EP4066223A1

EP4066223A1 - Device for security systems, preferably for fire alarm systems, and management method for the power supply for such device

Info

Publication number: EP4066223A1
Application number: EP20829971.9A
Authority: EP
Inventors: Vincenzo NESTA
Original assignee: Argus Security Srl
Current assignee: Argus Security Srl
Priority date: 2019-11-29
Filing date: 2020-11-27
Publication date: 2022-10-05
Also published as: IT201900022467A1; WO2021105935A1; AU2020393191A1

Abstract

A device (1, 1A, 1B, 1C) for a security system (100), preferably a fire alarm system (100), the device (1, 1A, 1B, 1C) comprising an electrical supply unit (4) suitable to autonomously feed one or more components (6) of said device (1, 1A, 1B, 1C) and comprising a first battery (10) and a second battery (12). In particular, the first battery (10) and the second battery (12) are equal each other and, in addition, the device (1, 1A, 1B, 1C) comprises switching means (16) interacting with the two batteries (10, 12) and suitable to allow the feeding of the components (6) of the device (1, 1A, 1B, 1C) through the first battery (10) or through the second battery (12), and a control unit (18) operatively connected with the switching means (16) to actuate the first battery (10) and the second battery (12) according to a switching sequence in which the operating time (T1) of the first battery (10) is greater than the operating time (T2) of the second battery (12).

Description

DEVICE FOR SECURITY SYSTEMS, PREFERABLY FOR FIRE ALARM SYSTEMS, AND MANAGEMENT METHOD FOR THE POWER SUPPLY FOR SUCH DEVICE

DESCRIPTION

The present invention belongs to the field of security systems, in particular, of fire alarm systems.

More specifically, the invention deals with the management of the power supply involving one or more devices which form said systems.

Security systems are known which are suitable for detecting and/or signaling particular dangerous conditions, such as, for example, fire outbreaks or established fires, gas leaks etc. Such systems, first of all, have the task of detecting particular quantities and/or parameters connected to the dangerous condition and of signaling such dangerous condition in an appropriate manner. Signaling may comprise, for example, an acoustic and/or visual warning signal. In other cases, signaling may comprise sending an emergency call to the fire brigade.

Security systems of the known type conventionally comprise a main control device which communicates with one or more peripheral devices according to suitable communication protocols, in a cabled and/or wireless manner.

Peripheral devices of the known type comprise, for example, physical quantity detectors or sensors, such as, for example, heat detectors, smoke detectors, gas detectors, carbon monoxide detectors, optical detectors.

Peripheral devices may also comprise warning devices such as, for example, acoustic indicators (sirens) or visual indicators (lights, LEDs).

In some cases, the devices integrate one or more of said detection and/or signaling functions, for example, a smoke detector device with integrated acoustic warning.

Peripheral devices send and/or receive control information to/from the main control device which oversees the operation of the entire security system, such as controlling the operation of the detectors, analyzing any alarm situations and preparing any necessary actions, such as the activation of an acoustic warning or the sending of calls to the fire brigade and so on.

In alternative solutions, the peripheral device is itself set up for an autonomous operation, or stand-alone operation, which allows, for example, both the detection and the signaling of an alarm situation.

In such case, the system will be defined by a single device, the peripheral device, and does not require a main device as defined above. Devices of such type are also commercially known as detector base sounders.

Such devices consist of a detection unit comprising a sensor to which an appropriate signaling device, also known as a base sounder, is connected. According to the prior art, such devices, in particular the peripheral devices, are electrically fed by means of batteries, for example, standard lithium batteries of the CR123A or CR2032 type.

To ensure security standards, or for the CE marking of the security systems of the known type, and, in particular, fire alarm systems, the systems are designed to meet certain requirements dictated by specific regulations.

A particular aspect, dictated by such regulations, concerns the management of the power supply of such systems. In particular, some regulations dictate the requirements connected to the devices fed by autonomous energy, such as said devices equipped with a battery.

Some regulatory requirements, for example the UNI EN 54-25 standard, in points 5.3.2 and 5.3.3, impose minimum duration limits for autonomous batteries and indications relating to the low battery signal to then allow the replacement and ensure the operation of the self-powered device in a substantially continuous manner.

A particular requirement provides that the autonomously powered device is capable of generating and transmitting an error signal, or fault signal, when the end of the battery charge is approaching and which is also capable of ensuring the operation of the device for a further prefixed time interval, for example another 30 minutes in active warning conditions.

