Battery charging and discharging protection circuit

Abstract

The utility model relates to the technical field of battery charging and discharging, and discloses a battery charging and discharging protection circuit, which comprises an anode end B +, a cathode end B-, an anode interface P +, a cathode interface P-and a control unit of a battery pack, the anode interface P + is connected with the anode end B +, and a discharging switch and a charging switch are connected in series between the cathode interface P-and the cathode end B-. An equalization circuit and a sampling filter circuit are arranged between the positive electrode end B + and the negative electrode end B-of the battery pack and the control unit, the power supply end of the control unit is connected with the positive electrode end B +, and the control unit is further connected with a temperature detection circuit used for collecting the temperature of the battery pack and an overcurrent detection circuit used for collecting the magnitude of current in the charging and discharging process of the battery pack. And an anti-reverse connection circuit for preventing current from flowing from the positive electrode interface P + to the negative electrode interface P-is arranged between the positive electrode interface P + and the negative electrode interface P-. The charging and discharging safety of the battery pack is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery charging and discharging technical field, specifically relates to a battery charging and discharging protection circuit. BACKGROUND

[0002] The application field of rechargeable battery involves a wide range, including traffic power supply, power storage power supply, mobile communication power supply, new energy storage power supply and the like. However, if the battery is not protected during use, abnormal phenomena such as overcharging, overdischarging and overtemperature will occur, thereby causing damage to the battery and endangering the normal use of electrified products. Therefore, how to avoid the above three abnormal phenomena to better maintain the working state of the battery is an urgent problem to be solved. SUMMARY

[0003] The utility model provides a kind of battery charging and discharging protection circuit, so that battery assembly can be applied in safer, more reliable environment, guarantee the stability of battery assembly.

[0004] The utility model realizes by the following technical scheme:

[0005] A kind of battery charging and discharging protection circuit, the circuit includes the positive terminal B+ of battery pack, negative terminal B-, positive pole interface P+, negative pole interface P- and control unit, the positive pole interface P+ is connected with the positive terminal B+, discharge switch and charging switch are connected in series between the negative pole interface P- and negative terminal B-, the positive terminal B+ and negative terminal B- of the battery pack are provided with equalizing circuit and sampling filter circuit between the control unit, and the power supply end of the control unit is connected with the positive terminal B+, the control unit is also connected with the temperature detection circuit for collecting the temperature of the battery pack and the overcurrent detection circuit for collecting the current size in the charging and discharging process of the battery pack, the positive pole interface P+, negative pole interface P- between being provided with the anti-reverse connection circuit for preventing current from the positive pole interface P+ to the negative pole interface P-.

[0006] As optimization, the battery pack includes 4 batteries connected in series.

[0007] As optimization, the sampling filter circuit comprises a fourteenth resistor R14, an eighth resistor R8, a tenth resistor R10, a twelfth resistor R12, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5, wherein the first end of the fourteenth resistor R14, the first end of the eighth resistor R8, the first end of the tenth resistor R10 and the first end of the twelfth resistor R12 are respectively connected to the positive poles of the four batteries through the pin row J1, the second end of the fourteenth resistor R14, the second end of the eighth resistor R8, the second end of the tenth resistor R10 and the second end of the twelfth resistor R12 are respectively connected to the four battery positive pole connection pins of the control unit, the negative terminal B- is grounded, the first end of the second capacitor C2, the first end of the third capacitor C3, the first end of the fourth capacitor C4 and the first end of the fifth capacitor C5 are respectively connected to the second end of the twelfth resistor R12, the second end of the tenth resistor R10, the second end of the eighth resistor R8 and the second end of the fourteenth resistor R14, and the second end of the second capacitor C2, the second end of the third capacitor C3, the second end of the fourth capacitor C4 and the second end of the fifth capacitor C5 are grounded.

