12V lithium iron phosphate battery pack and low-voltage repair circuit and repair method thereof

Abstract

According to the 12V lithium iron phosphate battery pack and the low-voltage repair circuit and method thereof, the repair circuit mention is that the voltage decoy unit is matched with the external power supply to obtain stable working voltage, and the constant-current charging unit realizes constant-current and voltage-limiting charging, so that low-voltage batteries are prevented from being damaged by overcurrent and overvoltage, the safety of the charging process is guaranteed, and the service life of the battery pack is prolonged. The charging switch unit dynamically controls on-off of a charging loop according to battery voltage, automatic control of starting when needed and stopping after reaching the standard is achieved, manual intervention is not needed, automatic switching of charging starting and stopping is achieved based on switch control logic of a voltage threshold value, manual operation cost is reduced, and by means of double switch control and a current limiting mechanism, the charging efficiency is improved. Charging parameters are accurately controlled, the low-voltage battery is prevented from being damaged due to improper charging, and the repair success rate is increased.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of lithium battery repair, in particular to a 12V lithium iron phosphate battery pack and a low-voltage repair circuit and method thereof. BACKGROUND

[0002] With enterprises, households and mobile power users seeking lighter, smarter, safer and longer life energy solutions, 12V lithium batteries have rapidly become the preferred energy choice. The demand for 12V energy is growing from telecom systems to smart home appliances, mobile power sources for cars, solar energy storage, golf carts, yachts and backup power. In new energy application scenarios, 12V lithium iron phosphate battery packs are often used to replace traditional lead-acid batteries due to their environmental protection and long service life. Unlike lead-acid batteries, lithium iron phosphate battery packs must be equipped with a BMS (battery management system) protection board to ensure safe use, and the BMS protection board has a minimum starting voltage threshold.

[0003] In actual use, due to poor maintenance and management or long-term storage, the voltage of the lithium battery pack will gradually decrease, and when the voltage is lower than the minimum starting voltage of the BMS protection board, the BMS protection board will stop working, resulting in the lithium battery pack being unable to be charged in a conventional manner.

[0004] In the prior art, to solve the problem that the lithium battery pack cannot be charged in a conventional manner, the lithium battery pack is usually disassembled, and the internal cells are charged separately. Ordinary users cannot operate it by themselves, which brings great inconvenience to users. SUMMARY

[0005] The technical problem to be solved by the present application is that in the prior art, to solve the problem that the lithium battery pack cannot be charged in a conventional manner, the lithium battery pack is usually disassembled, and the internal cells are charged separately. Ordinary users cannot operate it by themselves, which brings great inconvenience to users.

[0006] To solve the above technical problems or at least partially solve the above technical problems, the present application provides a 12V lithium iron phosphate battery pack and a low-voltage repair circuit and method thereof.

[0007] In a first aspect, the application discloses a low-voltage repair circuit for a 12V lithium iron phosphate battery pack, which comprises a voltage deception unit, a constant-current charging unit and a charging switch unit, and the constant-current charging unit is connected to the voltage deception unit and the charging switch unit. The voltage deception unit obtains an external power supply, the constant-current charging unit charges a low-voltage battery, and the charging switch unit controls the constant-current charging unit to charge or stop charging the low-voltage battery according to the output power supply voltage value of the low-voltage battery.

[0008] Preferably, the voltage deception unit comprises an interface subunit, a deception subunit, and a detection resistance subunit, the interface subunit is connected with the deception subunit, and the detection resistance subunit is connected with the interface subunit and the deception subunit respectively.

[0009] Preferably, the constant current charging unit comprises a voltage stabilizing subunit, a first switch subunit, and a first output terminal, the voltage stabilizing subunit is connected with the first switch subunit and the first output terminal respectively, and the first output terminal charges the low-voltage battery.

[0010] Preferably, the constant current charging unit comprises a first resistance, and the first resistance is connected with the first end and the second end of the first switch subunit respectively.

[0011] Preferably, the charging switch unit comprises a second switch subunit, a first input terminal, a second input terminal, and a third switch subunit, the third switch subunit is connected with the second switch subunit and the first resistance respectively, and the second switch subunit is connected with the first input terminal and the second input terminal respectively.