A system (or device) according to the prior art uses a main battery with a sufficient capacity to ensure the minimum duration limit required and a backup battery with a lower capacity. The device is currently fed with the main battery, the voltage of which is monitored by a control unit which detects the value thereof and any drop below a prefixed minimum charge threshold.

When the main battery reaches the minimum threshold, the control unit generates and transmits the error signal and prepares the device to be fed by the backup battery until the optimal working condition is restored with the replacement with a new main battery and a backup battery.

The use of a backup battery is indispensable, in particular, in the case of use of a main battery of the lithium type, which has a particularly rapid decay feature from the moment in which the voltage begins to decrease and the moment in which it completely discharges.

The time between the detection of the voltage decay below a prefixed threshold and the time of complete discharge is, in fact, insufficient to satisfy the residual duration requests according to the relevant regulations provided therefor, which is the reason why the use and control of a single lithium battery would be unsatisfactory.

An aspect which is particularly felt by manufacturers of devices for security systems is therefore that of creating solutions which meet the requirements of the regulations in an efficient manner.

It is the main object of the present invention, therefore, to propose an alternative solution with respect to known systems, which allows to meet the requirements of the regulations in an efficient manner.

It is another object of the present invention to provide an alternative solution with respect to the known systems, which allows to lengthen the duration of the devices for autonomously powered security systems.

It is a further object of the present invention to indicate an alternative solution with respect to equivalent systems of the known type, which allows the efficient use of lithium batteries.

Said objects are achieved by means of a device for a security system, preferably a fire alarm system, as in the accompanying claim 1 , to which reference is however made for the sake of brevity. Not only a security system, preferably a fire alarm system, comprising such device, but also a method for the management of a power supply unit of said device, contribute to obtaining the aforesaid objects, as per the respective accompanying claims.

In a first aspect thereof, the present invention relates, therefore, to a device for a security system, preferably a fire alarm system, said device comprising an electrical supply unit suitable to autonomously feed one or more components of said device and comprising a first battery and a second battery, in which said first battery and said second battery are equal each other, and in which the device comprises: switching means interacting with said two batteries, suitable to allow feeding of said one or more components of said device through said first battery or through said second battery; a control unit operatively connected with said switching means to actuate said first battery and said second battery according to a switching sequence in which the operating time of said first battery is greater than the operating time of said second battery.

The two batteries are to be considered equal each other where they preferably have the same nominal voltage, expressed in Volts, and the same capacity, expressed in mAh.

According to a preferred embodiment, the switching means comprise one or more switches.

Preferably, said one or more switches comprise a solid-state component, preferably a MOSFET, or an electromechanical switch.

In a preferred embodiment, said one or more components comprise one of the selected elements of the group consisting in a heat detector, a smoke detector, a gas detector, a carbon monoxide detector, an optical detector, a buzzer, a visual warning device.

Preferably, said switching sequence comprises several switching cycles, in which, in each switching cycle, the operating time of said first battery is greater than said operating time of said second battery. In a preferred embodiment, said operating time of said first battery is greater than said operating time of said second battery according to a predefined percentage. According to a preferred embodiment, said switching cycles repeat in the same way with reference to said operating time of said first battery and to said operating time of said second battery.

Preferably, said device comprises means for detecting the state of charge of said first battery.

In a preferred embodiment, said detection means comprise a voltage detector of said first battery.

According to a preferred embodiment of the invention, said device comprises signaling means of battery error.

Preferably, but not necessarily, said signaling means of battery error comprise visual and/or acoustic signaling means.

In a preferred embodiment, said device comprises wireless communication means for the communication with other devices.

In another aspect thereof, the present invention relates to a security system, preferably a fire alarm system, comprising a main control device and one or more peripheral devices, in which at least one of said peripheral devices is a device made as described above.

Preferably, said main control device and/or said one or more peripheral devices communicate with each other by means of wireless signals.

In a further aspect thereof, the present invention relates to a method for the management of an electrical supply unit of a device for a security system, preferably a fire alarm system, said electrical supply unit being suitable to autonomously feed one or more components of said device and comprising a first battery and a second battery equal each other, in which the method includes feeding said one more components of said device through said first battery or said second battery according to a switching sequence in which the operating time of said first battery is greater than the operating time of said second battery. According to a preferred embodiment, said switching sequence comprises several switching cycles for the alternate operation of said first battery and said second battery, in which, in each switching cycle, said operating time of said first battery is greater than said operating time of said second battery.

