EP4710401A1 - Distress beacon comprising a protected electric cell assembly - Google Patents

Distress beacon comprising a protected electric cell assembly

Info

Publication number
EP4710401A1
EP4710401A1 EP24721956.1A EP24721956A EP4710401A1 EP 4710401 A1 EP4710401 A1 EP 4710401A1 EP 24721956 A EP24721956 A EP 24721956A EP 4710401 A1 EP4710401 A1 EP 4710401A1
Authority
EP
European Patent Office
Prior art keywords
electric
protected
electric cell
cells
cell
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.)
Pending
Application number
EP24721956.1A
Other languages
German (de)
French (fr)
Inventor
Sébastien DUSSAUD
Alain Cauhepe
Yannick Toussaint
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Exail Aerospace
Original Assignee
Exail Aerospace
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Exail Aerospace filed Critical Exail Aerospace
Publication of EP4710401A1 publication Critical patent/EP4710401A1/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/574—Devices or arrangements for the interruption of current
    • H01M50/583—Devices or arrangements for the interruption of current in response to current, e.g. fuses
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/50—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries acting upon multiple batteries simultaneously or sequentially
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • H02J7/62—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements against overcurrent
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
    • H02J7/60—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements
    • H02J7/68—Circuit arrangements for charging or discharging batteries or for supplying loads from batteries including safety or protection arrangements using circuits for correcting or protecting against reverse-polarity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/425—Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing
    • H01M2010/4271—Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2200/00—Safety devices for primary or secondary batteries
    • H01M2200/10—Temperature sensitive devices
    • H01M2200/103—Fuse
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2105/00—Networks for supplying or distributing electric power characterised by their spatial reach or by the load
    • H02J2105/30—Networks for supplying or distributing electric power characterised by their spatial reach or by the load the load networks being external to vehicles, i.e. exchanging power with vehicles
    • H02J2105/32—Networks for supplying or distributing electric power characterised by their spatial reach or by the load the load networks being external to vehicles, i.e. exchanging power with vehicles for aircrafts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Materials Engineering (AREA)
  • Connection Of Batteries Or Terminals (AREA)

Abstract

The invention relates to a distress beacon (2) comprising an electric cell assembly (10) comprising two protected electric cells (100) connected in series, each comprising an electric cell (110) having two terminals, a positive and negative electric line (111, 112) respectively connected to the terminals of the electric cell (110), a diode (120) arranged in parallel to the electric cell (110) with its anode connected to the negative electric line (112) and its cathode connected to the positive electric line (111), and an electric fuse (130) arranged in series to the electric cell (110), the electric cells (110) being configured to deliver a nominal current when discharging, the electric fuse (130) having a breaking capacity corresponding substantially to the nominal current, so that, when discharged, the electric cells (110) are each protected from a polarity reversal caused by a forced current driven through it by the other protected electric cell.