[0012] Preferably, the first end of the second switch subunit inputs a voltage lower than 0.7V, and the second switch subunit is turned on.

[0013] Preferably, the gate of the third switch subunit inputs a voltage lower than 0.4V, and the third switch subunit is turned on.

[0014] Preferably, the second switch subunit and the third switch subunit are turned on, and the output terminal of the voltage stabilizing subunit charges the battery. The second switch subunit and the third switch subunit are turned off, the first switch subunit is turned on, and the output terminal of the voltage stabilizing subunit stops charging the battery.

[0015] In the second aspect, the application discloses a 12V lithium iron phosphate battery pack, which comprises the 12V lithium iron phosphate battery pack low-voltage repair circuit, a BMS unit and a battery.

[0016] In the third aspect, the application discloses a low-voltage repair method of a 12V lithium iron phosphate battery pack, which is suitable for the 12V lithium iron phosphate battery pack. The charging switch unit detects that the output voltage value of the battery is lower than a first threshold value, the charging switch unit outputs a constant current charging signal, and the constant current charging unit is controlled to charge the battery with constant current. When the output voltage value of the battery is higher than or equal to the first threshold value, the charging switch unit stops outputting the constant current charging signal, the constant current charging unit is controlled to stop charging the battery with constant current, and the battery is charged by the BMS unit.

[0017] The above technical solutions provided by the application have the following advantages compared with the prior art: The 12V lithium iron phosphate battery pack, the low-voltage repair circuit and the repair method provided by the application have the following advantages.

[0018] Further, each subunit in the circuit is modularly designed and can be directly integrated into the BMS circuit board without additional external devices, thereby simplifying the circuit structure.

[0019] The 12V lithium iron phosphate battery pack, the low-voltage repair circuit and the repair method provided by the application have the following advantages.

[0020] Further, a small number of electronic components and circuits are added to the BMS circuit board to realize the function of charging the lithium iron phosphate battery pack with a voltage as low as 0.4V without disassembling the battery pack or returning it to the factory for repair.

[0021] The repair method refers to that when the battery pack is in a low voltage state, the BMS stops charging the battery pack, the charging switch sub-unit detects that the battery output voltage value is lower than the first threshold value, the charging switch unit outputs a start constant current charging signal, controls the constant current charging unit to start, and performs constant current repair charging for the battery, when it is detected that the battery output voltage value is higher than or equal to the first threshold value, the charging switch unit outputs a stop constant current charging signal, controls the constant current charging unit to stop repair charging, and switches to a normal charging mode dominated by the BMS unit until the battery is fully charged. The repair start and stop conditions are set based on the battery voltage threshold value, so that the repair circuit is started only when the battery needs it, invalid work is avoided, the repair mode based on the constant current charging quickly supplements the power of the low-voltage battery, shortens the repair time, improves the user experience, and does not need to disassemble the battery pack or return to the factory for maintenance. The repair can be completed through the repair circuit and method provided by the battery pack, which greatly reduces the user's maintenance cost and time cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings incorporated into the specification and constituting a part of the specification show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0024] Figure 1 A circuit diagram of a 12V lithium iron phosphate battery pack low voltage repair circuit provided by the present application; Figure 2 A circuit diagram of a voltage deception unit of a 12V lithium iron phosphate battery pack low voltage repair circuit provided by the present application; Figure 3 A circuit diagram of a constant current charging unit of a 12V lithium iron phosphate battery pack low voltage repair circuit provided by the present application; Figure 4 A circuit diagram of a charging switch unit of a 12V lithium iron phosphate battery pack low voltage repair circuit provided by the present application; Figure 5 A structure module diagram of a 12V lithium iron phosphate battery pack provided by the present application.