[0008] As optimization, the equalization circuit comprises a first transistor Q1, a second transistor Q2, a third transistor Q3 and a fourth transistor Q4, wherein,

[0009] the emitter of the first transistor Q1 is connected to the first end of the twelfth resistor R12, the base of the first transistor Q1 is connected to the second end of the twelfth resistor R12 through the series connection of a thirteenth resistor R13, and the collector of the first transistor Q1 is grounded through the series connection of a fourth resistor R4;

[0010] the emitter of the second transistor Q2 is connected to the first end of the tenth resistor R10, the base of the second transistor Q2 is connected to the second end of the tenth resistor R10 through the series connection of an eleventh resistor R11, and the collector of the second transistor Q2 is connected to the first end of the twelfth resistor R12 through the series connection of a third resistor R3;

[0011] the emitter of the third transistor Q3 is connected to the first end of the eighth resistor R8, the base of the third transistor Q3 is connected to the second end of the eighth resistor R8 through the series connection of a ninth resistor R9, and the collector of the third transistor Q3 is connected to the first end of the tenth resistor R10 through the series connection of a second resistor R2;

[0012] the emitter of the fourth transistor Q4 is connected to the first end of the fourteenth resistor R14, the base of the fourth transistor Q4 is connected to the second end of the fourteenth resistor R14 through the series connection of a seventh resistor R7, and the collector of the fourth transistor Q4 is connected to the first end of the eighth resistor R8 through the series connection of a first resistor R1.

[0013] As optimization, the overcurrent detection circuit comprises the nineteenth resistor R19, the thirty-second resistor R32, the eighth capacitor C8 and the fifteenth resistor R15, the first end of the nineteenth resistor R19 and the first end of the eighth capacitor C8 are connected to the overcurrent sampling pin of the control unit, the second end of the eighth capacitor C8 is grounded, the second end of the nineteenth resistor R19 is grounded through the series connection of the thirty-second resistor R32, the first end of the fifteenth resistor R15 is connected to the overcurrent detection ground pin of the control unit, and the second end of the fifteenth resistor R15 is grounded.

[0014] As optimization, the overcurrent detection circuit comprises the nineteenth resistor R19, the thirty-second resistor R32, the eighth capacitor C8 and the fifteenth resistor R15, the first end of the nineteenth resistor R19 and the first end of the eighth capacitor C8 are connected to the overcurrent sampling pin of the control unit, the second end of the eighth capacitor C8 is grounded, the second end of the nineteenth resistor R19 is grounded through the series connection of the thirty-second resistor R32, the first end of the fifteenth resistor R15 is connected to the overcurrent detection ground pin of the control unit, and the second end of the fifteenth resistor R15 is grounded.

[0015] As optimization, the temperature detection circuit comprises the twenty-seventh resistor R27, the twenty-sixth resistor R26, the twenty-fifth resistor R25 and the first thermistor NTC1, wherein the first end of the twenty-seventh resistor R27, the first end of the twenty-sixth resistor R26 and the first end of the twenty-fifth resistor R25 are respectively connected to the discharge over-temperature detection pin, the charging over-temperature detection pin and the low-temperature detection pin of the control unit, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are commonly connected to the first pin of the second thermistor NTC2, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are commonly connected to the second pin of the first thermistor NTC1 in series connection, and the second pin of the second thermistor NTC2 is grounded.

[0016] As optimization, the discharge switch comprises the fourth mos transistor U4, the drain of the fourth mos transistor U4 is connected to the negative terminal B-, the source of the fourth mos transistor U4 is connected to the negative interface P- through the series connection of the twenty-fourth resistor R24 and the thirty-third resistor R33, and the gate of the fourth mos transistor U4 is connected to the discharge protection output pin of the control unit in series connection with the twenty-third resistor R23.

[0017] The charging switch comprises a second MOS tube U2, the drain electrode of the second MOS tube U2 is connected with the negative electrode interface P-, the source electrode of the second MOS tube U2 is connected with the source electrode of the fourth MOS tube U4, the gate electrode of the second MOS tube U2 is connected with the drain electrode of the second MOS tube U2 in series with the twenty-eighth resistor R28, and the gate electrode of the second MOS tube U2 is also connected with the emitter electrode of the fifth triode Q5 through the second diode D2 in series, wherein the negative electrode of the second diode is connected with the gate electrode of the second MOS tube, the base electrode of the fifth triode Q5 is connected with the ground in series with the eighteenth resistor R18, and the collector electrode of the fifth triode Q5 is connected with the charging protection output pin of the control unit in series with the twenty-second resistor R22.

[0018] As optimization, the anti-reverse connection circuit comprises a third diode D3, the positive electrode of the third diode D3 is connected with the negative electrode interface P-, and the negative electrode of the third diode D3 is connected with the positive electrode interface P+.

[0019] As optimization, the control unit is a control chip of the CW1244 series.

