GB2120472A - Charging batteries - Google Patents
Charging batteries Download PDFInfo
- Publication number
- GB2120472A GB2120472A GB08306563A GB8306563A GB2120472A GB 2120472 A GB2120472 A GB 2120472A GB 08306563 A GB08306563 A GB 08306563A GB 8306563 A GB8306563 A GB 8306563A GB 2120472 A GB2120472 A GB 2120472A
- Authority
- GB
- United Kingdom
- Prior art keywords
- charging
- voltage
- battery
- time
- rate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/00714—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery charging or discharging current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/007—Regulation of charging or discharging current or voltage
- H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
- H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
- H02J7/007184—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage in response to battery voltage gradient
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Secondary Cells (AREA)
Abstract
In a method and an apparatus for charging batteries using a source 3,4 which delivers a charging current which decreases with an increasing battery voltage, the charging current is continuously integrated 14, to determine the total number of ampere hours supplied, the rate of change of the charging voltage is determined 15 and the maximum value of the rate of change established the time (T2, Fig. 1) at which the rate of change of the charging voltage again falls to a predetermined percentage, for example about 40-50%, of its previously established maximum value is then established and charging of the battery is continued from this time (T2) until the battery has been supplied with a further number of ampere hours constituting a predetermined percentage, for example about 10- 15%, of the total number of ampere hours supplied to the battery up to the aforesaid time (T2). Charging of the battery is then discontinued. The battery may subsequently be trickle charged, e.g. by connecting it to the charging current source for a predetermined short period as soon as the battery voltage has fallen to a predetermined level. Calculation of the rate of change of charging voltage may commence only when the charging or battery voltage has reached a predetermined value; the battery may be charged-with a higher current until that time. Means 6,9 may be provided to compensate for mains voltage variations when determining the rate of change of charging voltage. Calculations and control may be effected by a microprocessor 12, and a display 20 may indicate main charging time, additional charging time, total charging time, ampere hour, charging voltage, and charging current. <IMAGE>
Description
SPECIFICATION
Method and apparatus for charging storage batteries
The present invention relates to a method for charging storage batteries using a charging current source which delivers a charging current which falls with increasing charging or battery voltage, and to apparatus by means of which the method for charging storage batteries can be put into effect.
When charging storage batteries, it is of utmost importance that charging is interrupted at the right time, when the battery is fully charged, so that the battery is neither overcharged nor undercharged. Undercharging must be avoided, since this results in sulphating of the battery. It is also necessary to avoid excessive or prolonged overcharging, since this results in heavy gassing of the battery, which is liable to cause damage to the battery in the long run.
Storage batteries are, to a large extent, charged from charging current sources having a so-called W-characteristic, i.e. a falling currentvoltage-characteristic, which provides a charging current which falls with increasing battery voltage. Such a charging source is simple and inexpensive and, for example, may comprise an a.c. mains-connected leakage flux transformer with a following rectifier. One serious disadvantage with such a source, however, is that the charging current and the charging voltage are greatly affected by variations in the mains voltage supplied.
The simplest method of charging a storage battery is to permit charging to continue for a given length of time. As will be understood, this gives no guarantee whatsoever that the battery will not be undercharged or overcharged, since the charging time selected is only based on an assumption of the original state of charge of the battery.
Consequently, when charging large storage batteries, for example batteries for powering electrically driven vehicles, it is normal to use a charging method with a so-called WA-characteristic. In this battery charging method, the charging voltage, i.e. the voltage across the battery, is measured and charging is permitted to continue as a so-called main charge, until the battery voltage has reached a given, predetermined value, normally about 2.4V per cell, which is considered to be the voltage level at which the battery begins to gas. Charging is then continued as so-called additional charging, for a predetermined length of time.It will be apparent, however, that this method is also unable to afford any satisfactory assurance that the battery will have been fully charged, or that the battery will not have been subjected to harmful overcharging when charging is discontinued when said predetermined length of time has lapsed.