Description

TITLE: Distress beacon comprising a protected electric cell assembly
Technical Field
The present disclosure relates to a distress beacon comprising a protected electric cell assembly, and to an aircraft comprising such distress beacon.
Background art
Aircrafts, such as airplanes, are often equipped with distress devices or beacons, known as “Emergency Locator Transmitters” or ELTs, which are powered by an internal battery on which they rely entirely, and are completely separate from the aircraft’s electrical system.
When activated under distress, the beacon’s signal is sent out to pinpoint the aircraft's location. This signal then may be captured by satellites within the international Cospas- Sarsat program.
The internal battery of the beacon allows it to function independently of the rest of the aircraft, allowing to maintain the distress signal for several days during an emergency situation.
Such beacon devices typically incorporate a series of electric cells, in particular lithium- based energy storage cells, which collectively form an electric cell assembly called a battery or battery pack of the beacon.
Electric cells, hereafter also called cells, are electrochemical devices that produce electricity by converting chemical energy into electrical energy through an oxidationreduction reaction. It is to be noted that the electric cells referred to are primary-energy cells, that is, non-rechargeable cells.
In such an electric cell assembly, electric cells may be connected in series, i.e. forming a branch of cells, and/or in parallel.
Electric cells, or electric batteries, are often protected against a reverse voltage applied on their terminals when charging. For example, a well-known technique for avoiding damage due to reverse voltage is the use of a diode connected in series to a cell or to a branch of cells.
Another well-known technique is the use of a mechanical keying, i.e. a mechanical errorproofing, avoiding improper installation and use of a cell or electric battery.
These known solutions allow avoiding damage due to reverse voltage applied at electric cell’s terminals. However, they are limited to applications where the reverse voltage is due to an error of handling or use.
Thus, in a case of proper use of the electric cell or electric battery, these arrangements are not meant to intervene in the electric cell’s or electric battery’s operation, and play no further role.
However, reverse voltage operation of an electric cell, leading to a polarity reversal of an electric cell, may occur when the electric cell is totally or partially discharged, which may lead to a thermal runaway. This event may occur even in case of correct handling or use of the electric cell assembly. This critical failure of an electric cell assembly can instigate various alarming incidents, among others ignition or even explosion of the batteries, which may cause tremendous damage when occurring within an aircraft.
Consequently, in the context of distress beacons, ensuring the integrity and safety of batteries within these beacons is a crucial issue, due to the risks associated with their operational failure.
Summary of the disclosure
It is an aim of the present disclosure to provide a distress beacon comprising a battery with electric cells which are protected against damage due to thermal runaway caused by polarity reversal in one or more of the electric cells.
According to a first aspect of the present disclosure, there is provided a distress beacon comprising an electric cell assembly itself comprising at least two protected electric cells connected in series, wherein the protected electric cells each comprise an electric cell having two terminals, a positive electric line and a negative electric line respectively connected to the terminals of the electric cell, a diode arranged in parallel to the electric cell with its anode connected to the negative electric line and its cathode connected to the positive electric line, and an electric fuse arranged in series to the electric cell, the electric cells being configured to deliver a nominal current when discharging, the electric fuse having a breaking capacity corresponding substantially to the nominal current, so that, when totally or at least partially discharged, the electric cells are each protected from a polarity reversal caused by a forced current driven through it by the other protected electric cell.
According to the disclosure, the protected electric cells make it possible to avoid thermal runaway and short-circuit of the electric cells, and thus irretrievable internal damages of the electric cells and thus of the distress beacon.
Thanks to the by-bass diode and the electric fuse arranged respectively in parallel and in series, it is possible to avoid damages caused by a polarity reversal of the electric cells. The by-pass diode allows protecting the electric cells from excessive electrical stress, by rerouting a forced current being driven through itself, instead of through the electric cells.
Thus, a distress beacon comprising an electric cell assembly comprising protected electric cells according to the disclosure can be protected from a polarity reversal caused by another of the protected electric cells connected in series, which drives a forced current through it.
