TWI779767B - Mobile devices and control method for extending battery life - Google Patents

Abstract

A mobile device for extending the battery life includes a plurality of battery cells, a plurality of PTC (Positive Temperature Coefficient) resistors, a plurality of switch elements, and a controller. The PTC resistors are adjacent to the battery cells, respectively. The switch elements are disposed between the battery cells. The controllers checks whether the mobile device is supplied by an external power source, and detects the temperatures of the PTC resistors. If the mobile device is supplied by the external power source and the highest temperature of the PTC resistors is greater than or equal to a threshold value, the controller will control the switch elements, such that the battery cells can operate in a parallel mode.

Description

Mobile device and control method for extending battery life

The present invention relates to a mobile device, in particular to a mobile device that can prolong battery life.

Laptops or tablet PCs usually require battery components, however, the problem of gradual battery aging occurs after prolonged use, which may cause the battery to swell or shorten its service life. In view of this, it is necessary to propose a new solution to overcome the difficulties faced by the previous technology.

In a preferred embodiment, the present invention provides a mobile device for extending battery life, selectively coupled to an external power source, and comprising: a plurality of battery cells; a plurality of positive temperature coefficient resistors respectively adjacent to the batteries cell; a plurality of switches, arranged between the battery cells; and a controller, which confirms whether the mobile device is powered by the external power supply, and detects the temperature of the positive temperature coefficient resistors; if the mobile device The device is powered by the external power supply and the maximum temperature of the positive temperature coefficient resistors is greater than or equal to a critical value, then the controller will control the switches so that the battery cells operate in a parallel mode.

In another preferred embodiment, the present invention proposes a control method for extending battery life, which includes the following steps: providing a mobile device including a plurality of battery cells, a plurality of positive temperature coefficient resistors, and a plurality of switches, wherein The positive temperature coefficient resistors are respectively adjacent to the battery cells, and the switches are arranged between the battery cells; and confirming whether the mobile device is powered by an external power source; detecting the positive temperatures The temperature of the positive temperature coefficient resistor; if the mobile device has been powered by the external power supply and the maximum temperature of the positive temperature coefficient resistor is greater than or equal to a critical value, then control the switches so that the battery cells operate at a a parallel mode; and if the mobile device is not powered by the external power source or the maximum temperature of the PTC resistors is less than the critical value, controlling the switches so that the battery cells operate in a series mode.

In order to make the purpose, features and advantages of the present invention more comprehensible, specific embodiments of the present invention are listed below, together with the accompanying drawings, for detailed description as follows.

Certain terms are used in the specification and claims to refer to particular elements. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This description and the scope of the patent application do not use the difference in name as a way to distinguish components, but use the difference in function of components as a criterion for distinguishing. The words "comprising" and "comprising" mentioned throughout the specification and scope of patent application are open-ended terms, so they should be interpreted as "including but not limited to". The term "approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and achieve the basic technical effect. In addition, the term "coupled" in this specification includes any direct and indirect electrical connection means. Therefore, if it is described that a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device, or indirectly electrically connected to the second device through other devices or connection means. Two devices.

FIG. 1 is a schematic diagram showing a mobile device (Mobile Device) 100 and an external power source (External Power Source) 190 according to an embodiment of the present invention. For example, the mobile device 100 can be a smart phone (Smart Phone), a tablet computer (Tablet Computer), or a notebook computer (Notebook Computer). As shown in Figure 1, the mobile device 100 includes a plurality of battery cells (Battery Cell) 111, 112, a plurality of positive temperature coefficient resistors (Positive Temperature Coefficient Resistor, PTC Resistor) 121, 122, a plurality of switches (Switch Element ) 131, 132, and a controller (Controller) 150. The mobile device 100 can be selectively coupled to the external power source 190 , wherein the external power source 190 is not a part of the mobile device 100 . It must be understood that although not shown in FIG. 1, the mobile device 100 may further include other components, such as: a processor (Processor), a speaker (Speaker), a touch panel (Touch Control Panel), or (and) a housing (Housing). In other embodiments, the mobile device 100 may further include more battery cells, more positive temperature coefficient resistors, and more switches.