Consequently, in order to obtain further improvement in this respect, there has been developed a charging equipment in which the aforementioned additional charging of the battery is not interrupted until it has been established that the charging voltage or charging current has assumed a substantially constant value, at which the battery is considered to be fully charged. The result obtained with this method, however, is also unsatisfactory in practice, since both the charging voltage and the charging current vary very slowly during the final part of the battery-charging operation, and hence it is difficult to establish with satisfactory accuracy, whether the charging voltage or the charging current has reached a constant value or not.This is particularly true when using a charging current source of the aforementioned kind, since with such a source the charging current and charging voltage are greatly affected by any variations which may occur in the mains voltage supply. In an attempt to overcome this disadvantage, certain known charging units have been provided with means for automatically compensating for variations in the mains voltage, so that the charging voltage and the charging current become less sensitive to such variations.
This is expensive, however, and difficult to achieve in practice with sufficient accuracy.
In both of the aforementioned battery-charging
methods with WA-characteristic, a further step
may be applied, in which the charging-current source is switched to a lower current level after the so-called main charging period and prior to the so-called additional charging period, so-called
WOWA-characteristic. In this way, during the
latter part of the charging operation there is obtained a lower charging current than would otherwise be the case. In principle, however, this does not provide any additional possibility of being able to interrupt the charging operation at the correct time with satisfactory precision, i.e.
when the battery has been fully charged and has
not been subjected to overcharging.
Consequently, the object of the present
invention is to provide an improved method for charging storage batteries, which enables the battery to be fully charged with a higher degree of
reliability and accuracy, without undercharging or overcharging the battery. The invention also relates to an apparatus for charging storage
batteries in accordance with the method.
According to the present invention there is provided a method for charging a storage battery when using a charging current source which delivers a charging current which decreases with increasing battery voltage, comprising the steps of continuously measuring the charging current from the time at which charging is commenced, and integrating the current value obtained so that the total number of ampere-hours supplied during that part of the charging period which has passed is continually known; measuring the charging voltage and determining its rate of change; establishing the maximum value of the rate of change of the charging voltage; establishing at which point in time the rate of change of the charging voltage falls to a predetermined percentage of said maximum value; and continuing charging from said point in time until the battery has been supplied with a further number of ampere hours which constitute a predetermined percentage of the total number of ampere hours supplied to the battery before said point in time was reached, and then interrupting the charging of the battery.
According to a further feature of the present invention there is provided an apparatus for charging storage batteries, comprising a charging current source which delivers a charging current which decreases with an increasing battery voltage, in which said apparatus includes means for measuring the charging current and the charging voltage; and a control and calculator unit arranged to receive from said measuring means measuring values corresponding to the charging current and the charging voltage; and in that the control and calculator unit includes a time measuring circuit for measuring the time which has lapsed from the commencement of the charging operation; a current calculating circuit which is supplied with the value of the measured current and which is controlled from said time measuring circuit, said circuit being arranged to calculate the total number of ampere hours supplied to the battery from the commencement of the charging operation; a voltage calculating circuit which is arranged to receive the value of the measured voltage and which is controlled from said time measuring circuit, said circuit being arranged to calculate the rate of change of the charging voltage and to establish its maximum value and the point in time at which the rate of change of the charging voltage has again fallen to a pre-determined percentage of its established maximum value; and a control circuit which is controlled from said current and voltage calculating circuits and which is arranged to interrupt the charging operation when the total number of ampere hours supplied to the battery after the aforementioned point in time established by the voltage calculating circuit exceeds the number of ampere hours supplied up to said point in time by a pre-determined percentage.
The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a graph which illustrates the typical course taken by the charging current and the charging voltage when charging a storage battery while using a charging-current source having a falling current-voltage characteristic; and
Figure 2 is a simplified block-diagram of an exemplary embodiment of battery-charging apparatus according to the invention.
The diagram in Figure 1 shows a typical example of the variation of the charging voltage V and the charging current I as a function of time t while charging a storage battery. The voltage V is given in volts per cell, while the current I is given in amperes. As will be seen, both the charging voltage V and the charging current I change very slowly during the latter part of the charging operation, when the battery is fully charged.