Thus, the distress beacon powered by an electric cell assembly comprising at least two protected electric cells can be effectively protected from damages, especially from damages by fire and possibly explosion, due to overheating of the electric cells, caused by thermal runaway, itself caused by polarity reversal. The distress beacon powered by an electric cell assembly comprising at least two protected electric cells according to the disclosure thus can reliably be powered, and critical damages of the surroundings of the distress beacon, such as an aircraft in which the beacon is located, may be avoided.
It should also be noted that, while significantly increasing the safety of the electric cell operation, the protected electric cells can provide high performances at nominal current in operating condition, as well in continuous mode as in burst mode with short repetition times between bursts. Also, risks of short-circuits are significantly reduced by the presence of the electric fuse connected in series the electric cell.
Advantageous and convenient features of the distress beacon are described below.
The maximum current limit in forward operation of the diode is substantially twice the nominal current.
The reverse current of the diode is comprised between 1 nanoamperes and 100 nanoamperes, preferably of approximately 20 nanoamperes.
The diode is a Schottky diode.
The electric fuse is configured to open the electric circuit of the electric cell assembly when fusing.
The electric fuse is of the passive type, that is it may not be rearmed or reactivated after having fused.
The protected electric cells further comprise a printed circuit board which supports the diode and the electric fuse.
Each of the electric cell has a substantially cylindrical shape and presents two opposite terminals on its bases, and the printed circuit board has a substantially annular shape with an outer diameter corresponding substantially to an outer diameter of the substantially cylindrical shape of the electric cell, and is arranged at the level of one of the bases of the electric cell.
The printed circuit board is arranged at the level of the electric cell’s base which presents the positive terminal of the electric cell.
The electric cell’s base which presents the positive terminal of the electric cell comprises a protruding nipple, and the printed circuit board has an inner diameter corresponding substantially to the diameter of the protruding nipple. The printed circuit board comprises a metallic path at the level of the diode, and the thickness of the metallic path at the level of the diode’s anode is at least 200 micrometers.
The protected electric cell further comprises at least one protective sheath arranged at least around the electric cell and the printed circuit board, the at least one protective sheath being preferably made of heat-shrinkable plastic.
The protected electric cell comprises two protective sheaths, arranged on top of each other.
Each of the electric cells presents two opposite terminals, and the printed circuit board is arranged at the level of a first of the opposite terminals of the electric cell, and the protected electric cells further comprise at least one elongated conductive tab which connects the second of the opposite terminals to the printed circuit board.
Each of the protected electric cells further comprises at least one protective sheath arranged at least around the electric cell and the printed circuit board, the at least one protective sheath being preferably made of heat-shrinkable plastic.
Each of the protected electric cells further comprises a cover covering the printed circuit board, and comprise a first protective sheath which maintains the at least on elongated conductive tab against the electric cell and a second protective sheath which is arranged over the first protective sheath and maintains the printed circuit board and the cover against the electric cell.
The printed circuit board is arranged at the level of the positive terminal of the electric cell.
The electric cell is a lithium-based electric cell.
The electric cell is for example a Lithium Manganese Oxide (LiMnO2) electric cell or Lithium Iron Disulfide (LiFeS2) electric cell.
The electric cell assembly comprises at least one branch of protected electric cells, each branch comprising at least two protected electric cells. The electric cell assembly comprises at least two branches of protected electric cells, the branches being connected in parallel.
The electric cell assembly comprises two to four branches of protected electric cells, each branch comprising at least two protected electric cells connected in series.
In the electric cell assembly, each branch is connected between a positive supply line and a negative supply line of the electric cell assembly, and wherein each branch comprises a protection diode with its anode connected to the positive supply line and its cathode connected in series with the positive electric line of the first protected electric cells in line in said branch.
The disclosure also provides, according to a second aspect, an aircraft, preferably of the airplane type, comprising at least one distress beacon as described here above.
Brief Description of the Drawings
The description of the disclosure now continues with a detailed description of advantageous embodiments given hereinafter by way of non-limiting example and with reference to the appended drawings.
Figure 1 is a schematic perspective view of an airplane comprising two distress beacons;
Figure 2 is a schematic front view of the distress beacon shown in Figure 1 , according to an embodiment;