The positive temperature coefficient resistors 121, 122 are adjacent to the battery cells 111, 112, respectively. It must be noted that the term "adjacent" or "adjacent" in this specification may mean that the distance between the corresponding two elements is less than a predetermined distance (for example: 20mm or less), and may also include that the two corresponding elements are in direct contact with each other. case (ie, the aforementioned spacing is shortened to 0). For example, the distance D1 between the PTC resistor 121 and the battery core 111 may be less than 10 mm, and the distance D2 between the PTC resistor 122 and the battery core 112 may also be less than 10 mm, but it is not limited thereto. Therefore, the PTC resistor 121 and the battery cell 111 may have almost the same temperature T1, and the PTC resistor 122 and the battery cell 112 may have almost the same temperature T2. In addition, the switches 131 , 132 are disposed between the battery cells 111 , 112 . When the temperature T1, T2 rises, the resistance values of these positive temperature coefficient resistors 121, 122 will all rise; will fall.

The controller 150 continuously monitors various states and operating parameters of the external power source 190 , the battery cells 111 , 112 , and the PTC resistors 121 , 122 . In some embodiments, the controller 150 is implemented by a gauge IC (Gauge IC), an embedded controller (Embedded Controller, EC), or a combination of the two. Specifically, the controller 150 can confirm whether the mobile device 100 is powered by the external power source 190 , and can detect the temperatures T1 and T2 of the positive temperature coefficient resistors 121 and 122 . Then, the controller 150 can find out the maximum temperature TMAX of these positive temperature coefficient resistors 121, 122 (it can be equal to the larger one of the temperatures T1, T2), and can compare this maximum temperature TMAX with a threshold value TH Compare. For example, the threshold TH can be equal to 45 degrees Celsius, but it is not limited thereto.

If the mobile device 100 has been powered by the external power supply 190 and the maximum temperature TMAX of the positive temperature coefficient resistors 121, 122 is greater than or equal to the threshold value TH, the controller 150 will control the switches 131, 132 so that the The battery cells 111 and 112 operate in a parallel mode (Parallel Mode). Conversely, if the mobile device 100 is not powered by the external power supply 190 or the maximum temperature TMAX of the positive temperature coefficient resistors 121, 122 is less than the critical value TH, the controller 150 will control the switches 131, 132 so that the The battery cells 111 and 112 operate in a series mode (Series Mode). Under this design, if the temperature of any one of the battery cells 111, 112 is too high, the controller 150 can automatically shunt a charging current from the external power source 190, thereby avoiding further damage to the corresponding battery cells in parallel mode. aging and swelling. Therefore, the proposed mobile device 100 can greatly prolong the service life of the battery cells 111 , 112 .

The following embodiments will introduce the detailed circuit and operation method of the mobile device 100 . It must be understood that these drawings and descriptions are examples only and are not intended to limit the scope of the present invention.

FIG. 2A is a schematic diagram showing a mobile device 100 coupled to an external power source 190 according to an embodiment of the present invention. In the embodiment shown in FIG. 2A , a plug (Plug) 195 of the external power supply 190 has been inserted into an interface element (Jack Element) 160 of the mobile device 100 . At this time, the plug 195 of the external power supply 190 can contact a detection pin 170 of the interface element 160 , so that the detection pin 170 can generate a low logic voltage VL.

FIG. 2B is a schematic diagram showing that the mobile device 100 is no longer coupled to the external power source 190 according to an embodiment of the present invention. In the embodiment of FIG. 2B , the plug 195 of the external power source 190 has been pulled out from the interface element 160 of the mobile device 100 . At this time, the plug 195 of the external power supply 190 is no longer in contact with the detection pin 170 of the interface element 160, so that the detection pin 170 can generate a high logic voltage VH. Therefore, by analyzing the potential level of the detection pin 170 , the controller 150 can confirm the connection status between the mobile device 100 and the external power source 190 . For example, the low logic level VL of the detection pin 170 may indicate that the mobile device 100 has been powered by the external power source 190 . On the contrary, the high logic potential VH of the detection pin 170 may indicate that the mobile device 100 is not powered by the external power source 190 .