[0025] Explanation of reference signs: 100, 12V lithium iron phosphate battery pack low voltage repair circuit; 200, 12V lithium iron phosphate battery pack; 300, BMS unit; 400, battery; 10, voltage deception unit; 11, interface subunit; 12, deception subunit; 13, detection resistance subunit; 20, constant current charging unit; 21, voltage stabilization subunit; 22, first output terminal; 23, first resistance; 30, charging switch unit; 31, first input terminal; 32, second input terminal. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below with reference to the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0027] In a first aspect, referring to Figures 1-4 The present application discloses a 12V lithium iron phosphate battery pack low-voltage repair circuit 100, which comprises a voltage deception unit 10, a constant current charging unit 20, and a charging switch unit 30. The constant current charging unit 20 is connected to the voltage deception unit 10 and the charging switch unit 30, respectively. The voltage deception unit 10 obtains an external power supply. The constant current charging unit 20 charges a low-voltage battery 400. The charging switch unit 30 controls the constant current charging unit 20 to charge or stop charging the low-voltage battery 400 according to the output power supply voltage value of the low-voltage battery 400.

[0028] Specifically, the voltage deception unit 10 matches the external power supply to obtain a stable working voltage. The constant current charging unit 20 realizes constant current and voltage limiting charging to avoid overcurrent and overvoltage damage to the low-voltage battery 400, ensuring the safety of the charging process. The charging switch unit 30 dynamically controls the on-off of the charging circuit according to the voltage of the battery 400, realizes automatic control of starting when needed and stopping after reaching the standard, and does not require manual intervention. The switching control logic based on the voltage threshold realizes automatic switching of charging start and stop, reduces manual operation cost, accurately controls charging parameters through a double switching control and current limiting mechanism, avoids damage to the low-voltage battery 400 due to improper charging, and improves the repair success rate.

[0029] Further, the various subunit modules in the circuit are modularly designed and can be directly integrated into the BMS circuit board without the need for additional external devices, simplifying the circuit structure.

[0030] The voltage deception unit 10 comprises an interface subunit 11, a deception subunit 12, and a detection resistance subunit 13. The interface subunit 11 is connected to the deception subunit 12. The detection resistance subunit 13 is connected to the interface subunit 11 and the deception subunit 12, respectively.

[0031] Specifically, the interface sub-unit 11 includes a TYPE-C interface, by accessing the corresponding charger, accessing the external power supply, the deception sub-unit 12 includes a chip U2, the chip model is CH221K, the fourth end of U2 is connected with the B12 end and the A5 end of the TYPE-C interface, the fifth end of U2 is connected with the B12 end and the B5 end of the TYPE-C interface, the A9 end of the TYPE-C interface outputs the corresponding power supply, and outputs the 15V power supply to the constant current charging unit 20. The detection resistance sub-unit 13 includes resistors R2 and R3, the resistor R2 is connected with the fourth end of U2 and the A5 end of the TYPE-C interface respectively, and the resistor R3 is connected with the fifth end of U2 and the B5 end of the TYPE-C interface respectively. The charger detection resistor R2 and the resistor R3 output the 15V power supply to the interface sub-unit 11.

[0032] The constant current charging unit 20 includes a voltage stabilizing sub-unit 21, a first switch sub-unit Q1, a first output terminal 22, and a first resistor 23. The voltage stabilizing sub-unit 21 is connected with the first switch sub-unit Q1 and the first output terminal 22 respectively, the first output terminal 22 charges the low-voltage battery 400, and the first resistor 23 is connected with the first end and the second end of the first switch sub-unit Q1 respectively.

[0033] Specifically, the first output terminal 22 is connected with the battery 400, and the first output terminal 22 charges the low-voltage battery 400. The first end of the voltage stabilizing sub-unit 21 is connected with the first switch sub-unit Q1, the second end is connected with the first output terminal 22, and the third end is connected with the interface sub-unit 11. The third end of the first switch sub-unit Q1 is connected with the first end of the voltage stabilizing sub-unit 21, the output end of the charging switch unit 30 is connected with the first end of the first switch sub-unit Q1, the output end of the charging switch unit 30 outputs the voltage which changes with the voltage value of the battery 400 detected by it, which causes the voltage applied to the first resistor 23 to change, affecting the conduction of the first switch sub-unit Q1, and then affecting the input voltage of the first end of the voltage stabilizing sub-unit 21, so that the output voltage of the voltage stabilizing sub-unit 21 changes. The voltage stabilizing sub-unit 21 converts the 15V power supply output by the voltage deception sub-unit 12 into a 12.6V power supply, outputs from the second end to the first output terminal 22, and charges the low-voltage battery 400, thereby avoiding the BMS protection board and directly charging the low-voltage battery 400, so that the low-voltage battery 400 recovers from the low-voltage state, thereby achieving the purpose of repairing the battery 400.