Figure 3 is a schematic electric circuit diagram of an electric cell assembly of the distress beacon, the electric cell assembly comprising two protected electric cells connected in series;
Figure 4 is a schematic electric circuit diagram of a protected electric cell;
Figure 5 is a schematic electric circuit diagram of an electric cell assembly comprising a plurality of protected electric cells;
Figure 6 is an exploded view of a protected electric cell according to an embodiment; Figure 7 is an experimental test result of the operation of an unprotected electric cell, comprising plots of the current, respectively voltage, respectively temperature, in the cell over time; and
Figure 8 is an experimental test result of the operation of a protected electric cell, comprising plots of the current, respectively voltage, respectively temperature, in the cell over time.
Detailed Description of example embodiments
In the following description, similar features in different embodiments are referred to with the same reference numbers.
Figure 1 schematically depicts an aircraft 1 , which here is an airplane, comprising an emergency beacon 2, and figure 2 shows a front view of the emergency beacon 2, according to an embodiment. The emergency beacon 2 is also called “Emergency Locator Transmitter” or ELT.
The emergency beacon typically may be of the so-called automatic type, arranged in the rearmost position of the aircraft, and/or of the so-called survival type, arranged in a front position of the aircraft, such as inside the pilot’s cabin. Most modern mid- and long-range airplanes comprise at least two emergency beacons, as depicted on figure 1.
The emergency beacon 2 comprises a body 3, which is designed to withstand extreme environmental conditions, as extreme heat and fire, underwater immersion, high and/or low pressures, etc. For example, the body 3 may be made from a made of a robust composite.
The emergency beacon 2 comprises a radio transmitter (not shown), also called antenna, which is enclosed in the body 3, for example at a top part 4 of the body 3. For example, the radio transmitter is configured to operate in the 406 MHz band.
The emergency beacon 2 further may comprise a visual indicator 5, such as an electronic screen and/or indicator lights such as LEDs, which are integrated into the body 3. Furthermore, the emergency beacon 2 may also comprise buttons or switches 6 allowing to arm/unarm and/or reset and/or test the beacon, among others.
The emergency beacon 2 may itself be housed in a further casing or protective shell (not shown), when placed within the aircraft to provide additional protection against the mechanical and thermal stresses occurring during an aircraft crash.
The emergency beacon 2 comprises an electric cell assembly 10, also called battery or battery pack (schematically depicted in interrupted line on figure 2), housed within the body 3, for example at bottom part 7 of the body 3.
The electric cell assembly 10 comprises a plurality of electric cells, which here are so called protected electric cells 100. More generally, the electric cell assembly 10 comprises at least two such protected electric cells 100, and may also comprise other regular electric cells, or not.
Figure 3 is a schematic, simplified circuit diagram of an electric cell assembly 10, comprising two protected electric cells 100 connected in series. Such an electric cell assembly 10 is a possible configuration of an electric battery comprising several protected electric cells 100, as it will be described later on.
In operating condition, before use for powering an electric device, both protected electric cells 100 are fully or at least partially charged, and store a certain amount of energy.
When a load is applied on the terminals of the electric cell assembly 10, the protected electric cells 100 discharge during time.
Since both protected electric cells 100 are not necessarily charged at the same level (due to different manufacturing dates and/or aging conditions, for example), full discharge not necessarily occurs at the same time, so that one of the protected electric cells 100 may be discharged whilst the other protected electric cell 100 still contains some energy.
Using known, unprotected electric cells, this may lead the electric cell which is first to be discharged into a so-called “polarity reversal” state by the other electric cell, which drives a current through the discharged electric cell. In such conditions, damages of the discharged electric cell, and thus of the electric cell assembly, is very likely.
The electric cell assembly 10 comprising protected electric cells 100 makes it possible to avoid this drawback, by protecting an electric cell 100 when fully or almost fully discharged.
To this end, turning to Figure 4 which is an electric circuit diagram of a protected electric cell 100, a protected electric cell 100 according to an embodiment is described.
As illustrated, the protected electric cell 100 comprises an electric cell 110, which is an electrochemical device that produces electricity by converting chemical energy into electrical energy through an oxidation-reduction reaction.
For the sake of illustration, the electric cell 110 may be a non-rechargeable electric cell, also called “primary battery”. For example, the electric cell 110 may be a LiMnO2 (Lithium Manganese Oxide) cell.
The characteristics of the electric cell 110 may be chosen so as to be suitable for its intended purpose, and have no incidence on the working principle of the protected electric cell 100.