Consequently, it is extremely difficult to decide when to interrupt charging, so that the battery is neither undercharged nor overcharged, by attempting to determine when the charging voltage or the charging current adopts a practically constant value. This is particularly the case in practice, since the values of both the charging current and the charging voltage can vary considerably in response to variations in the mains voltage supplied to the charging-current source, particularly when said source comprises, for example, a simple leakage flux transformer with a following rectifier with no special means provided for compensating for variations in the mains voltage.Consequently, if an approximately constant charging voltage or charging current is used as a criterion in deciding whether or not charging is completed there still remains a great deal of uncertainty, which may result in the battery being under-charged or overcharged.
It is believed that the upper "knee" in the charging voltage curve corresponds substantially to the point in time at which the amount of current supplied to the battery, the number of ampere hours, is equal to the amount of current previously removed from the battery. It is desired, however, to continue charging the battery beyond this point, so as to equalize the charge in the various battery cells.
In order to vaoid the previously discussed disadvantages encountered with previously used methods for charging storage batteries, when practicing the method according to the invention the charging current I is continuously measured and the current value obtained is integrated from the commencement of the charging operation so that the total number of ampere hours applied to the battery from the time when charging was commenced is known at any moment of the charging operation. The charging voltage V is also measured, and its rate of change is determined on the basis of this measurement. This can be effected, for example, by comparing the values of the charging voltage at mutually sequential, regularly spaced points of time, for example at time intervals of 10 to 20 minutes. In this way, the maximum value of the rate of change of the charging voltage V is established, this maximum value thus occurring at the steepest part of the voltage curve V, approximately at time T1 in
Figure 1.
When this maximum value for the rate of change of charging voltage V has been reached, the measuring of the charging voltage is continued and its rate of change determined until there is reached during the charging operation that time at which the rate of change of said charging voltage has fallen to a pre-determined percentage of its previously established maximum value. This percentage can lie within the range of about 2560% and preferably of about 4050%, and is so selected, on the basis of previous experience, that it corresponds to the upper "knee" on the charging voltage curve V. This time point is referenced T2 in Figure 1.It will be under stood that these determinations of the maximum change in rate of the charging voltage V and the point in time at which the change in rate of said charging voltage has fallen to a percentage corresponding, for example, to 4050% of the maximum value, can be carried out relatively accurately, since the rate of change of the charging voltage is still relatively high during this part of the charging operation. By determining the time T2 in this way, one has also determined the time during the charging operation at which the battery can be considered to have been supplied with substantially the same amount of current, i.e.
the same number of ampere hours, as that previously drawn from the battery.
Hereinafter, in accordance with the invention, charging of the battery is continued until an additional number of ampere hours, corresponding to a predetermined percentage of the number of ampere hours supplied to the battery from the time charging commenced up to the time point T2, are supplied to the battery subsequent to the time T2 having been reached.
This percentage of the ampere hours additionally supplied may lie within the range of 520%, and preferably lies within the range of about 1 0- 15%, and is so selected as to equalize the charge between the various cells of the battery, in the manner desired. The point in time at which the battery has been supplied with said additional number of ampere hours is referenced T3 in
Figure 1, by way of example, the charging operation being interrupted at this point in time.
By means of the invention it is ensured, with
much greater certainty than when practicing
previously known charging methods, that the
battery will be fully charged without risk of being
undercharged or overcharged.
Advantageously, the rate of change of the charging voltage V is not determined until the
charging voltage has reached a value of about 2.3-2.4 volts per cell, since prior to this the variations in the charging voltage may be extremely irregular.
If, when carrying out a charging operation
according to the invention, it is desired to lower
the level of the charging current, in a manner
known per se, to a lower value after the initial part
of the charging operation, said lowering of the
charging current is suitably effected at the same time as determination of the change in rate of the
charging voltage commences, for example at a
charging voltage of 2.3 volts per cell.
When the battery has been charged in the
aforedescribed manner, the battery can be held
on a compensating or trickle charge in
accordance with a suitable known method, for
example, by re-connecting the charging-current
source for a short period of time, for example for a
period of two minutes, as soon as the battery
voltage has fallen to a value of, for example, about 2.17-2.20 volts per cell.
Figure 2 is a simplified block diagram of a
battery charging apparatus according to the
invention, for charging storage batteries in accordance with the aforedescribed method.
