corresponding to a battery voltage of approximately 2.36 volts per cell.
Claim 19
Dependent Claim
38 words
Apparatus as claimed in claim 1 which is arranged to provide a freshening charge at intervals if the battery is left connected to the charger for longer than a predetermined period after the main charge has been terminated.
Claim 20
Dependent Claim
35 words
Apparatus as claimed in claim 1 which is arranged to derive the control signal as the difference between signals corresponding, respectively, to battery voltage and to the voltage of the power supply to the charger.
Claim 21
Dependent Claim
34 words
Apparatus as claimed in claim 18 when appendant to claim 12, in which the signals corresponding to battery voltage and to power supply voltage are both supplied to the computer through the analogue-to-digital converter.
References Cited (Backward Citations)
US3794905A
Cited
US3979658A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-03-04 | 1983-09-03 | 1984-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-04 | 1987-09-03 | 1988-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-04 | 1991-09-03 | 1992-03-04 | $7700.00 | Window Closed / Lapsed |