For example, the electric cell 110 may be configured to have an open circuit voltage of a few Volts (V), for instance 3.1V, and to deliver a nominal current of a few Amperes (A), for instance 1.5A.
The electric cell 110 has a positive terminal and a negative terminal, denoted respectively “+” and on Figure 2. It should be noted that this convention denotes the polarity of the electric cell 110 in operating conditions, when discharging.
In addition, the protected electric cell 100 comprises a positive electric line 111 and a negative electric line 112, respectively connected to the positive terminal of the electric cell 110 and the negative terminal of the electric cell 110.
The protected electric cell 100 further comprises an electric diode 120, hereafter called diode 120, arranged in parallel to the electric cell 110. The anode of the diode 120 is connected to the negative electric line 112 and the cathode of the diode 120 is connected to the positive electric line 111. In order words, the forward direction of the diode 120 is from the negative electric line 112 towards the positive electric line 111. The diode 120 thus is a by-pass diode 120, arranged in a “by-pass” arrangement with respect to the electric cell 110.
The diode 120 may be selected so as to have a very low reverse current, even at high temperatures.
For example, the reverse current may be 100 to 1000 times less than in a regular diode which is of the order of a few tens of microamperes (pA), in other words, the reverse current may be approximately of a few nanoamperes (nA) to a few tenth of nanoamperes, for example comprised between 1 nA and 100 nA.
The use of such type of diode 120 allows to obtain very low leak current in the electric cell assembly 10, and thus a very high lifetime of the electric cell assembly 10 and thus of the distress beacon 2. For example, the lifetime of the distress beacon 2 before its replacement may be at least of 5 years.
A suitable commercially available reference for the diode 120, at the priority date and also filing date of the present application, is reference RB058LAM-60TR, provided by ROHM Semiconductor (registered trademark). Such diode features a reverse current of approximately 20 nA when under a 3V tension, at 25°C ambient temperature.
Furthermore, the diode 120 may also be selected so that its maximum current limit in forward operation is substantially twice the nominal current of the electric cell 110, for example approximately 3A when the nominal current of the electric cell 110 is approximately 1 ,5A.
The diode 120 may be a Zener diode, or preferably a Schottky diode.
The protected electric cell also comprises an electric fuse 130, hereafter also called fuse 130, arranged in series to the electric cell 110. For example, the fuse 130 is arranged on the positive electric line 111 , between the positive terminal of the electric cell 110 and the cathode of the diode 120. However, in an alternative embodiment, the fuse 130 may also be arranged on the negative electric line 112, between the negative terminal of the electric cell 110 and the anode of the diode 120
The breaking capacity of the electric fuse 130 may be substantially equal to the nominal current of the electric cell 110, preferably over the entire operating temperature range of the protected electric cell 100.
The electric fuse 130 opens the electrical circuit during melting, so that the electrical cells are systematically isolated if the current tolerated by the cells or diodes 120 is exceeded.
Preferably, the electric fuse 130 is of the passive type, that is it may not be rearmed or reactivated after having fused. Such a feature is particularly relevant in a distress beacon, where safety requirements are very demanding.
For example, suitable commercially available references for the fuse 130 at the priority date, and also filing date, of the present application is reference 046801.5NRHF, provided by Littlefuse (registered trademark).
The above reference for the diode 120 may be used with the reference for the electric fuse 130, or not.
Turning to Figure 5, an electric circuit diagram of another electric cell assembly 10 comprising a plurality of protected electric cells 100, according to an embodiment, is shown. Hereafter, the electric cell assembly is also called electric battery, or “energy pack”.
According to the illustrated embodiment, the electric battery 10 comprises several branches 210 of protected electric cells 100, numbered from 1 through n (only branches 210i, 2102, 210n-i and 210n are shown on Figure 5).
However, the battery 10 may comprise only one branch 210.
For example, a battery 10 comprising only one branch 210 may comprise three protected electric cells 100 arranged in series. When the battery 10 comprises more than one branch 210, the branches 210 are connected in parallel between a positive supply line 220 and a negative supply line 230. An electric device to be powered may be connected to the positive supply line 220 and the negative supply line 230.
A branch 210 comprises two or more protected electric cells 100 arranged in series.
In the illustrated embodiment, a branch 210 comprises two protected electric cells 100 arranged in series.
More generally, the battery 10 may comprise any combination of one or more branches 210, which comprise two or more protected electric cells 100.
For example, the battery 10 may comprise two to four branches 210 connected in parallel, each branch 210 comprising two protected electric cells 100 connected in series.