[0034] Among them, the voltage stabilizing sub-unit 21 includes a chip U1, and the model of U1 is LM317. The first switch sub-unit Q1 is a triode, and the model is MMBT5551.

[0035] It can be understood that the voltage stabilizer unit 21 takes the voltage difference between its first end and second end as a reference, detects the charging current in series with the first resistor 23, and converts the current signal into a voltage feedback signal through the first switch sub-unit Q1. When the charging current changes, the voltage drop across the first resistor 23 changes accordingly, thereby adjusting the conduction degree of the first switch sub-unit Q1, dynamically changing the voltage at the first end of the voltage stabilizer unit 21, and ultimately stabilizing the charging current through the closed-loop mechanism of current sampling, feedback regulation, and voltage adjustment. The charging current is about 0.5A, realizing the constant current function. At the same time, the maximum output voltage of the voltage stabilizer unit 21 is set to 12.6V through the selection of peripheral resistors, and the auxiliary voltage limiting mechanism of overvoltage, overcurrent, feedback, and voltage reduction is used to reduce the voltage to about 12.3V through the Schottky diode D1, thereby achieving the safety charging effect of limiting voltage and constant current.

[0036] The charging switch unit 30 includes a second switch sub-unit Q2, a first input terminal 31, a second input terminal 32, and a third switch sub-unit Q3. The third switch sub-unit Q3 is connected to the second switch sub-unit Q2 and the first resistor 23, respectively. The second switch sub-unit Q2 is connected to the first input terminal 31 and the second input terminal 32, respectively.

[0037] Specifically, the second end of the second switch sub-unit Q2 is connected to the second input terminal 32, the first end is connected to the first input terminal 31, and the third end is connected to the third switch sub-unit Q3. The second end of the second switch sub-unit Q2 inputs the voltage after the voltage reduction processing by the BMS protection board. The minimum voltage of the low-voltage battery 400 is 0.4V, and the voltage range inputted by the second end is 0.4V-3.3V.

[0038] When the battery 400 does not need to be charged, the input voltage of the first input terminal 31 is 3.3V, and the input voltage of the second input terminal 32 is 3.3V. When the battery 400 is in low power and needs to be charged, the input voltage of the first input terminal 31 is 0V, and the input voltage of the second input terminal 32 is lower than 3.3V. The input voltage of the first end of the second switch sub-unit Q2 is lower than 0.7V, and the second switch sub-unit Q2 is turned on. The gate input voltage of the third switch sub-unit Q3 is lower than 0.4V, and the third switch sub-unit Q3 is turned on. When the second switch sub-unit Q2 and the third switch sub-unit Q3 are turned on, the output end of the voltage stabilizer unit 21 charges the battery 400. When the second switch sub-unit Q2 and the third switch sub-unit Q3 are turned off, the first switch sub-unit Q1 is turned on, and the output end of the voltage stabilizer unit 21 stops charging the battery 400.

[0039] Among them, the second switch sub-unit Q2 adopts a triode with the model number MMBT5401, and the third switch sub-unit Q3 adopts an NMOS tube with the model number CRMLTU3400A.

