US20010011882A1 - Lithium ion battery unit adapted to be charged by an alkaline charger - Google Patents

Lithium ion battery unit adapted to be charged by an alkaline charger Download PDF

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Publication number
US20010011882A1
US20010011882A1 US09/769,357 US76935701A US2001011882A1 US 20010011882 A1 US20010011882 A1 US 20010011882A1 US 76935701 A US76935701 A US 76935701A US 2001011882 A1 US2001011882 A1 US 2001011882A1
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Prior art keywords
battery unit
voltage
safety
connecting terminals
external connecting
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Application number
US09/769,357
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US6304063B2 (en
Inventor
Serge Maloizel
Stephane Jaud
Philippe Boisumault
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Saft Finance SARL
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Alcatel SA
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Assigned to ALCATEL reassignment ALCATEL ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BOISUMAULT, PHILIPPE, JAUD, STEPHANE, MALOIZEL, SERGE
Publication of US20010011882A1 publication Critical patent/US20010011882A1/en
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Assigned to SAFT FINANCE S.AR.L. reassignment SAFT FINANCE S.AR.L. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ALCATEL (FORMERLY KNOWN AS ALCATEL ALSTHOM COMPAGNIE GENERALE D'ELECTRICITE)
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    • 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
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
    • 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
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00308—Overvoltage protection

Definitions

  • the invention relates to a battery unit including at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prevent entry of charging current into the cell as soon as a voltage applied between said external terminals is greater than a particular maximum safety voltage.
  • This kind of battery unit is more particularly intended for powering portable devices such as mobile telephones, camcorders and other devices.
  • Its safety circuit is designed to protect each cell against failure of the charger leading to an overvoltage between the external connecting terminals of the battery unit, for example.
  • a safety circuit of the above kind is described in U.S. Pat. No. 5,547,775. Its role is therefore to prevent deep discharging and overcharging of each cell of the battery unit, for example to prevent a short circuit across the external connecting terminals destroying the cell. It primarily consists of a plurality of excessive overcharging and excessive discharging detector circuits, a plurality of discharge circuits and a plurality of switching circuits associated with the respective cells of the battery unit.
  • Each cell of the battery unit is therefore connected to an overcharging and deep discharging detector circuit, a discharge circuit and a switching circuit.
  • the safety circuit described in the aforementioned document is capable of bringing about discharging of each cell of a battery unit if it detects that the cell has an excessive voltage at its terminals or preventing current being drawn from a cell if it has detected that the cell concerned is deeply discharged.
  • Battery units which include lithium ion cells have a significant advantage in terms of stored energy density and weight saving but lithium ion cells cannot withstand overvoltages at their terminals.
  • the addition of a safety circuit as indicated above to a lithium ion cell battery unit improves the performance and reliability of the battery unit.
  • a charger for an alkaline battery unit modulates its output voltage to generate a constant charging current in the battery unit that it is charging, whereas a lithium ion battery unit charger maintains a constant voltage at the external connecting terminals of the battery unit it is charging.
  • the safety circuit is activated during each charging cycle, although it is intended to operate only as a final resort. This mode of use compromises the reliability of the battery unit: the fact that the safety circuit is regularly activated reduces its reliability and consequently the reliability and safety of the battery unit are themselves reduced.
  • the object of the invention is to remedy these drawbacks.
  • the invention provides a battery unit including at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prohibit entry of charging current into the cell as soon as a voltage applied between the external connecting terminals is greater than a particular maximum safety voltage, in which battery unit an additional protection circuit is connected between the external terminals and the safety circuit to prohibit the entry of charging current into the safety circuit as soon as the voltage applied between the external connecting terminals is greater than a particular maximum charging voltage which is less than the maximum safety voltage.
  • the safety circuit of a lithium ion battery unit is no longer activated each time that the battery unit is charged by an alkaline charger, which helps to maintain the reliability of the battery unit at a satisfactory level, whether it is used with an alkaline charger or with a lithium ion charger.
  • the additional protection circuit includes a MOSFET switch which is controlled to prohibit or authorize the entry of a charging current into the safety circuit.
  • the protection circuit is referred to as closed or open according to whether this MOSFET is turned on or off.
  • a problem that is frequently encountered in controlled switching is oscillation: because of slight disturbances to the voltage caused by opening the circuit, the protection circuit finds itself in a configuration in which it should close again. If precautions against this are not taken, the circuit begins to oscillate indefinitely at the time it should merely open.
  • the MOSFET switch is controlled by a comparator having a first input which receives the maximum charging voltage and a second input which receives the voltage applied to the external connecting terminals, the second input being connected to the external connecting terminals via a divider bridge having a division ratio that varies to introduce hysteresis into the control of the switch.
  • the resulting hysteresis between opening and closing of the switch helps to eliminate the oscillation problem.
  • the circuit closing voltage is made less than the maximum charging voltage (above which the circuit is opened). In this way, when the circuit is opened, the input voltage can fall to some degree (whilst remaining greater than the closing voltage) without closing the circuit.
  • the circuit obtained in this way is stable and is not disturbed by voltage variations caused by its operation.
  • the battery unit according to the invention shown in the FIGURE includes a protection circuit 1 connected between positive and negative external connecting terminals 2 , 3 of the battery unit and a safety circuit 4 .
  • the safety circuit 4 is connected to at least one lithium ion storage cell, in this example to four cells 5 connected in series. As can be seen in the FIGURE, each cell is connected by its two terminals to the safety circuit 4 and the safety circuit 4 also has two terminals 6 and 7 connected to the external connecting terminals 2 and 3 via the protection circuit 1 .
  • the protection circuit 1 includes a voltage divider bridge D connected to the