In a preferred embodiment, said operating time of said first battery is greater than said operating time of said second battery according to a predefined percentage. Preferably, said switching cycles repeat in the same way with reference to said operating time of said first battery and to said operating time of said second battery.

According to a preferred embodiment, the method comprises a step of detecting the state of charge of said first battery.

Preferably, when said state of charge falls below a prefixed threshold, a battery error signal is generated.

In a preferred embodiment, a step is provided of sending said battery error signal from said device to other devices.

According to a preferred embodiment, when said charge state falls below said prefixed threshold, said one more components of said device are powered only by said second battery.

Said objects and advantages will be more apparent from the description that follows, related to a preferred embodiment of the device for a security system and the relative system of the invention, given by way of indicative and non-limiting example, with reference to the appended drawings, in which:

Figure 1 shows a security system provided with more devices according to a preferred embodiment of the invention;

Figure 2 shows an exemplary diagram of a device according to a preferred embodiment of the invention;

Figure 3 shows an exemplary embodiment of a detail of the device of Figure 2 in a first operating condition;

Figure 4 shows the diagram of Figure 3 in a second operating condition;

Figure 5 shows an embodiment of the diagram of Figure 3;

Figure 6 shows the trend of driving signals for the operation of the device of Figures 3 to 5 according to a preferred embodiment;

Figure 7 shows the characteristic trend of the voltage, over time, of a battery which may be used in the device of Figure 2. The present invention has proved particularly advantageous with reference to the construction of fire alarm systems, or fire detection systems, as described in detail below.

It is however useful to point out that the present invention is not limited to such type of systems. On the contrary, the present invention finds convenient application in all cases relating to security systems which involve the use of self- powered devices in which it is necessary to ensure a charge margin which guarantees a minimum residual life of the device, for example in alarm systems. Figure 1 shows a fire alarm system 100, or fire detection system, which uses devices 1A, 1 B, 1C to implement a method according to a preferred embodiment of the present invention.

The fire alarm system 100 according to the embodiment shown in Figure 1 is a fire alarm system according to a wireless architecture, also known as a radio fire detection system.

The fire alarm system 100 preferably comprises a main control device (represented, for example by a central unit) 102, a communication unit 104 for the transmission of radio signals and a plurality of peripheral devices 1A, 1 B, 1C communicating via radio with the communication unit 104.

The main control device 102 and the communication unit 104 are preferably fed by the electrical network, while the peripheral devices 1A, 1 B, 1C, according to an aspect of the present invention, are battery-powered, or self-powered, as described in detail below.

The main control device 102 and the communication unit 104 are preferably arranged in a dedicated area/compartment, easily accessible to the operators while the peripheral devices 1A, 1 B, 1C are suitably positioned in the places/rooms to be controlled.

The main control device 102 has the function of managing and communicating with the peripheral devices 1A, 1 B, 1C by means of the communication unit 104 and preferably comprises a user interface 106 suitable for allowing access to an operator for reading or entering data relating to the operation of the system 100. The user interface 106 preferably, but not necessarily, comprises an LCD display and/or keys and/or a touch screen. The peripheral devices preferably comprise one or more detectors 1A, or physical quantity sensors, such as, for example, heat detectors, smoke detectors, gas detectors, carbon monoxide detectors, optical detectors and so on, suitable for detecting a possible risk of fire or a fire in progress and one or more warning devices, such as, for example, acoustic indicators (sirens) or visual indicators (lights, LEDs).

In preferred but not binding embodiments, such detectors 1A may comprise both one or more physical quantity sensors and a warning device integrated in the same device.

The peripheral devices further comprise, by way of preferred but not limiting example, one or more input devices 1 B, such as, for example, call point devices and possibly one or more signal repeater devices 1C, or expanders, suitable for ensuring communication between the communication unit 104 and other peripheral devices arranged in places/rooms further away with respect to the main control device 102.

The call point input devices preferably comprise a button which may be operated by an operator to generate a warning on call, i.e., the warning is not triggered by the detection of a sensor but by means of the operator pressing the button All the aforementioned peripheral devices, indicated with reference numerals 1A, 1B, 1C, are battery-powered, or self-powered, and are preferably made according to what is described below to implement the inventive concept of the present invention.

For the sake of simplicity, in the following description reference will be made generically to a device indicated with reference numeral 1 to indicate any of the peripheral devices 1A, 1 B, 1C as defined above.