[0020] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0021] In the utility model, the voltage of each battery is balanced in the battery pack charging and discharging process through the equalizing circuit, the voltage of each battery is collected through the sampling filter circuit, the sampled voltage signal is filtered to inhibit the noise interference of the sampling signal, the temperature of the battery pack in the charging and discharging process is detected through the temperature detection circuit, the battery pack damage caused by the too high temperature of the battery pack in the charging and discharging process is avoided, the control unit controls the opening or closing of the charging switch and the discharging switch through the detection signals of the equalizing circuit, the sampling filter circuit and the temperature detection circuit, and therefore the safety of the charging and discharging of the battery pack is guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings described herein are used to provide further understanding of the embodiments of the utility model and form part of the application and do not constitute limitation to the embodiments of the utility model.

[0023] Figure 1 It is a module connection schematic view of the battery charging and discharging protection circuit.

[0024] Figure 2 It is a specific circuit diagram of the equalizing circuit in the battery charging and discharging protection circuit.

[0025] Figure 3 It is a specific circuit diagram of the equalizing circuit in the battery charging and discharging protection circuit.

[0026] The attached diagram shows the markings and corresponding component names:

[0027] 1-Control unit, 2-Temperature detection circuit, 3-Overcurrent detection circuit, 4-Sampling and filtering circuit, 5-Equalization circuit, 6-Battery pack, 7-Discharge switch, 8-Charging switch. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0029] This embodiment 1 provides a battery charge and discharge protection circuit, such as Figures 1-2 As shown, the circuit includes a positive terminal B+, a negative terminal B-, a positive interface P+, ​​a negative interface P-, and a control unit 1. The positive interface P+ is connected to the positive terminal B+. A discharge switch 7 and a charging switch 8 are connected in series between the negative interface P- and the negative terminal B-. An equalization circuit 5 and a sampling filter circuit 4 are provided between the positive terminal B+ and the negative terminal B- of the battery pack and the control unit 1. The power supply terminal of the control unit 1 is connected to the positive terminal B+. The control unit 1 is also connected to a temperature detection circuit 2 for collecting the temperature of the battery pack and an overcurrent detection circuit 3 for collecting the current during the charging and discharging of the battery pack. A reverse connection protection circuit is provided between the positive interface P+ and the negative interface P- to prevent current from flowing from the positive interface P+ to the negative interface P-.

[0030] In some embodiments, the battery pack comprises four batteries connected in series.

[0031] It should be noted that the four batteries connected in series are connected with the positive terminal of one battery to the negative terminal of another battery, and the four batteries are connected in series to form a battery pack 6.

[0032] The power supply of control unit 1 is directly powered by battery pack 6, saving the cost of powering control unit 1 through other power sources.

[0033] The equalization circuit 5 will equalize the voltage of each battery during the charging and discharging process of the battery pack to prevent the voltage difference between the batteries from being too large.

[0034] The sampling and filtering circuit 4 is used to collect the voltage of each battery and filter the sampled voltage signal to suppress noise interference in the sampled signal.

[0035] The temperature detection circuit 2 is used to detect the temperature of the battery pack 6 during the charging and discharging process, so as to avoid the damage of the battery pack 6 caused by the high temperature of the battery pack 6 during the charging and discharging process.

[0036] The control unit 1 controls the opening or closing of the charging switch 8 and the discharging switch 7 through the detection signals of the equalization circuit 5, the sampling filter circuit 4 and the temperature detection circuit 2.

[0037] The main function of the reverse connection prevention circuit is to prevent the current from flowing from the positive interface P+ to the negative interface P-.

[0038] In some embodiments, the control unit 1 is a control chip of the CW1244 series, such as the control chip U1 in Figure 2

[0039] In some embodiments, the sampling filter circuit 4 includes a fourteenth resistor R14, an eighth resistor R8, a tenth resistor R10, a twelfth resistor R12, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5, wherein the first end of the fourteenth resistor R14, the first end of the eighth resistor R8, the first end of the tenth resistor R10 and the first end of the twelfth resistor R12 are respectively connected to the positive poles of the four batteries through the pin row J1, the second end of the fourteenth resistor R14, the second end of the eighth resistor R8, the second end of the tenth resistor R10 and the second end of the twelfth resistor R12 are respectively connected to the four battery positive pole connection pins of the control unit 1, the negative end B- is grounded, the first end of the second capacitor C2, the first end of the third capacitor C3, the first end of the fourth capacitor C4 and the first end of the fifth capacitor C5 are respectively connected to the second end of the twelfth resistor R12, the second end of the tenth resistor R10, the second end of the eighth resistor R8 and the second end of the fourteenth resistor R14, and the second end of the second capacitor C2, the second end of the third capacitor C3, the second end of the fourth capacitor C4 and the second end of the fifth capacitor C5 are grounded.