It should be noted that a branch 210 may comprise an optional protection diode 213, for protecting a branch from a reverse voltage applied on the branch 210. To this end, the cathode of the protection diode 213 may be connected to the positive supply line 220 and the anode of the protection diode 213 may be connected to the positive electric line 111 of the first protected electric cell 100 in line.
Referring now to Figure 6, a constructive example of a protected electric cell 100 is described, according to an embodiment.
The protected electric cell 100 comprises an electric cell 110 provided in a cylindrical casing in the illustrated embodiment, without being limited to such shape. For example, the electric cell 110 may be a standardized size-A electric cell.
The electric cell 110 presents two opposite terminals on the cylindrical casing’s bases. On figure 6, only the positive terminal of the electric cell 110 is shown, and comprises a protruding nipple 113. The negative terminal (not shown) is in general substantially flat.
The protected electric cell 100 further comprises a printed circuit board (PCB) 140 which supports the diode 120 and the fuse 130. The PCB 140 is preferably arranged at the level of one of the bases of the cylindrical casing of the electric cell 110. In the illustrated embodiment, the PCB 140 is arranged at the level of the electric cell’s 110 positive terminal.
According to the illustrated embodiment, the PCB 140 has a substantially circular shape, with an outer diameter corresponding substantially to an outer diameter of the cylindrical casing of the electric cell 110.
In this particular case, when arranged at the level of the electric cell’s 110 positive terminal having a protruding nipple 113, the PCB 140 has an annular shape, with an inner diameter corresponding substantially to a diameter of the protruding nipple 113.
The PCB 140 is provided with several metallic paths forming, among others, parts of the positive electric line 111 and the negative electric line 112. The thickness of the metallic paths should be dimensioned such as to obtain a sufficient thermal drain of dissipation of the diode 120. For example, the thickness may be of about 200 micrometers, especially at the level of the anode of the diode 120.
The protected electric cell 100 comprises one or more electrically conductive tabs 150a to 150c. In particular, one electrically conductive tab 150a is configured to electrically link the negative terminal of the electric cell 110 to the PCB 140. For this purpose, the electrically conductive tab 150a has an elongated form, and one end provided with a latch for connecting with the negative terminal, and one other end provided with a latch for connecting with the PCB 140.
One conductive tab 150b may be arranged so as to connected the positive terminal of the electric cell 110 to the PCB 140.
Two other conductive tabs 150c may be arranged so as to form connection terminals terminating respectively the positive electric line 111 and negative electric line 112.
The protected electric cell 100 may also comprise a cover 160, so as to protect the conductive tabs 150 and the PCB 140. The cover 160 may be substantially in the form of a circular disc, and may comprise a pin 161 cooperating with a recess 141 of the PCB 140, for positioning the cover 160 on top of the PCB 140. The cover 160 also may comprise one or more recesses 162 for accommodating the connection terminals of the protected electric cell 100 formed by the conductive tabs 150c.
Further, the protected electric cell 100 may at least comprise a first cylindrical protective sheath 170a with inner protruding edges 171 at its bases, the cylindrical protective sheath 170a being arranged around the electric cell 110, the PCB 140, the conductive tabs 150 and the cover 160. Thanks to the edges 171 , the assembly of above-mentioned components may be maintained, and protected.
The protected electric cell 100 may also comprise a second cylindrical protective sheath 170b, arranged around the first cylindrical protective sheath 170a, so as to improve maintenance and protection even further.
In particular, the first cylindrical protective sheath 170a may be configured to maintain the conductive tab 150a, which routes the negative terminal to the PCB 140, against the casing of the electric cell 110. The second cylindrical protective sheath 170b may be configured to maintain the PCB 140 and the further components, i.e., the other conductive tabs 150 and the cover 160 among others, on the electric cell 110.
The protective sheaths 170a and/or 170b may be made of heat-shrinkable plastic, which ensures a tight fit to the above-mentioned components and thus their maintenance.
The cylindrical protective sheaths 170a and 170b also thermically isolate from each other the electric cells 110 of an electric cell assembly, and thus participate to avoid thermal runaway.
Furthermore, in the arrangement described hereabove, the PCB 140 is in intimate contact with the electric cell 110, in a “monobloc” fashion. This allows to minimize the length of electric paths and thus improve the overall safety of the protected electric cell 100.
Also, the negative terminal which is redirected toward the positive terminal and the PCB 140 thanks to the conductive tab 150a allows to concentrate both terminal at the level of the positive terminal, and thus clear the negative terminal which is devoid of electronic components. This allows to form a venting zone at the level of the negative terminal, from where gases may exhaust, without damaging any electronic components. The positive terminal, that is the anode, is well protected from mechanical shocks thanks to the stacking of the PCB 140, the cover 160, and the two cylindrical protective sheaths 170a and 170b, which together form a protective casing of the anode.