[0040] Working process of the repair circuit: After the external USBPD charger accesses the Type-C interface of the voltage deception unit 10, the chip U1 communicates with the charger to switch the output of 15V voltage to supply power to the voltage stabilizing subunit 21 of the constant current charging unit 20. At this time, because the voltage of the battery 400 is too low, the BMS protection board is not started, the input voltage of the second switch subunit Q2 of the charging switch unit 30 is lower than 0.7V and is turned on, thereby making the gate voltage of the third switch subunit Q3 be turned on to turn on the charging loop. Then, the voltage stabilizing subunit 21 takes the fixed voltage difference of 1.25V between the first end and the second end as the reference, detects the charging current through the first resistor 23, forms a closed-loop feedback regulation with the first switch subunit Q1, and can stably output about 0.5A constant current. At the same time, the maximum output voltage is limited to 12.6V through peripheral resistance setting and feedback regulation, and is reduced to 12.3V through the Schottky diode D1 to charge the low-voltage battery 400. When the voltage of the battery 400 is raised by one stable voltage (such as the starting voltage 4V of the protection board), the BMS protection board is started and outputs a 3.3V control signal to the first input terminal 31, so that the input voltage of the second switch subunit Q2 is higher than 0.7V and is cut off, the gate voltage of the third switch subunit Q3 is lower than 0.4V and is also cut off, the charging loop is disconnected, the voltage stabilizing subunit 21 stops outputting current to the battery 400, the repair charging is completed, and the conventional charging dominated by the BMS is switched.

[0041] In the second aspect, referring to Figure 5 The application discloses a 12V lithium iron phosphate battery pack 200, which comprises the 12V lithium iron phosphate battery pack low-voltage repair circuit 100, the BMS unit 300 and the battery 400.

[0042] Specifically, the battery 400 body is electrically connected with the low-voltage repair circuit and the BMS unit, the BMS unit is signal-connected with the low-voltage repair circuit, voltage detection and control signal transmission are realized, the BMS unit detects the voltage of the battery 400 body in real time, the low-voltage repair circuit is responsible for repair charging in a low-voltage state, and the BMS unit dominates charging management in a conventional state.

[0043] It can be understood that the BMS unit detects the battery 400 body voltage in real time, the low voltage repair circuit is responsible for repairing charging in a low voltage state, and the BMS unit is responsible for charging management in a normal state. The problem that the low voltage battery 400 (such as the voltage as low as 0.4V) cannot be charged through the conventional BMS is solved, the conventional charging function is retained, the battery 400 voltage is monitored in real time through the BMS unit, accurate control signals are provided for the low voltage repair circuit, accurate judgment of the repair opportunity and the stop opportunity is ensured, the BMS unit and the repair circuit work cooperatively, the safety of the low voltage repair process is ensured, the overcharge and overdischarge protection function of the battery 400 group in the conventional use is maintained, and the overall reliability of the battery 400 group is improved.

[0044] Further, a small amount of electronic component circuits are added on the BMS circuit board to realize the function of charging the lithium iron phosphate battery 400 group with a voltage as low as 0.4V without disassembling the battery 400 group or returning to the factory for repair, the charger uses a common USBPD protocol charger, and the user can also operate, thereby reducing the maintenance cost.

[0045] In a third aspect, the application discloses a low voltage repair method of a 12V lithium iron phosphate battery group 200, which is suitable for the 12V lithium iron phosphate battery 400 group 200, and specifically comprises the following steps. Step S1: The BMS unit 300 detects that the output voltage value of the battery 400 is lower than a first threshold value, the charging switch unit 30 outputs a start constant current charging signal, and the constant current charging unit 20 is controlled to perform constant current charging on the battery 400. Step S2: When the output voltage value of the battery 400 is higher than or equal to the first threshold value, the charging switch unit 30 outputs a stop constant current charging signal, the constant current charging unit 20 is controlled to stop constant current charging on the battery 400, and the battery 400 is charged through the BMS unit 300.