[0040] In some embodiments, the equalization circuit 5 includes a first triode Q1, a second triode Q2, a third triode Q3 and a fourth triode Q4, wherein,

[0041] the emitter of the first triode Q1 is connected to the first end of the twelfth resistor R12, the base of the first triode Q1 is connected to the second end of the twelfth resistor R12 through the series connection of the thirteenth resistor R13, and the collector of the first triode Q1 is grounded through the series connection of the fourth resistor R4;

[0042] ​The emitter of the second triode Q2 is connected with the first end of the tenth resistor R10, the base of the second triode Q2 is connected with the second end of the tenth resistor R10 through the series connection of the eleventh resistor R11, and the collector of the second triode Q2 is connected with the first end of the twelfth resistor R12 through the series connection of the third resistor R3;

[0043] The emitter of the third triode Q3 is connected with the first end of the eighth resistor R8, the base of the third triode Q3 is connected with the second end of the eighth resistor R8 through the series connection of the ninth resistor R9, and the collector of the third triode Q3 is connected with the first end of the tenth resistor R10 through the series connection of the second resistor R2;

[0044] The emitter of the fourth triode Q4 is connected with the first end of the fourteenth resistor R14, the base of the fourth triode Q4 is connected with the second end of the fourteenth resistor R14 through the series connection of the seventh resistor R7, and the collector of the fourth triode Q4 is connected with the first end of the eighth resistor R8 through the series connection of the first resistor R1.

[0045] In some embodiments, the overcurrent detection circuit 3 comprises a nineteenth resistor R19, a thirty-second resistor R32, an eighth capacitor C8 and a fifteenth resistor R15, the first end of the nineteenth resistor R19 and the first end of the eighth capacitor C8 are connected with the overcurrent sampling pin of the control unit 1, the second end of the eighth capacitor C8 is grounded, the second end of the nineteenth resistor R19 is grounded through the series connection of the thirty-second resistor R32, and the first end of the fifteenth resistor R15 is connected with the overcurrent detection ground pin of the control unit 1, and the second end of the fifteenth resistor R15 is grounded.

[0046] In some embodiments, the overcurrent detection circuit 3 comprises a nineteenth resistor R19, a thirty-second resistor R32, an eighth capacitor C8 and a sixteenth resistor R16, the first end of the sixteenth resistor R16 is connected with the overcurrent detection ground pin of the control unit 1, and the second end of the sixteenth resistor R16 is grounded.

[0047] It should be noted that two overcurrent sampling pins are provided, which correspond to the 12th pin and the 13th pin of the control chip U1. Figure 2 The fifteenth resistor R15 and the sixteenth resistor R16 can be provided only one or simultaneously, when only one of the fifteenth resistor R15 or the sixteenth resistor R16 is provided, the overcurrent sampling pin without the resistor can be empty, as a backup overcurrent sampling pin.

[0048] In some embodiments, the temperature detection circuit 2 comprises a twenty-seventh resistor R27, a twenty-sixth resistor R26, a twenty-fifth resistor R25 and a first thermistor NTC1, wherein the first end of the twenty-seventh resistor R27, the first end of the twenty-sixth resistor R26 and the first end of the twenty-fifth resistor R25 are connected to the discharge over-temperature detection pin, the charging over-temperature detection pin and the low-temperature detection pin of the control unit 1 respectively, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are connected to the first pin of a second thermistor NTC2 in common, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are connected to the second pin of the second thermistor NTC2 in common through the first thermistor NTC1 in series, and the second pin of the second thermistor NTC2 is grounded.

[0049] In some embodiments, the discharge switch 7 comprises a fourth mos tube U4, the drain of the fourth mos tube U4 is connected to the negative terminal B-, the source of the fourth mos tube U4 is connected to the negative interface P- through the twenty-fourth resistor R24 and the thirty-third resistor R33 in series, and the gate of the fourth mos tube U4 is connected to the discharge protection output pin of the control unit 1 through the twenty-third resistor R23 in series.