According to an aspect of the present invention, the device 1 of the invention comprises an electrical supply unit 4 suitable for autonomously supplying one or more components, generically indicated with reference numeral 6 in Figure 2, of the device 1. The components 6 of the device 1 are preferably fed by the power supply line V exiting the electrical supply unit 4. The components 6 of the device 1 of the invention comprise all those parts of the device 1 which require power supply, for example the sensor element itself, the acoustic siren and more.

According to a first advantageous aspect of the invention, the device 1 comprises a first battery 10 and a second battery 12 equal each other.

The two batteries 10, 12 are to be considered equal each other where they preferably have the same nominal voltage, expressed in Volts, and the same capacity, expressed in mAh.

Preferably, the two batteries have the same chemistry, preferably two lithium batteries are used.

More preferably, the two batteries are identical and are even more preferably selected from within the same production batch. This ensures a more correct management of the power supply according to what is described below.

For example, the two batteries 10, 12 comprise two CR123A batteries (3 Volt, 1200 mAh) selected from the same production batch.

It should be noted that the expression "first battery" is generally intended as a charge accumulator, regardless of the construction technology thereof. For example, the expression "first battery" also means a battery consisting of several batteries, or a battery pack, in which the battery pack has, as a whole, a predefined nominal voltage, expressed in Volts, and a predefined capacity, expressed in mAh.

Similarly, the expression "second battery" generally means a charge accumulator, regardless of the construction technology thereof. For example, the expression "second battery" also means a battery consisting of several batteries, or a battery pack, in which the battery pack has, as a whole, a predefined nominal voltage, expressed in Volts, and a predefined capacity, expressed in mAh.

In another advantageous aspect thereof, the device 1 of the present invention comprises switching means 16 interacting with the two batteries 10, 12 and suitable to allow the feeding of the components 6 of the device 1 through the first battery 10 or through the second battery 12.

When the components 6 are fed by the first battery 10, the device 1 is in a respective first operating condition, as shown in Figure 3, while, when the components 6 are fed by the second battery 12, the device 1 is in a respective second operating condition, as shown in Figure 4.

The switching means 16 preferably comprise one or more switches 16a, 16b.

The switches 16a, 16b preferably comprise a solid-state component, more preferably a MOSFET, as shown in Figure 5.

In variant embodiments of the invention, the switching means may be made with other components, for example, with electromechanical switches.

A control unit 18 is operatively connected with the switching means 16 and allow to actuate the first battery 10 and the second battery 12 according to a switching sequence in which the operating time T1 of the first battery 10 is greater than the operating time T2 of the second battery 12.

Figure 6 shows the control signals S1 , S2 of the control unit 18 for the switching means 16, which allow to operate the first battery 10 and the second battery 12 according to a preferred switching sequence of the invention.

According to such preferred embodiment, the switching sequence comprises several switching cycles, in which, in each switching cycle, the operating time T1 of the first battery 10 is greater than the operating time T2 of the second battery 12. The switching cycles preferably repeat in the same way with reference to the operating time T1 of the first battery 10 and to the operating time T2 of the second battery 12.

Preferably but not exclusively, the operating time T1 of the first battery 10 is greater than the operating time T2 of the second battery 12 according to a predefined percentage or, in other words, within the switching cycle, the first battery 10 is operated for a percentage greater with respect to the second battery 12, for example, according to respective percentages of 60% and 40%.

Preferably, the operating times T1 , T2 of the batteries 10, 12 are of the order of magnitude of minutes, for example T1 = 15min and T2 = 12min.

Such values are preferably selected considering the capacities of the batteries 10, 12 used and/or the average consumption of the device 1 and/or the residual charge of the second battery 12 required, as better described below. Advantageously, considering that initially the two batteries 10, 12 are the same, and that inside the device 1 they feed the same components 6 substantially in the same operating conditions, and considering that the first battery 10 is active for a time longer with respect to the second battery 12, it follows that the first battery 10 is subject to a faster discharge with respect to the second battery 12. In other words, when the first battery 10 reaches a level considered to be a discharged battery level, i.e., when the state of charge falls below a prefixed threshold at a corresponding instant of time tf, the second battery 12 is still provided with a residual charge, for example, with the values of T1 = 15min and T2 = 15min mentioned above, the second battery 12 still has an approximate residual charge of 10% with respect to the total charge.