FIG. 3 is a schematic diagram showing the display 140 of the mobile device 100 according to an embodiment of the present invention. Please refer to Figures 1 and 3 together. In the embodiment shown in FIG. 3 , the controller 150 can further detect the voltages V1 and V2 of the battery cells 111 and 112 . Then, the controller 150 can find out the minimum voltage VMIN of the battery cells 111, 112 (which can be equal to the smaller of the voltages V1, V2), and can output a battery level information BI accordingly. Under some designs, the controller 150 will not excessively overestimate the remaining power of the battery cells 111 , 112 . In some embodiments, the controller 150 can control the display 140 to display a remaining percentage 145 according to the battery level information BI (or the minimum voltage VMIN) and a relational table, but it is not limited thereto.

Minimum voltage (mV) Remaining percentage (%) Minimum voltage (mV) Remaining percentage (%) 4378 100 3840 48.27

FIG. 4A is a schematic diagram of a mobile device 400 and an external power supply 190 according to an embodiment of the present invention (serial mode). Figure 4B is a schematic diagram showing a mobile device 400 and an external power supply 190 according to an embodiment of the present invention (parallel mode Mode). In the embodiment shown in Figures 4A and 4B, the mobile device 400 has been powered by an external power source 190, wherein the mobile device 400 includes a first battery cell 411, a second battery cell 412, and a first positive temperature coefficient resistor 421 , a second positive temperature coefficient resistor 422, a first switch 431, a second switch 432, a third switch 433, and a controller (not shown). For example, each of the first switch 431 , the second switch 432 , and the third switch 433 can be a single pole double throw (Single Pole Double Throw, SPDT) switch.

A positive pole of the external power supply 190 can be coupled to a supply node NS, and a negative pole of the external power supply 190 can be coupled to a ground node NG. The first battery cell 411 has a first end and a second end, wherein the first end of the first battery cell 411 is coupled to a first node N1, and the second end of the first battery cell 411 is coupled to A second node N2. The second battery cell 412 has a first end and a second end, wherein the first end of the second battery cell 412 is coupled to a third node N3, and the second end of the second battery cell 412 is coupled to Ground node NG. The first positive temperature coefficient resistor 421 has a first end and a second end, wherein the first end of the first positive temperature coefficient resistor 421 is coupled to a fourth node N4, and the first positive temperature coefficient resistor The second end of 421 is coupled to the supply node NS. The second PTC resistor 422 has a first end and a second end, wherein the first end of the second PTC resistor 422 is coupled to a fifth node N5, and the second PTC resistor The second end of 422 is coupled to the supply node NS. The controller of the mobile device 400 can control the first switch 431, the second switch 432, and the third switch 433, so that the first battery cell 411 and the second battery cell 412 operate in a parallel mode or a series mode .

As shown in FIG. 4A, in the series mode, the first switch 431 can couple the first node N1 to the supply node NS, and the second switch 432 and the third switch 433 can jointly couple the second node N2 connected to the third node N3. At this time, a charging current IG from the external power source 190 passes through the first battery cell 411 and the second battery cell 412 at the same time.

As shown in FIG. 4B, in the parallel mode, the first switch 431 can couple the first node N1 to the fourth node N4, the second switch 432 can couple the second node N2 to the ground node NG, and The third switch 433 can couple the third node N3 to the fifth node N5. At this time, the charging current IG from the external power source 190 can be divided into a first current I1 and a second current I2 . For example, if the temperature of the second PTC resistor 422 is greater than the temperature of the first PTC resistor 421, the second current I2 will be smaller than the first current I1 (because the resistance value of the second PTC resistor 422 greater than the resistance value of the first positive temperature coefficient resistor 421). This shunt mechanism protects the battery cell with the highest temperature from further expansion and aging.

FIG. 5A is a schematic diagram of a mobile device 500 and an external power supply 190 according to an embodiment of the present invention (serial mode). FIG. 5B is a schematic diagram of a mobile device 500 and an external power supply 190 according to an embodiment of the present invention (parallel connection mode). In the embodiment shown in Figures 5A and 5B, the mobile device 500 has been powered by an external power source 190, wherein the mobile device 400 includes a first battery cell 411, a second battery cell 412, a third battery cell 413, a first battery cell A positive temperature coefficient resistor 421, a second positive temperature coefficient resistor 422, a third positive temperature coefficient resistor 423, a first switcher 431, a second switcher 432, a third switcher 433, a The fourth switch 434, a fifth switch 435, and a controller (not shown). For example, each of the first switch 431 , the second switch 432 , the third switch 433 , the fourth switch 434 , and the fifth switch 435 can be a SPDT switch.