[0046] Specifically, in step S1, the BMS unit collects the output voltage value of the battery 400 group in real time. When the voltage is detected to be lower than the first threshold value (4V), it is determined that the battery 400 is in a low-voltage repairable state. At this time, the BMS does not output a control signal, the voltage at the first input terminal 31 of the charging switch unit 30 is 0V, and the charging switch unit 30 receives the state signal of the BMS unit 300 and outputs a start constant current charging signal to make the input voltage of the second switch subunit Q2 lower than 0.7V to turn on, thereby providing voltage for the gate of the third switch subunit Q3 to meet the on condition of the third switch subunit Q3, and turn on the charging circuit of the constant current charging unit 20 and the battery 400 group. The voltage stabilizing subunit 21 of the constant current charging unit 20 starts to work, and takes 1.25V fixed voltage difference between the first end and the second end inside as the reference, detects the charging current through the first resistor 23, forms a closed loop feedback regulation with the first switch subunit Q1, stabilizes the output of 0.5A constant current, and limits the output voltage to 12.6V. After being reduced to 12.3V by the Schottky diode D1, it continuously supplies power to the low-voltage battery 400. Even if the voltage of the battery 400 is as low as 0.4V, the charging process can be started through this flow, covering most low-voltage failure scenarios, triggering the repair charging process of the low-voltage battery 400, solving the problem that the conventional charging method fails due to the low voltage of the battery 400 and the inability of the BMS to start, without manual intervention. The voltage state is automatically detected and triggered by the BMS, which is suitable for user scenarios without professional operation. Through the constant current and voltage limiting mechanism, safe charging current and voltage are provided for the low-voltage battery 400, the battery 400 cell is prevented from being damaged by large current impact, and the constant current 0.5A charging can prevent the low-voltage battery 400 from bearing excessive current, and the voltage limiting design prevents overvoltage charging, thereby improving the safety of the repair process.

[0047] Specifically, in step S2, as the constant current charging continues, the battery 400 group voltage gradually recovers, and when the BMS detects that the battery 400 output voltage is higher than or equal to the first threshold value (4V), it is determined that the battery 400 has met the normal charging conditions, and the BMS outputs a 3.3V control signal to the second input terminal 32 of the charging switch unit 30. After receiving the signal, the charging switch unit 30 outputs a stop constant current charging signal, so that the input voltage of the second switch subunit Q2 rises to 3.3V and no longer meets the conduction condition, and the second switch subunit Q2 is cut off. After the second switch subunit Q2 is cut off, the gate voltage of the third switch subunit Q3 is lower than 0.4V and is cut off, disconnecting the charging circuit of the constant current charging unit 20 and the battery 400 group. The voltage stabilizing subunit 21 of the constant current charging unit 20 stops outputting due to the disconnection of the circuit, and the repair charging process is terminated. The battery 400 group automatically switches to the normal charging mode dominated by the BMS unit, and the BMS controls the charging process according to the normal charging logic until the battery 400 is fully charged. The explicit threshold value ensures that the battery 400 only receives repair charging in a low voltage state, accurately terminates repair charging and switches to normal charging, avoids overcharging of the battery 400 caused by continuous operation of the repair circuit, and the switching process between repair charging and normal charging does not require manual operation. The circuit switching is completed instantly and does not affect the continuity of the battery 400 charging, realizing seamless connection from repair mode to normal mode, ensuring that the subsequent charging process of the battery 400 meets the standard charging specification, prolonging the service life of the battery 400, and switching between repair circuit charging and normal circuit charging can avoid unnecessary load on the battery 400 caused by long-term operation of the repair circuit. The normal charging mode is more suitable for the charging needs of the battery 400 near full charge state, reducing the risk of overcharging.

[0048] Specifically, when the battery 400 group is in a low voltage state and the BMS stops charging the battery 400 group, the charging switch subunit detects that the battery 400 output voltage value is lower than the first threshold value, the charging switch unit 30 outputs a start constant current charging signal, controls the constant current charging unit 20 to start, and performs constant current repair charging for the battery 400. When it is detected that the battery 400 output voltage value is higher than or equal to the first threshold value, the charging switch unit 30 outputs a stop constant current charging signal to control the constant current charging unit 20 to stop repair charging and switch to the normal charging mode dominated by the BMS unit until the battery 400 is fully charged. Based on the battery 400 voltage threshold value, the repair start and stop conditions are set to ensure that the repair circuit is only started when the battery 400 needs it, avoiding invalid work. Based on the repair method of constant current charging, the low voltage battery 400 is quickly charged, the repair time is shortened, and the user experience is improved. There is no need to disassemble the battery 400 group or return to the factory for repair. The repair can be completed through the self-repair circuit and method of the battery 400 group, greatly reducing the user's repair cost and time cost.