Abstract

A battery unit includes at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prohibit entry of charging current into the cell as soon as a voltage applied between the external connecting terminals is greater than a particular maximum safety voltage. An additional protection circuit is connected between the external terminals and the safety circuit to prohibit the entry of charging current into the safety circuit as soon as the voltage applied between the external connecting terminals is greater than a particular maximum charging voltage which is less than the maximum safety voltage. This prevents the safety circuit operating unnecessarily.

Description

    BACKGROUND OF THE INVENTION
  • 1. Field of the Invention [0001]
  • The invention relates to a battery unit including at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prevent entry of charging current into the cell as soon as a voltage applied between said external terminals is greater than a particular maximum safety voltage. [0002]
  • 2. Description of the Prior Art [0003]
  • This kind of battery unit is more particularly intended for powering portable devices such as mobile telephones, camcorders and other devices. Its safety circuit is designed to protect each cell against failure of the charger leading to an overvoltage between the external connecting terminals of the battery unit, for example. A safety circuit of the above kind is described in U.S. Pat. No. 5,547,775. Its role is therefore to prevent deep discharging and overcharging of each cell of the battery unit, for example to prevent a short circuit across the external connecting terminals destroying the cell. It primarily consists of a plurality of excessive overcharging and excessive discharging detector circuits, a plurality of discharge circuits and a plurality of switching circuits associated with the respective cells of the battery unit. Each cell of the battery unit is therefore connected to an overcharging and deep discharging detector circuit, a discharge circuit and a switching circuit. In this way the safety circuit described in the aforementioned document is capable of bringing about discharging of each cell of a battery unit if it detects that the cell has an excessive voltage at its terminals or preventing current being drawn from a cell if it has detected that the cell concerned is deeply discharged. [0004]
  • Battery units which include lithium ion cells have a significant advantage in terms of stored energy density and weight saving but lithium ion cells cannot withstand overvoltages at their terminals. The addition of a safety circuit as indicated above to a lithium ion cell battery unit improves the performance and reliability of the battery unit. [0005]
  • From the charging point of view, the various types of cell have different requirements, and at present the chargers employed must be matched to the type of cell that they are intended for charging. A charger for an alkaline battery unit, for example, modulates its output voltage to generate a constant charging current in the battery unit that it is charging, whereas a lithium ion battery unit charger maintains a constant voltage at the external connecting terminals of the battery unit it is charging. [0006]
  • If a lithium ion battery unit is charged with an alkaline charger, on approaching the end of charging the resistance of the lithium ion cells increases and the charger therefore increases the applied voltage to maintain a constant current, until the point is reached where the voltage applied is greater than the maximum safety voltage of the lithium ion battery unit. The safety circuit of the lithium ion battery unit will then open to isolate the cells from the charger, which represents the end of charging. [0007]
  • If a user who has an alkaline charger regularly uses it to charge a lithium ion battery unit, the safety circuit is activated during each charging cycle, although it is intended to operate only as a final resort. This mode of use compromises the reliability of the battery unit: the fact that the safety circuit is regularly activated reduces its reliability and consequently the reliability and safety of the battery unit are themselves reduced. [0008]