Referring to Figures 7 and 8, the functioning of a protected electric cell 100 is described.
Figures 7 and 8 represent test results of both an unprotected electric cell and a protected electric cell in operating conditions and polarity reversal conditions.
For the purpose of these tests, the setup consists of an unprotected, respectively protected, electric cell connected to a four-quadrant bipolar type power supply. This type of power supply is capable of absorbing a constant current, simulating an operation under dynamic load, and capable of delivering a floating voltage under constant current, simulating an operation as if connected to a power generator, i.e., in polarity reversal conditions.
In short, this setup allows reproducing operating conditions, when the cell is under load, and polarity reversal conditions, when the cell is substantially totally discharged, and connected in series to another electric source, for example another electric cell, driving a forced current through it.
In the tests that were carried out, the discharge current of the tested cell is substantially identical to the forced current applied during polarity reversal.
The plots displayed in Figures 7 and 8 respectively show current trough the electric cell over time, voltage at the cell’s terminals over time, and temperature of the electric cell over time. Current is expressed in Amperes (A), Voltage is expressed in Volts (V), and Temperature is expressed in Degrees Celsius (°C). Time is expressed in seconds (s).
Firstly, turning to Figure 7, the operation of an unprotected electric cell is described.
At time to=Os, the cell is fully charged and delivers a discharge current of about 1.5A when connected to the load.
During operation of the cell, between to and approximately t7soo=75OOs, the voltage at the cell’s terminals drops continuously, the cell being discharged. At approximately tysoo, the cell is fully discharged and delivers no more current. Shortly after this, the cell enters in polarity reversal operation, and inverse voltage at the cell’s terminals increases quickly. This is due to the fact that a forced current is now driven by the power supply operating as a generator.
After a short time, at about t77so=775Os, the temperature of the cell, which remained below 100°C during operation, quickly increases above 300°C, until irretrievable damage of the cell.
The test of an unprotected electric cell thus shows that without protection measures, a discharged electric cell, connected in series with another electric source, for example another at least partially charged electric cell, may enter in a reversal polarity state and be destroyed in short time.
Turning to Figure 8, the operation of a protected electric cell is described.
Between time to=Os and t7ooo=7OOOs, operation of the protected electric cell in Figure 8 is similar to the operation of the unprotected electric cell in Figure 7.
However, at the time the protected electric cell is fully discharged, no polarity reversal is observed. This is due to the diode 120 which avoids polarity reversal by redirecting current through itself.
As it can be seen on Figure 8, thanks to these measures no significant temperature rise of the protected cell is observed.
It should be noted that in case of an electric cell 110 which has a high withstand to polarity reversal, i.e. which has a forced current withstand close to the nominal current, the diode 120 may be optional, since the electric cell 110 will not be damaged by forced current during polarity reversal.
As emphasized above, when a diode 120 is needed, selecting diode 120 with a low reverse current is preferred, so as to reduce loss of stored energy during nominal operation of the protected electric cell 100. Thus, thanks to simple and convenient constructive measures, an assembly comprising a protected electric cell 100 connected in series to an electric source, such as an electric cell assembly comprising at least two protected electric cells 100, may be protected efficiently from damage when an electric cell is discharged.
Electric cell assemblies with a high number of protected electric cells 100 associated in series (and also possibly in parallel) may be designed, with a very low risk of critical damage. Indeed, each protected electric cell 100 is itself protected, so that the electric cell assembly is overall protected, even against high polarity reversal voltage. In comparison, in an electric cell assembly comprising regular electric cells, the energy absorbed by a reversed cell is a function of the square of the polarity reversal tension, so that even a low number of electric cells in series lead to a high polarity reversal tension and thus to critical damage of the assembly.
More generally, besides a distress beacon, the disclosure also provides any other electric device, comprising at least one electric cell assembly with at least two protected electric cells 100, for powering it. It should be understood that the configuration of the electric cell assembly is to be chosen so as to power adequately the electric device.
It should be noted more generally that the disclosure is not limited to the examples described and represented.