First of all, when the state of charge falls below said prefixed threshold, the device 1 of the current invention generates a battery error signal (or battery fault event). The battery fault event is preferably signaled at device level 1 , for example, by means of a light and/or acoustic signal. In an embodiment variant, the battery error signal is sent by the device 1 to the main control device (or central unit) 102 by means of the communication unit 104. The battery fault event may therefore be signaled at central unit level 102, for example by signaling on the LCD screen 106 directly visible to the operator and/or by means of an acoustic signal.

For this purpose, the device 1 comprises wireless communication means 20 for the communication with other devices, in particular with the communication unit 104. Furthermore, the battery fault event is preferably stored in the event history in the main control device (or central unit) 102 and/or the communication unit 104 and/or on a PC suitably connected by means of an RS-232 serial interface to the main control device 102 and/or to the communication unit 104.

Once the battery fault event has been duly signaled, the components 6 of the device 1 of the invention are fed only by means of the second battery 12, i.e., the device 1 is kept in the second operating condition (condition shown in Figure 6). The corresponding control signals S1 , S2 of the control unit 18 for the switching means 16 are also shown in Figure 6, in which the control signal S1 for the first battery 10 is always inactive and the control signal S2 for the second battery 12 is always active, starting from the instant of time tf.

The device 1 of the present invention remains in such second operating condition until the charge of the second battery 12 is completely exhausted, or following the intervention of an operator intervening to replace the two batteries 10, 12 and to restore the normal operation of the device 1 itself.

The maximum operating duration of the device 1 of the present invention, in the second operating configuration, obviously depends on the residual charge of the second battery 12. Such duration will depend on the choice of the operating times T1 , T2 and the division therebetween within the cycle.

Preferably, but not exclusively, the choice of the operating times T1 , T2 is made on the basis of the consumption foreseen by the components 6 of the device 1 , so that the residual charge of the second battery 12 ensures an operating time in the second operating condition for a prefixed time interval which meets the limits imposed by the regulations, for example, the UNI EN 54-25 standards, in the points 5.3.2 and 5.3.3.

Advantageously, the power supply unit 4 with two batteries 10, 12 described above and the respective method for the management of the batteries 10, 12 allow to comply with the limitations imposed by the regulations on the operating duration of self-powered devices after the error signal, or fault signal, has been generated. Furthermore, advantageously, the use of two equal batteries and the alternate operation thereof, according to what is described above, allow to extend the useful life of the device of the invention which corresponds, at most, to the sum of the duration of the two individual batteries.

According to a preferred embodiment of the invention, the determination of the low battery level occurs by means of suitable detection means 30 which allow to determine when the state of charge falls below a prefixed threshold.

Preferably, the detection means 30 comprise a voltage detector of the first battery 10.

The first battery 10 is, in such case, considered discharged when the voltage at the ends thereof drops below a prefixed threshold Vth.

By way of example, Figure 6 shows the characteristic trend of the voltage, over time, of a lithium battery of the CR123A type which feeds a load with 30mA DC, such battery being usable as the first battery 10 in the device 1 according to the invention. In this case, the threshold Vth for determining a discharged battery is preferably set at a value equal to 2.85 Volts. More preferably, a hysteresis value, according to known techniques, for example a value ± 0.02 Volt, is associated with the threshold Vth to avoid bounces in voltage readings.

By virtue of the description provided above, it is therefore understood that the device and the associated method for the management of the power supply of such device, both of which are the subject of the present invention, achieve the objects and the advantages mentioned above.

Finally, it is clear that numerous other changes may be made to the device and/or method in question, without thereby departing from the principles of novelty inherent in the inventive idea expressed herein.

Where the constructional features and techniques mentioned in the following claims are followed by reference signs or numerals, such reference signs were introduced for the sole purpose of increasing intelligibility of the claims themselves, and therefore such reference signs have no limiting effect on the interpretation of each element identified merely by way of example only by such reference signs.

Claims

1. Device (1 , 1A, 1 B, 1C) for a security system (100), preferably a fire alarm system (100), said device (1 , 1A, 1 B, 1C) comprising an electrical supply unit (4) suitable to autonomously feed one or more components (6) of said device (1 , 1A, 1 B, 1C) and comprising a first battery (10) and a second battery (12), characterized in that said first battery (10) and said second battery (12) are equal each other, and that said device (1 , 1A, 1B, 1C) comprises: switching means (16) interacting with said two batteries (10, 12) and suitable to allow feeding of said one or more components (6) of said device (1 , 1 A, 1 B, 1C) through said first battery (10) or through said second battery (12); a control unit (18) operatively connected with said switching means (16) to actuate said first battery (10) and said second battery (12) according to a switching sequence in which the operating time (T1) of said first battery (10) is greater than the operating time (T2) of said second battery (12).