[0049] It can be understood that after the external USBPD charger accesses the Type-C interface of the repair circuit, the voltage deception unit 10 triggers the charger to output 15V working voltage through protocol matching to power the constant current charging unit 20, at this time, because the voltage of the battery 400 is lower than the BMS starting threshold, the BMS is in a dormant state, the BMS outputs a 0V signal to the first input terminal 31, so that the second switch subunit Q2 and the third switch subunit Q3 of the charging switch unit 30 meet the conduction condition, the charging circuit is connected, and the constant current charging unit 20 immediately charges the low-voltage battery 400 in the mode of 0.5A constant current and 12.3V voltage limit. With the continuous charging, the voltage of the battery 400 gradually rises, and when the voltage reaches the stop threshold of 11V, the BMS is woken up and outputs a 3.3V control signal to the first input terminal 31, which triggers the second switch subunit Q2 and the third switch subunit Q3 of the charging switch unit 30 to be cut off, the repair charging circuit is disconnected, the constant current charging unit 20 stops charging the battery 400, and then switches to the BMS-dominated normal charging mode.

[0050] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0051] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0052] In addition, the terms "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0053] In the present application, unless specifically defined otherwise, the terms "mounting", "connected", "connecting", "fixed", "fixedly connected" and the like should be construed in a broad sense, for example, they can be connected, or detachably connected, or integrated; they can be mechanical connection, or electrical connection; they can be directly connected, or indirectly connected through an intermediate medium; they can be internal communication of two elements or interaction between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0054] In the present application, unless specifically defined otherwise, "on" or "under" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "over" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Under", "below" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0055] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present application.

[0056] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, any modifications and variations of the present application, which are within the scope of the claims of the present application and their equivalent technologies, are intended to be included in the present application.

[0057] The above is a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A 12V lithium iron phosphate battery pack low voltage repair circuit, characterized in that, The low-voltage repair circuit comprises a voltage deception unit, a constant-current charging unit and a charging switch unit. The voltage deception unit obtains an external power supply, the constant-current charging unit charges a low-voltage battery, and the charging switch unit controls the constant-current charging unit to charge or stop charging the low-voltage battery according to an output power supply voltage value of the low-voltage battery.

2. The circuit of claim 1, wherein, The voltage deception unit comprises an interface subunit, a deception subunit and a detection resistance subunit.

3. The circuit of claim 1, wherein, The constant-current charging unit comprises a voltage stabilizing subunit, a first switch subunit and a first output terminal.

4. The circuit of claim 1, wherein, The constant-current charging unit comprises a first resistance, and the first resistance is connected to the first end and the second end of the first switch subunit.

5. The circuit of claim 1, wherein, The charging switch unit comprises a second switch subunit, a first input terminal, a second input terminal and a third switch subunit.

6. The circuit of claim 1, wherein, The first end of the second switch subunit inputs a voltage lower than 0.7V, and the second switch subunit is turned on.

7. The circuit of claim 1, wherein, The gate of the third switch subunit inputs a voltage lower than 0.4V, and the third switch subunit is turned on.

8. The circuit of claim 1, wherein, When the second switch subunit and the third switch subunit are turned on, the output terminal of the voltage stabilizing subunit charges the battery. When the second switch subunit and the third switch subunit are turned off, the first switch subunit is turned on, and the output terminal of the voltage stabilizing subunit stops charging the battery.

9. A 12V lithium iron phosphate battery pack characterized in that, The low-voltage repair circuit, the BMS unit and the battery are connected.

10. A low voltage recovery method for 12V LiFePO4 battery pack, suitable for 12V LiFePO4 battery pack as claimed in claim 9, wherein, Specifically, When the output voltage value of the battery is lower than the first threshold value, the charging switch unit outputs a start constant-current charging signal to control the constant-current charging unit to charge the battery with constant current. When the output voltage value of the battery is higher than or equal to the first threshold value, the charging switch unit outputs a stop constant-current charging signal to control the constant-current charging unit to stop charging the battery with constant current, and the BMS unit charges the battery.

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