A positive pole of the external power supply 190 can be coupled to a supply node NS, and a negative pole of the external power supply 190 can be coupled to a ground node NG. The first battery cell 411 has a first end and a second end, wherein the first end of the first battery cell 411 is coupled to a first node N1, and the second end of the first battery cell 411 is coupled to A second node N2. The second battery cell 412 has a first end and a second end, wherein the first end of the second battery cell 412 is coupled to a third node N3, and the second end of the second battery cell 412 is coupled to - A fourth node N4. The third cell 413 has a first end and a second end, wherein the first end of the third cell 413 is coupled to a fifth node N5, and the second end of the third cell 413 is coupled to Ground node NG. The first positive temperature coefficient resistor 421 has a first end and a second end, wherein the first end of the first positive temperature coefficient resistor 421 is coupled to a sixth node N6, and the first positive temperature coefficient resistor The second end of 421 is coupled to the supply node NS. The second PTC resistor 422 has a first end and a second end, wherein the first end of the second PTC resistor 422 is coupled to a seventh node N7, and the second PTC resistor The second end of 422 is coupled to the supply node NS. The third PTC resistor 423 has a first end and a second end, wherein the first end of the third PTC resistor 423 is coupled to an eighth node N8, and the third PTC resistor The second end of 423 is coupled to the supply node NS. The controller of the mobile device 400 can control the first switch 431, the second switch 432, the third switch 433, the fourth switch 434, and the fifth switch 435, so that the first battery cell 411, the second switch The battery cell 412 and the third battery cell 413 operate in a parallel mode or a series mode.

As shown in FIG. 5A, in the series mode, the first switch 431 can couple the first node N1 to the supply node NS, and the second switch 432 and the third switch 433 can jointly couple the second node N2 to the third node N3, and the fourth switch 434 and the fifth switch 435 can jointly couple the fourth node N4 to the fifth node N5. At this time, a charging current IG from the external power source 190 passes through the first battery cell 411 , the second battery cell 412 , and the third battery cell 413 at the same time.

As shown in FIG. 5B, in the parallel mode, the first switch 431 can couple the first node N1 to the sixth node N6, and the second switch 432 can couple the second node N2 to the ground node NG. The third switch 433 can couple the third node N3 to the seventh node N7, the fourth switch 434 can couple the fourth node N4 to the ground node NG, and the fifth switch 435 can couple the fifth node N5 to Eighth node N8. At this time, the charging current IG from the external power source 190 can be divided into a first current I1, a second current I2, and a third current I3. For example, if the temperature of the second PTC resistor 422 is higher than the temperature of the first PTC resistor 421 and the temperature of the third PTC resistor 423, the second current I2 will be smaller than the first current I1 and the first PTC resistor 423. Three currents I3 (because the resistance of the second PTC resistor 422 is greater than the resistance of the first PTC resistor 421 and the third PTC resistor 423 ). This shunt mechanism protects the battery cell with the highest temperature from further expansion and aging.

FIG. 6 is a flowchart showing a control method for extending battery life according to an embodiment of the present invention. The aforementioned control method includes the following steps. In step S610, provide a mobile device including a plurality of battery cells, a plurality of positive temperature coefficient resistors, and a plurality of switches, wherein the aforementioned positive temperature coefficient resistors are respectively adjacent to the aforementioned battery cells, and the aforementioned switch The device is arranged between the aforementioned battery cells. In step S620, it is determined whether the mobile device is powered by an external power source. In step S630, the temperature of the aforementioned positive temperature coefficient resistor is detected. In step S640, it is determined whether the mobile device is powered by an external power source and the maximum temperature of the aforementioned PTC resistor is greater than or equal to a threshold value. If so, in step S650, the aforementioned switch is controlled so that the aforementioned battery cells operate in a parallel mode. If not, then in step S660, the aforementioned switch is controlled so that the aforementioned battery cells operate in a series mode. It must be understood that the above steps do not need to be performed in sequence, and each feature of the embodiment shown in FIGS. 1-5 can be applied to the control method shown in FIG. 6 .

The present invention proposes a novel mobile device. Compared with the traditional technology, the present invention at least has the advantages of reducing battery expansion and prolonging battery life, so it is very suitable for various mobile communication devices.