The charging apparatus comprises connecting terminals 1 ,for connection to an a.c. mains, and connecting terminals 2 for connection to the battery to be charged. The charging current source comprises a power transformer 3, for example of the leakage flux type, with a following rectifier 4, and may be connected to or disconnected from the a.c. mains respectively by means of an automatic switch means 5. The charging apparatus also comprises means 6 for measuring the mains voltage supplied, means 7 for measuring the charging current, and means 8 for measuring the charging voltage or the battery voltage. The measuring means 6, 7 and 8 are connected to respective A/D-converters 9, 10 and 11, arranged to send digital signals corresponding to the measurement values to a digital control and calculator unit 12, which may comprise, for example, a micro processor.
The control and calculator unit 12 includes a clock 13, which controls a current calculating circuit 1 4 and a voltage calculating circuit 1 5. The value of the charging current from the current measuring means 7 and the AlD-converter 10 is supplied to the current calculating circuit 14, which is constructed to integrate this value, so that information concerning the total number of ampere hours supplied to the battery from the time at which the charging operation commenced is constantly available during said charging operation.The value of the charging voltage from the voltage measuring means 8 and the A/Dconverter 11 is supplied to the voltage calculating circuit 15, which is constructed so as to determine the change in rate of the charging voltage when the said charging voltage has reached a predetermined value, for example 2.3 volts per cell, for example by comparing the values of the charging voltage with each other at regularly occurring intervals. In this way, the voltage calculating circuit 1 5 establishes the maximum value of the rate of change of the charging voltage, and also establishes the time at which the rate of change of the charging voltage has again fallen to a predetermined percentage, for example 4050%, of the maximum value.At this point of time, which is referenced T2 in the diagram of Figure 1 , the voltage calculating circuit 1 5 sends a signal to a control circuit 16, to which information concerning the total number of ampere hours supplied to the battery since the commencement of the charging operation is also sent from the current calculating circuit 14. The
control circuit 1 6 is constructed to ensure that the battery is supplied with a further number of ampere hours subsequent to receiving the signal from the voltage calculating circuit 1 5 at time T2,
said further number of ampere hours constituting
a predetermined percentage, for example about 10-1 5%, of the total number of ampere hours
supplied to the battery up to time T2. When this
has taken place, the control circuit 16 auto
matically operates the automatic switch means 5,
so as to interrupt the supply of voltage to the power transformer 3 and therewith terminate charging of the battery.
The voltage measuring means 6 and the A/Dconverter 9 also supply the voltage calculating circuit 1 5 with information concerning the mains voltage, so that when calculating the rate of change of the charging voltage, the voltage calculating circuit 1 5 is able to compensate for variations in the mains voltage. This enables the rate of change of the charging voltage to be calculate with a high degree of accuracy.
The control and calculator unit 12 also includes counters 17, 18 and 19, which are controlled by the clock 1 3 and which are arranged to calculate the total charging time, the main charging time and the additional charging time respectively. In this respect, the counters 18 and 19 are also activated from the voltage calculating circuit 16, in a manner such that the counter 18 calculates the so-called main charging time up to the point in time when the charging voltage reaches a value of, for example, 2.3 volts per cell, while the counter 1 9 calculates the subsequent so-called additional charging time.
The charging apparatus also includes a display unit 20, to which information is supplied from the circuits 14, 15, 18 and 19 in the control and calculator unit 12, said display unit thus being able to present the number of ampere hours supplied, the value of the charging voltage, the total charging time, the main charging time, and the additional charging time. Naturally, other values can also be presented in a similar manner, such as the magnitude of the charging current for example.
As will readily be understood, the charging apparatus according to the invention may also comprise other, conventional components and functions known per se, for example safety circuits arranged to discontinue the charging process should, for example, the battery cells short circuit and in other abnormal circumstances.