2. Device (1 , 1A, 1 B, 1C) according to claim 1), characterized in that said switching means (16) comprise one or more switches (16a, 16b).

3. Device (1 , 1A, 1 B, 1C) according to claim 2), characterized in that said one or more switches (16a, 16b) comprise a solid-state component, preferably a MOSFET, or an electromechanical switch.

4. Device (1 , 1A, 1B, 1C) according to any one of the previous claims, characterized in that said one or more components (6) comprise one of the elements of the group consisting in a heat detector, a smoke detector, a gas detector, a carbon monoxide detector, an optical detector, a buzzer, a visual warning device.

5. Device (1 , 1A, 1B, 1C) according to any one of the previous claims, characterized in that said switching sequence comprises several switching cycles, wherein in each switching cycle said operating time (T1) of said first battery (10) is greater than said operating time (T2) of said second battery (12).

6. Device (1 , 1A, 1B, 1C) according to any one of the previous claims, characterized in that said operating time (T1) of said first battery (10) is greater than said operating time (T2) of said second battery (12) according to a predefined percentage.

7. Device (1 , 1A, 1 B, 1C) according to claim 5), characterized in that said switching cycles repeat in the same way with reference to said operating time (T1) of said first battery (10) and to said operating time (T2) of said second battery (12).

8. Device (1 , 1A, 1 B, 1C) according to any of the previous claims, characterized in that it comprises detection means (30) suitable to detect the state of charge of said first battery (10).

9. Device (1 , 1A, 1B, 1C) according to claim 8), characterized in that said detection means (30) comprise a voltage detector of said first battery (10).

10. Device (1 , 1A, 1 B, 1C) according to any one of the previous claims, characterized it comprises signaling means of battery error.

11. Device (1 , 1A, 1 B, 1C) according to claim 10), characterized in that said signaling means comprise visual and/or acoustic signaling means.

12. Device (1 , 1A, 1 B, 1C) according to any one of the previous claims, characterized in that it comprises wireless communication means (20) for communication with other devices.

13. Security system (100), preferably a fire alarm system, comprising a main control device (102) and one or more peripheral devices (1 , 1A, 1 B, 1C), characterized in that at least one of said peripheral devices (1 , 1A, 1 B, 1C) is a device (1 , 1 A, 1 B, 1 C) according to any one of the previous claims.

14. System according to claim 13), characterized in that said main control device (102) and/or said one or more peripheral devices (1 , 1A, 1 B, 1C) communicate each other by means of wireless signals.

15. Method for the management of an electrical supply unit (4) of a device (1, 1A, 1B, 1C) for a security system (100), preferably a fire alarm system (100), said electrical supply unit (4) being suitable to autonomously feed one or more components (6) of said device (1 , 1A, 1 B, 1C) and comprising a first battery (10) and a second battery (12) equal each other, characterized in that it comprise the operation of feeding said one more components (6) of said device (1 , 1A, 1B, 1C) through said first battery (10) or said second battery (12) according to a switching sequence in which the operating time (T1) of said first battery (10) is greater than the operating time (T2) of said second battery (12).

16. Method according to claim 15), characterized in that said switching sequence comprises several switching cycles for the alternate operation of said first battery (10) and said second battery (12), wherein in each switching cycle the operating time (T1) of said first battery (10) is greater than said operating time (T2) of said second battery (12).

17. Method according to claim 15) or 16), characterized in that said operating time (T1) of said first battery (10) is greater than said operating time (T2) of said second battery (12) according to a predefined percentage.

18. Method according to claim 16) or 17), characterized in that said switching cycles repeat in the same way with reference to said operating time (T1) of said first battery (10) and to said operating time (T2) of said second battery (12).

19. Method according to any of the claims 15) to 18), characterized in that it comprises an operation of detecting the state of charge of said first battery (10).

20. Method according to claim 19), characterized in that, when said charge state falls below a prefixed threshold (Vth), a battery error signal is generated.

21. Method according to claim 20), characterized in that said battery error signal is sent from said device (1 , 1 A, 1 B, 1 C) to other devices.

22. Method according to claim 20) or 21), characterized in that, when said charge state falls below said prefixed threshold (Vth), said one more components (6) of said device (1 , 1 A, 1 B, 1 C) are powered only by said second battery (12).