  • This kind of situation occurs frequently: in professional video batteries, for example, the interfaces between the battery unit and the camera are fixed and a lithium ion battery unit therefore has the same interface as an alkaline battery unit. A user can therefore always connect a lithium ion battery unit to an alkaline charger, which has the drawback of causing the battery unit to operate regularly in a safety mode. [0009]
  • The object of the invention is to remedy these drawbacks. [0010]
    • SUMMARY OF THE INVENTION
  • To this end, the invention provides a battery unit including at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prohibit entry of charging current into the cell as soon as a voltage applied between the external connecting terminals is greater than a particular maximum safety voltage, in which battery unit an additional protection circuit is connected between the external terminals and the safety circuit to prohibit the entry of charging current into the safety circuit as soon as the voltage applied between the external connecting terminals is greater than a particular maximum charging voltage which is less than the maximum safety voltage. [0011]
  • With the above arrangement, the safety circuit of a lithium ion battery unit is no longer activated each time that the battery unit is charged by an alkaline charger, which helps to maintain the reliability of the battery unit at a satisfactory level, whether it is used with an alkaline charger or with a lithium ion charger. [0012]
  • In one particular embodiment of a battery unit according to the invention, the additional protection circuit includes a MOSFET switch which is controlled to prohibit or authorize the entry of a charging current into the safety circuit. Hereinafter the protection circuit is referred to as closed or open according to whether this MOSFET is turned on or off. A problem that is frequently encountered in controlled switching is oscillation: because of slight disturbances to the voltage caused by opening the circuit, the protection circuit finds itself in a configuration in which it should close again. If precautions against this are not taken, the circuit begins to oscillate indefinitely at the time it should merely open. In one particular embodiment of the protection circuit according to the invention, the MOSFET switch is controlled by a comparator having a first input which receives the maximum charging voltage and a second input which receives the voltage applied to the external connecting terminals, the second input being connected to the external connecting terminals via a divider bridge having a division ratio that varies to introduce hysteresis into the control of the switch. The resulting hysteresis between opening and closing of the switch helps to eliminate the oscillation problem. The circuit closing voltage is made less than the maximum charging voltage (above which the circuit is opened). In this way, when the circuit is opened, the input voltage can fall to some degree (whilst remaining greater than the closing voltage) without closing the circuit. The circuit obtained in this way is stable and is not disturbed by voltage variations caused by its operation. [0013]
    • BRIEF DESCRIPTION OF THE DRAWING
  • One embodiment of a battery unit according to the invention is described in more detail hereinafter and shown in the single FIGURE of the accompanying drawings. [0014]
    • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • The battery unit according to the invention shown in the FIGURE includes a protection circuit [0015] 1 connected between positive and negative external connecting terminals 2, 3 of the battery unit and a safety circuit 4. The safety circuit 4 is connected to at least one lithium ion storage cell, in this example to four cells 5 connected in series. As can be seen in the FIGURE, each cell is connected by its two terminals to the safety circuit 4 and the safety circuit 4 also has two terminals 6 and 7 connected to the external connecting terminals 2 and 3 via the protection circuit 1. The protection circuit 1 includes a voltage divider bridge D connected to the

Claims (3)