Claims (12)
1. A method for charging a storage battery when using a charging current source which delivers a charging current which decreases with increasing battery voltage, comprising the steps of continuously measuring the charging current from the time at which charging is commenced, and integrating the current value obtained so that the total number of ampere hours supplied during that part of the charging period which has passed is continually known; measuring the charging voltage and determining its rate of change; establishing the maximum value of the rate of change of the charging voltage; establishing at which point in time the rate of change of the charging voltage fails to a pre-determined percentage of said maximum value; and continuing charging from said point in time until the battery has been supplied with a further number of ampere hours which constitute a predetermined percentage of the total number of ampere hours supplied to the battery before said point in time was reached, and then interrupting the charging of the battery.
2. A method as claimed in claim 1, in which said predetermined percentage of the maximum value of the rate of change of the charging voltage lies within the range of 2560%, preferably 4050%.
3. A method as claimed in claim 1 or claim 2, in which said predetermined percentage of the total number of ampere hours supplied to the battery prior to said point in time lies within the range 520%, preferably 10-1 5%.
4. A method as claimed in any one of claims 1 to 3, in which determination of the change of rate of the charging voltage is not commenced until the charging voltage has reached a level of about 2.3-2.4 volts per cell.
5. A method as claimed in claim 4, in which the charging current is lowered to a lower level before commencing to determine the change of rate of the charging voltage.
6. A method as claimed in any one of claims 1 to 5, in which the mains voltage supplying the charging current source is measured and, when determining the change of rate of the charging voltage, compensation is made for any effect which variations in the mains voltage may have had.
7. An apparatus for charging storage batteries, comprising a charging current source which delivers a charging current which decreases with an increasing battery voltage, in which said apparatus includes means for measuring the charging current and the charging voltage; and a control and calculator unit arranged to receive from said measuring means measuring values corresponding to the charging current and the charging voltage; and in that the control and calculator unit includes a time measuring circuit for measuring the time which has lapsed from the commencement of the charging operation; a current calculating circuit which is supplied with the value of the measured current and which is controlled from said time measuring circuit, said circuit being arranged to calculate the total number of ampere hours supplied to the battery from the commencement of the charging operation; a voltage calculating circuit which is arranged to receive the value of the measured voltage and which is controlled from said time measuring circuit, said circuit being arranged to calculate the rate of change of the charging voltage and to establish its maximum value and the point in time at which the rate of change of the charging voltage has again fallen to a predetermined percentage of its established maximum value; and a control circuit which is controlled from said current and voltage calculating circuits and which is arranged to interrupt the charging operation when the total number of ampere hours supplied to the battery after the aforementioned point in time established by the voltage calculating circuit exceeds the number of ampere hours supplied to said point in time by a predetermined percentage.
8. An apparatus as claimed in claim 7, in which the voltage calculating circuit is arranged to commence calculating the change of rate of the charging voltage only when the charging voltage has reached a predetermined value.
9. An apparatus as claimed in claim 7 or claim 8, in which the voltage calculating circuit is arranged to calculate the change of rate of the charging voltage by comparison between the values of the charging voltage at mutually sequential regular intervals.
10. An apparatus as claimed in any one of claims 7 to 9, in which said apparatus comprises means for measuring the supply mains voltage of the charging current source, said measuring value being supplied to the voltage calculating circuit, which is arranged to compensate for variations in the supply mains voltage when calculating the change of rate of the charging voltage.
11. An apparatus for charging storage batteries, constructed and arranged substantially as hereinbefore described with referenced to and as illustrated in the accompanying drawings.