It should be noted that none of the device parameters mentioned above are limiting conditions of the present invention. Designers can adjust these settings according to different needs. The mobile device and control method of the present invention are not limited to the states shown in FIGS. 1-6. The present invention may only include any one or multiple features of any one or multiple embodiments of Figures 1-6. In other words, not all the illustrated features must be implemented in the mobile device and the control method of the present invention at the same time.

The methods of the present invention, or specific forms or parts thereof, may exist in the form of program codes. The code may be contained in a physical medium, such as a floppy disk, compact disc, hard disk, or any other machine-readable (such as computer-readable) storage medium, or a computer program product without limitation in external form, wherein, When the program code is loaded and executed by a machine, such as a computer, the machine becomes a device for participating in the present invention. Code may also be sent via some transmission medium, such as wire or cable, optical fiber, or any type of transmission in which when the code is received, loaded, and executed by a machine, such as a computer, that machine becomes the Invented device. When implemented on a general-purpose processing unit, the code combines with the processing unit to provide a unique device that operates similarly to application-specific logic circuits.

The ordinal numbers in this specification and the scope of the patent application, such as "first", "second", "third", etc., have no sequential relationship with each other, and are only used to mark and distinguish between two The different elements of the name.

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the scope of the present invention. Anyone skilled in this art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the scope of the appended patent application.

100,400,500: mobile devices 111,112: battery cells 121,122: positive temperature coefficient resistor 131,132:Switcher 140: display 145: remaining percentage 150: Controller 160: interface components 170: Detect pin position 190: External power supply 195: plug 411: the first battery cell 412: the second battery cell 413: The third battery cell 421: The first positive temperature coefficient resistor 422: Second positive temperature coefficient resistor 423: The third positive temperature coefficient resistor 431: The first switcher 432: second switcher 433: The third switcher 434: The fourth switcher 435: fifth switcher BI: Battery Level Information D1, D2: Spacing I1: first current I2: second current I3: the third current IG: charging current N1: the first node N2: second node N3: the third node N4: the fourth node N5: fifth node N6: sixth node N7: seventh node N8: Eighth node NG: ground node NS: supply node S610, S620, S630, S640, S650, S660: steps T1, T2: temperature TH: critical value TMAX: maximum temperature V1, V2: Voltage VH: high logic potential VL: low logic potential VMIN: minimum voltage

FIG. 1 is a schematic diagram showing a mobile device and an external power supply according to an embodiment of the present invention. FIG. 2A is a schematic diagram showing a mobile device coupled to an external power source according to an embodiment of the present invention. FIG. 2B is a schematic diagram showing the mobile device according to an embodiment of the present invention when it is no longer coupled to an external power source. FIG. 3 is a schematic diagram showing a display of a mobile device according to an embodiment of the present invention. FIG. 4A is a schematic diagram showing a mobile device and an external power supply according to an embodiment of the present invention (series mode). FIG. 4B is a schematic diagram of a mobile device and an external power supply according to an embodiment of the present invention (parallel mode). FIG. 5A is a schematic diagram showing a mobile device and an external power supply according to an embodiment of the present invention (series mode). FIG. 5B is a schematic diagram of a mobile device and an external power supply according to an embodiment of the present invention (parallel mode). FIG. 6 is a flowchart showing a control method for extending battery life according to an embodiment of the present invention.

100:Mobile

111,112: battery cells

121,122: positive temperature coefficient resistor

131,132:Switcher

150: Controller

190: External power supply

BI: Battery Level Information

D1, D2: Spacing

T1, T2: temperature

TH: critical value

TMAX: maximum temperature

V1, V2: Voltage

VMIN: minimum voltage

Claims (10)