There is claimed:
1. A battery unit including at least one storage cell, two external connecting terminals, one of which is positive and the other of which is negative, and a safety circuit connected to prohibit entry of charging current into said cell as soon as a voltage applied between said external connecting terminals is greater than a particular maximum safety voltage, in which battery unit an additional protection circuit is connected between said external terminals and said safety circuit to prohibit the entry of charging current into said safety circuit as soon as said voltage applied between said external connecting terminals is greater than a particular maximum charging voltage which is less than said maximum safety voltage.
2. The battery unit claimed in
claim 1
 wherein said additional protection circuit includes a MOSFET switch which is controlled to prohibit or authorize entry of a charging current into said safety circuit.
3. The battery unit claimed in
claim 2
 wherein said switch is controlled by a comparator having a first input which receives said maximum charging voltage and a second input which receives said voltage applied to said external connecting terminals and said second input is connected to said external connecting terminals by a divider bridge having a division ratio which varies to introduce hysteresis into the control of said switch.
US09/769,357 2000-02-03 2001-01-26 Lithium ion battery unit adapted to be charged by an alkaline charger Expired - Fee Related US6304063B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0001349 2000-02-03
FR0001349A FR2804800B1 (en) 2000-02-03 2000-02-03 LI-ION BATTERY PACK THAT CAN BE CHARGED BY AN ALKALINE CHARGER

Publications (2)

Publication Number Publication Date
US20010011882A1 true US20010011882A1 (en) 2001-08-09
US6304063B2 US6304063B2 (en) 2001-10-16

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US (1) US6304063B2 (en)
EP (1) EP1122855A1 (en)
FR (1) FR2804800B1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070075682A1 (en) * 2005-09-30 2007-04-05 Guang Huang T Rapid charge lithium ion battery charger
US20090313048A1 (en) * 2000-05-31 2009-12-17 Medidata Ft, Inc. Clinical trials management system and method
US9425644B1 (en) 2015-06-03 2016-08-23 Thor Charger Company Method and apparatus for charging an electrically chargeable device utilizing resonating magnetic oscillations in the apparatus

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6969974B1 (en) * 2004-11-03 2005-11-29 Motorola, Inc. Battery fuel gauge using safety circuit
US7633261B2 (en) * 2007-03-27 2009-12-15 Honeywell International Inc. Primary battery with internal voltage regulator
JP5829966B2 (en) * 2012-03-30 2015-12-09 ルネサスエレクトロニクス株式会社 Battery control semiconductor device and battery pack

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392101A (en) * 1978-05-31 1983-07-05 Black & Decker Inc. Method of charging batteries and apparatus therefor
JP3136677B2 (en) * 1991-07-31 2001-02-19 ソニー株式会社 Overcharge and overdischarge prevention circuit for secondary battery
US5296797A (en) * 1992-06-02 1994-03-22 Byrd Electronics Corp. Pulse modulated battery charging system
US5637413A (en) * 1995-10-16 1997-06-10 Motorola, Inc. Overvoltage disconnect circuit for lithium ion batteries

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090313048A1 (en) * 2000-05-31 2009-12-17 Medidata Ft, Inc. Clinical trials management system and method
US20070075682A1 (en) * 2005-09-30 2007-04-05 Guang Huang T Rapid charge lithium ion battery charger
US20080012533A1 (en) * 2005-09-30 2008-01-17 Guang Huang T Rapid charge lithium ion battery charger
US20080024090A1 (en) * 2005-09-30 2008-01-31 Guang Huang T Rapid charge lithium ion battery charger
US7598709B2 (en) 2005-09-30 2009-10-06 International Components Corporation Rapid charge lithium ion battery charger
US7626362B2 (en) 2005-09-30 2009-12-01 International Components Corporation Rapid charge lithium ion battery charger
US20100033137A1 (en) * 2005-09-30 2010-02-11 Huang Tai Guang Rapid charge lithium ion battery charger
US7683574B2 (en) 2005-09-30 2010-03-23 International Components Corporation Rapid charge lithium ion battery charger
US7898220B2 (en) 2005-09-30 2011-03-01 Icc-Nexergy, Inc. Rapid charge lithium ion battery charger
US9425644B1 (en) 2015-06-03 2016-08-23 Thor Charger Company Method and apparatus for charging an electrically chargeable device utilizing resonating magnetic oscillations in the apparatus

Also Published As

Publication number Publication date
FR2804800B1 (en) 2002-04-26
US6304063B2 (en) 2001-10-16
EP1122855A1 (en) 2001-08-08
FR2804800A1 (en) 2001-08-10

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