Claims

1. Distress beacon (2) comprising an electric cell assembly (10) itself comprising at least two protected electric cells (100) connected in series, wherein the protected electric cells each comprise an electric cell (110) having two terminals, a positive electric line (111) and a negative electric line (112) respectively connected to the terminals of the electric cell (110), a diode (120) arranged in parallel to the electric cell (110) with its anode connected to the negative electric line (112) and its cathode connected to the positive electric line (111), and an electric fuse (130) arranged in series to the electric cell (110), the electric cells (110) being configured to deliver a nominal current when discharging, the electric fuse (130) having a breaking capacity corresponding substantially to the nominal current, so that, when totally or at least partially discharged, the electric cells (110) are each protected from a polarity reversal caused by a forced current driven through it by the other protected electric cell.
2. Distress beacon (2) as claimed in claim 1 , wherein the maximum current limit in forward operation of the diode (120) is substantially twice the nominal current.
3. Distress beacon (2) as claimed in claim 1 or 2, wherein the reverse current of the diode (120) is comprised between 1 nanoamperes and 100 nanoamperes, preferably of approximately 20 nanoamperes.
4. Distress beacon (2) as claimed in any one of claims 1 through 3, wherein the diode (120) is a Schottky diode.
5. Distress beacon (2) as claimed in any one of claims 1 through 4, wherein the electric fuse (130) is configured to open the electric circuit of the electric cell assembly when fusing.
6. Distress beacon (2) as claimed in any one of claims 1 through 5, wherein the electric fuse (130) is of the passive type, that is it may not be rearmed or reactivated after having fused.
7. Distress beacon (2) as claimed in any one of claims 1 through 6, wherein the protected electric cells (100) further comprise a printed circuit board (140) which supports the diode (120) and the electric fuse (130).
8. Distress beacon (2) as claimed in claim 7, wherein each of the electric cells (110) presents two opposite terminals, and the printed circuit board (140) is arranged at the level of a first of the opposite terminals of the electric cell (110), and the protected electric cells (100) further comprise at least one elongated conductive tab (150a) which connects the second of the opposite terminals to the printed circuit board (140).
9. Distress beacon (2) as claimed in any one of claims 7 or 8, wherein each of the protected electric cells (100) further comprises at least one protective sheath (170a, 170b) arranged at least around the electric cell (110) and the printed circuit board (140), the at least one protective sheath (170a, 170b) being preferably made of heat-shrinkable plastic.
10. Distress beacon (2) as claimed in claims 8 and 9, wherein each of the protected electric cells (100) further comprises a cover (160) covering the printed circuit board (140), and comprise a first protective sheath (170a) which maintains the at least on elongated conductive tab (150a) against the electric cell (110) and a second protective sheath (170b) which is arranged over the first protective sheath (170a) and maintains the printed circuit board (140) and the cover (160) against the electric cell (110).
11. Distress beacon (2) as claimed in any one of claims 7 through 10, wherein the printed circuit board (140) is arranged at the level of the positive terminal of the electric cell (110).
12. Distress beacon (2) as claimed in any one of claims 7 through 11 , wherein the printed circuit board (140) comprises a metallic path at the level of the diode (120), and wherein the thickness of the metallic path at the level of the diode’s (120) anode is at least 200 micrometers.
13. Distress beacon (2) as claimed in any one of claims 1 through 12, wherein the electric cell (110) is a lithium-based electric cell, and preferably a Lithium-Manganese Oxide (LiMnO2) electric cell.
14. Distress beacon (2) as claimed in any one of claims 1 through 13, wherein the electric cell assembly (10) comprises at least one branch (210) of protected electric cells (100), each branch (210) comprising at least two protected electric cells (100).
15. Distress beacon (2) as claimed in claim 14, wherein the electric cell assembly (10) comprises at least two branches (210) of protected electric cells (100), the branches (210) being connected in parallel.
16. Distress beacon (2) as claimed in claim 14, wherein the electric cell assembly (10) comprises two to four branches (210) of protected electric cells (100), each branch (210) comprising at least two protected electric cells (100) connected in series.
17. Distress beacon (2) as claimed in any one of claims 14 through 16, wherein in the electric cell assembly (10) each branch (210) is connected between a positive supply line (220) and a negative supply line (230) of the electric cell assembly, and wherein each branch (210) comprises a protection diode (213) with its anode connected to the positive supply line (220) and its cathode connected in series with the positive electric line (111) of the first protected electric cells (100) in line in said branch (210).
18. Aircraft (1), preferably of the airplane type, comprising at least one distress beacon (2) as claimed in any one of claims 1 through 17.
EP24721956.1A 2023-05-11 2024-04-23 Distress beacon comprising a protected electric cell assembly Pending EP4710401A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP23315185.1A EP4462632A1 (en) 2023-05-11 2023-05-11 Protected electric cell, electric cell assembly and electric device comprising such
PCT/EP2024/061141 WO2024231100A1 (en) 2023-05-11 2024-04-23 Distress beacon comprising a protected electric cell assembly

Publications (1)

Publication Number Publication Date
EP4710401A1 true EP4710401A1 (en) 2026-03-18

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EP23315185.1A Withdrawn EP4462632A1 (en) 2023-05-11 2023-05-11 Protected electric cell, electric cell assembly and electric device comprising such
EP24721956.1A Pending EP4710401A1 (en) 2023-05-11 2024-04-23 Distress beacon comprising a protected electric cell assembly

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EP23315185.1A Withdrawn EP4462632A1 (en) 2023-05-11 2023-05-11 Protected electric cell, electric cell assembly and electric device comprising such

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WO (1) WO2024231100A1 (en)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2842359B1 (en) * 2002-07-11 2004-08-27 Cit Alcatel IMPROVED PROTECTION DEVICE, WITH 1S CIRCUITS, FOR A BATTERY ASSEMBLY OF ELECTROCHEMICAL GENERATORS
CN106133941A (en) * 2013-11-01 2016-11-16 巴特鲁股份有限公司 The method extending battery life
CN103682488A (en) * 2013-12-17 2014-03-26 天津力神特种电源科技有限公司 Cylindrical lithium battery with protective function
US11735778B2 (en) * 2016-09-20 2023-08-22 Honeywell Limited Battery pack device with casings for multiple cells
CN109103949A (en) * 2017-06-20 2018-12-28 通用电气公司 Battery management system
CN111653695A (en) * 2020-05-29 2020-09-11 郑棚 Lithium battery refitted constant-voltage output standard lithium rechargeable battery and production method thereof

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EP4462632A1 (en) 2024-11-13

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