[0050] The charging switch 8 comprises a second mos tube U2, the drain of the second mos tube U2 is connected to the negative interface P-, the source of the second mos tube U2 is connected to the source of the fourth mos tube U4, the gate of the second mos tube U2 is connected to the drain of the second mos tube U2 through the twenty-eighth resistor R28 in series, and the gate of the second mos tube U2 is also connected to the emitter of the fifth triode Q5 through the second diode D2 in series, wherein the negative electrode of the second diode is connected to the gate of the second mos tube, the base of the fifth triode Q5 is grounded through the eighteenth resistor R18 in series, and the collector of the fifth triode Q5 is connected to the charging protection output pin of the control unit 1 through the twenty-second resistor R22 in series.

[0051] In some embodiments, the reverse connection prevention circuit comprises a third diode D3, the positive electrode of the third diode D3 is connected to the negative interface P-, and the negative electrode of the third diode D3 is connected to the positive interface P+.

[0052] In this way, the current can be prevented from directly flowing from the positive interface P+ to the negative interface P- during charging.

[0053] The above specific embodiments explain the purpose, technical scheme and beneficial effects of the present application in further detail, and it should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A battery charge and discharge protection circuit, said circuit comprising a positive terminal B+, a negative terminal B- of a battery pack, a positive interface P+, a negative interface P- and a control unit, characterized in that, The positive electrode interface P+ is connected with the positive electrode terminal B+, the discharge switch and the charge switch are connected in series between the negative electrode interface P- and the negative electrode terminal B-, the positive electrode terminal B+ and the negative electrode terminal B- of the battery pack are provided with the equalization circuit and the sampling filter circuit between the control unit, the power supply terminal of the control unit is connected with the positive electrode terminal B+, the control unit is also connected with the temperature detection circuit for collecting the temperature of the battery pack and the overcurrent detection circuit for collecting the current size in the charging and discharging process of the battery pack, and the anti-reverse connection circuit for preventing the current from flowing from the positive electrode interface P+ to the negative electrode interface P- is arranged between the positive electrode interface P+ and the negative electrode interface P-.

2. The battery charge and discharge protection circuit according to claim 1, wherein The battery pack comprises four batteries connected in series.

3. The battery charge and discharge protection circuit according to claim 2, wherein, The sampling filter circuit comprises a fourteenth resistor R14, an eighth resistor R8, a tenth resistor R10, a twelfth resistor R12, a second capacitor C2, a third capacitor C3, a fourth capacitor C4 and a fifth capacitor C5, wherein the first end of the fourteenth resistor R14, the first end of the eighth resistor R8, the first end of the tenth resistor R10 and the first end of the twelfth resistor R12 are respectively connected with the positive electrodes of the four batteries through the pin row J1, the second end of the fourteenth resistor R14, the second end of the eighth resistor R8, the second end of the tenth resistor R10 and the second end of the twelfth resistor R12 are respectively connected with the four battery positive electrode connection pins of the control unit, the negative electrode terminal B- is grounded, the first end of the second capacitor C2, the first end of the third capacitor C3, the first end of the fourth capacitor C4 and the first end of the fifth capacitor C5 are respectively connected with the second end of the twelfth resistor R12, the second end of the tenth resistor R10, the second end of the eighth resistor R8 and the second end of the fourteenth resistor R14, and the second end of the second capacitor C2, the second end of the third capacitor C3, the second end of the fourth capacitor C4 and the second end of the fifth capacitor C5 are grounded.

4. The battery charge and discharge protection circuit according to claim 3, wherein, The equalization circuit comprises a first transistor Q1, a second transistor Q2, a third transistor Q3 and a fourth transistor Q4, wherein, the emitter of the first transistor Q1 is connected with the first end of the twelfth resistor R12, the base of the first transistor Q1 is connected with the second end of the twelfth resistor R12 through the series connection of the thirteenth resistor R13, and the collector of the first transistor Q1 is grounded through the series connection of the fourth resistor R4; the emitter of the second transistor Q2 is connected with the first end of the tenth resistor R10, the base of the second transistor Q2 is connected with the second end of the tenth resistor R10 through the series connection of the eleventh resistor R11, and the collector of the second transistor Q2 is connected with the first end of the twelfth resistor R12 through the series connection of the third resistor R3; the emitter of the third transistor Q3 is connected with the first end of the eighth resistor R8, the base of the third transistor Q3 is connected with the second end of the eighth resistor R8 through the series connection of the ninth resistor R9, and the collector of the third transistor Q3 is connected with the first end of the tenth resistor R10 through the series connection of the second resistor R2; the emitter of the fourth transistor Q4 is connected with the second end of the twelfth resistor R12, the base of the fourth transistor Q4 is connected with the first end of the tenth resistor R10 through the series connection of the sixth resistor R6, and the collector of the fourth transistor Q4 is connected with the second end of the eighth resistor R8 through the series connection of the fifth resistor R5. The first end of the fourteenth resistor R14 is connected with the emitter of the fourth triode Q4, the second end of the fourteenth resistor R14 is connected with the base of the fourth triode Q4 through the series connection of the seventh resistor R7, and the first end of the eighth resistor R8 is connected with the collector of the fourth triode Q4 through the series connection of the first resistor R1.

5. The battery charge and discharge protection circuit according to claim 1, wherein, The overcurrent detection circuit comprises the nineteenth resistor R19, the thirty-second resistor R32, the eighth capacitor C8 and the fifteenth resistor R15, the first end of the nineteenth resistor R19 and the first end of the eighth capacitor C8 are connected with the overcurrent sampling pin of the control unit, the second end of the eighth capacitor C8 is grounded, the second end of the nineteenth resistor R19 is grounded through the series connection of the thirty-second resistor R32, and the first end of the fifteenth resistor R15 is connected with the overcurrent detection ground pin of the control unit, and the second end of the fifteenth resistor R15 is grounded.

6. The battery charging and discharging protection circuit according to claim 1 or 5, wherein The overcurrent detection circuit comprises the nineteenth resistor R19, the thirty-second resistor R32, the eighth capacitor C8 and the fifteenth resistor R15, the first end of the nineteenth resistor R19 and the first end of the eighth capacitor C8 are connected with the overcurrent sampling pin of the control unit, the second end of the eighth capacitor C8 is grounded, the second end of the nineteenth resistor R19 is grounded through the series connection of the thirty-second resistor R32, and the first end of the fifteenth resistor R15 is connected with the overcurrent detection ground pin of the control unit, and the second end of the fifteenth resistor R15 is grounded.

7. The battery charge and discharge protection circuit according to claim 1, wherein The temperature detection circuit comprises the twenty-seventh resistor R27, the twenty-sixth resistor R26, the twenty-fifth resistor R25 and the first thermistor NTC1, wherein the first end of the twenty-seventh resistor R27, the first end of the twenty-sixth resistor R26 and the first end of the twenty-fifth resistor R25 are connected with the discharge over-temperature detection pin, the charging over-temperature detection pin and the low-temperature detection pin of the control unit respectively, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are commonly connected with the first pin of the second thermistor NTC2, the second end of the twenty-seventh resistor R27, the second end of the twenty-sixth resistor R26 and the second end of the twenty-fifth resistor R25 are commonly connected with the first pin of the first thermistor NTC1 and connected with the second pin of the second thermistor through the series connection, and the second pin of the second thermistor NTC2 is grounded.

8. The battery charge and discharge protection circuit according to claim 1, wherein, The discharge switch comprises the fourth mos tube U4, the drain of the fourth mos tube U4 is connected with the negative electrode terminal B-, the source of the fourth mos tube U4 is connected with the negative electrode interface P- through the series connection of the twenty-fourth resistor R24 and the thirty-third resistor R33, and the gate of the fourth mos tube U4 is connected with the discharge protection output pin of the control unit through the series connection of the twenty-third resistor R23. The charging switch includes a second MOS tube U2, a drain of the second MOS tube U2 is connected with the negative pole interface P-, a source of the second MOS tube U2 is connected with a source of the fourth MOS tube U4, a gate of the second MOS tube U2 is connected with the drain of the second MOS tube U2 in series with a twenty-eighth resistance R28, and the gate of the second MOS tube U2 is also connected with an emitter of a fifth triode Q5 through a second diode D2 in series, wherein a negative pole of the second diode is connected with the gate of the second MOS tube, a base of the fifth triode Q5 is grounded in series with an eighteenth resistance R18, and a collector of the fifth triode Q5 is connected with a charging protection output pin of the control unit in series with a twenty-second resistance R22.

9. The battery charge and discharge protection circuit according to claim 1, wherein, The reverse connection prevention circuit includes a third diode D3, a positive pole of the third diode D3 is connected with the negative pole interface P-, and a negative pole of the third diode D3 is connected with the positive pole interface P+.

10. The battery charge and discharge protection circuit according to claim 1, wherein, The control unit is a control chip of the CW1244 series.

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