A mobile device with extended battery life selectively coupled to an external power source, comprising: a plurality of battery cells; a plurality of positive temperature coefficient resistors respectively adjacent to the cells; a plurality of switches disposed between the battery cells; and a controller, confirming whether the mobile device is powered by the external power source, and detecting the temperature of the positive temperature coefficient resistors; Wherein if the mobile device has been powered by the external power supply and the maximum temperature of the positive temperature coefficient resistors is greater than or equal to a critical value, the controller will control the switches so that the battery cells operate in a parallel model. The mobile device as described in claim 1, wherein if the mobile device is not powered by the external power supply or the maximum temperature of the positive temperature coefficient resistors is less than the critical value, the controller will control the switches so that The battery cells operate in a series mode. The mobile device as claimed in claim 1, wherein the distance between each of the battery cells and the corresponding positive temperature coefficient resistor is less than 10mm. The mobile device as claimed in claim 1, wherein the threshold is equal to 45 degrees Celsius. The mobile device as claimed in claim 1, wherein the controller further detects the minimum voltage of the battery cells, and outputs battery power information accordingly. The mobile device as claimed in claim 2, wherein the battery cell includes a first battery cell and a second battery cell, and the positive temperature coefficient resistors include a first positive temperature coefficient resistor and a second positive temperature coefficient resistor resistors, and the switches include a first switch, a second switch, and a third switch. The mobile device as described in Claim 6, wherein: The first battery cell has a first end and a second end, wherein the first end of the first battery cell is coupled to a first node, and the second end of the first battery cell is coupled to to a second node; The second battery cell has a first end and a second end, wherein the first end of the second battery cell is coupled to a third node, and the second end of the second battery cell is coupled to to a ground node; The first positive temperature coefficient resistor has a first terminal and a second terminal, wherein the first terminal of the first positive temperature coefficient resistor is coupled to a fourth node, and the first positive temperature coefficient resistor The second end of is coupled to a supply node; The second PTC resistor has a first terminal and a second terminal, wherein the first terminal of the second PTC resistor is coupled to a fifth node, and the second PTC resistor The second terminal of is coupled to the supply node; In the parallel mode, the first switch couples the first node to the fourth node, the second switch couples the second node to the ground node, and the third switch couples the first three nodes are coupled to the fifth node; In the series mode, the first switch couples the first node to the supply node, and the second switch and the third switch couple the second node to the third node. The mobile device as claimed in claim 2, wherein the battery cell includes a first battery cell, a second battery cell, and a third battery cell, and the positive temperature coefficient resistors include a first positive temperature coefficient resistor , a second positive temperature coefficient resistor, and a third positive temperature coefficient resistor, and the switches include a first switch, a second switch, a third switch, and a fourth switch, and a fifth switcher. The mobile device as described in Claim 8, wherein: The first battery cell has a first end and a second end, wherein the first end of the first battery cell is coupled to a first node, and the second end of the first battery cell is coupled to to a second node; The second battery cell has a first end and a second end, wherein the first end of the second battery cell is coupled to a third node, and the second end of the second battery cell is coupled to to a fourth node; The third battery cell has a first end and a second end, wherein the first end of the third battery cell is coupled to a fifth node, and the second end of the third battery cell is coupled to to a ground node; The first positive temperature coefficient resistor has a first end and a second end, wherein the first end of the first positive temperature coefficient resistor is coupled to a sixth node, and the first positive temperature coefficient resistor The second end of is coupled to a supply node; The second PTC resistor has a first terminal and a second terminal, wherein the first terminal of the second PTC resistor is coupled to a seventh node, and the second PTC resistor The second terminal of is coupled to the supply node; The third PTC resistor has a first terminal and a second terminal, wherein the first terminal of the third PTC resistor is coupled to an eighth node, and the third PTC resistor The second terminal of is coupled to the supply node; In the parallel mode, the first switch couples the first node to the sixth node, the second switch couples the second node to the ground node, the third switch couples the third node is coupled to the seventh node, the fourth switch is coupled to the fourth node to the ground node, and the fifth switch is coupled to the fifth node to the eighth node; In the series mode, the first switch couples the first node to the supply node, the second switch and the third switch couple the second node to the third node, and the first Four switches and the fifth switch couple the fourth node to the fifth node. A control method for extending battery life, comprising the following steps: Provides a mobile device comprising a plurality of battery cells, a plurality of positive temperature coefficient resistors, and a plurality of switches, wherein the positive temperature coefficient resistors are respectively adjacent to the battery cells, and the switches are disposed on between the cells; and Confirm whether the mobile device is powered by an external power source; Detect the temperature of the positive temperature coefficient resistors; If the mobile device is powered by the external power supply and the maximum temperature of the PTC resistors is greater than or equal to a critical value, controlling the switches so that the battery cells operate in a parallel mode; and If the mobile device is not powered by the external power supply or the maximum temperature of the positive temperature coefficient resistors is less than the critical value, the switches are controlled so that the battery cells operate in a series mode.

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