12. A method for charging a storage battery when using a charging current source which delivers a charging current which decreases with increasing battery voltage, substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8201536A SE430192B (en) | 1982-03-11 | 1982-03-11 | PROCEDURE AND DEVICE FOR CHARGING A BATTERY BATTERY |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8306563D0 GB8306563D0 (en) | 1983-04-13 |
| GB2120472A true GB2120472A (en) | 1983-11-30 |
Family
ID=20346232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08306563A Withdrawn GB2120472A (en) | 1982-03-11 | 1983-03-10 | Charging batteries |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3308515A1 (en) |
| GB (1) | GB2120472A (en) |
| SE (1) | SE430192B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2183944A (en) * | 1985-12-09 | 1987-06-10 | Levitt Safety Ltd | Battery charger |
| US4692682A (en) * | 1985-12-23 | 1987-09-08 | Levitt Safety Limited | Nicad battery charger |
| GB2246916A (en) * | 1990-08-10 | 1992-02-12 | Hi Watt Battery Industry Compa | Battery charger |
| US5449996A (en) * | 1992-08-20 | 1995-09-12 | Makita Corporation | Battery charger with improved change stopping capability |
| US5467005A (en) * | 1992-08-11 | 1995-11-14 | Makita Corporation | Battery charger which accounts for initial surge in battery voltage and which is immune to noise during completion of charging |
| EP0803958A2 (en) * | 1996-04-24 | 1997-10-29 | Space Systems / Loral, Inc. | Recharge profile for spacecraft Ni/H2 Batteries |
| EP1451915A1 (en) * | 2001-10-03 | 2004-09-01 | Trojan Battery Company | System and method for battery charging |
| US7589491B2 (en) | 2006-03-10 | 2009-09-15 | Trojan Battery Company | Temperature compensation in recharging of batteries |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3839810A1 (en) * | 1988-11-25 | 1990-05-31 | Bayerische Motoren Werke Ag | Method for controlling the gearshift sequences of an automatic transmission of a motor vehicle |
| US5686815A (en) * | 1991-02-14 | 1997-11-11 | Chartec Laboratories A/S | Method and apparatus for controlling the charging of a rechargeable battery to ensure that full charge is achieved without damaging the battery |
| DK25391D0 (en) * | 1991-02-14 | 1991-02-14 | Pan Europ Holding S A | PROCEDURE AND APPARATUS FOR CHARGING A RECHARGEABLE BATTERY |
| DE4125825A1 (en) * | 1991-08-05 | 1993-02-11 | Rawe Electronik Gmbh | METHOD AND DEVICE FOR RECHARGING CHARGABLE BATTERIES WITH A CHARGER |
| US11186198B2 (en) * | 2019-05-31 | 2021-11-30 | Ford Global Technologies, Llc | Methods and systems for vehicle battery cell failure detection and overcharge protection |
-
1982
- 1982-03-11 SE SE8201536A patent/SE430192B/en not_active IP Right Cessation
-
1983
- 1983-03-10 GB GB08306563A patent/GB2120472A/en not_active Withdrawn
- 1983-03-10 DE DE19833308515 patent/DE3308515A1/en not_active Withdrawn
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2183944A (en) * | 1985-12-09 | 1987-06-10 | Levitt Safety Ltd | Battery charger |
| US4692682A (en) * | 1985-12-23 | 1987-09-08 | Levitt Safety Limited | Nicad battery charger |
| GB2246916A (en) * | 1990-08-10 | 1992-02-12 | Hi Watt Battery Industry Compa | Battery charger |
| US5467005A (en) * | 1992-08-11 | 1995-11-14 | Makita Corporation | Battery charger which accounts for initial surge in battery voltage and which is immune to noise during completion of charging |
| US5449996A (en) * | 1992-08-20 | 1995-09-12 | Makita Corporation | Battery charger with improved change stopping capability |
| EP0803958A2 (en) * | 1996-04-24 | 1997-10-29 | Space Systems / Loral, Inc. | Recharge profile for spacecraft Ni/H2 Batteries |
| EP0803958A3 (en) * | 1996-04-24 | 1998-10-14 | Space Systems / Loral, Inc. | Recharge profile for spacecraft Ni/H2 Batteries |
| EP1451915A1 (en) * | 2001-10-03 | 2004-09-01 | Trojan Battery Company | System and method for battery charging |
| EP1451915A4 (en) * | 2001-10-03 | 2004-12-22 | Trojan Battery Co | System and method for battery charging |
| AU2002211434B2 (en) * | 2001-10-03 | 2006-01-05 | Trojan Battery Company | System and method for battery charging |
| US7129675B2 (en) | 2001-10-03 | 2006-10-31 | Trojan Battery Company | System and method for battery charging |
| US7589491B2 (en) | 2006-03-10 | 2009-09-15 | Trojan Battery Company | Temperature compensation in recharging of batteries |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8306563D0 (en) | 1983-04-13 |
| SE430192B (en) | 1983-10-24 |
| SE8201536L (en) | 1983-09-12 |
| DE3308515A1 (en) | 1983-09-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |