A battery low temperature protection circuit

Abstract

The utility model discloses a low temperature protection circuit for a battery, which includes: a primary protection circuit, a secondary protection circuit and a temperature protection circuit; the first end of the primary protection circuit is connected to the negative pole of the battery; the second end of the primary protection circuit is connected to the first end of the secondary protection circuit; the second end of the secondary protection circuit is connected to the negative charging end; the temperature protection circuit includes: a temperature protection chip, a thermistor, a switch device and a heating element; the temperature protection chip obtains the temperature of the environment through the thermistor, and is connected to the switch device to control the heating element to connect to the positive and negative poles of the battery. By adopting the embodiment of the utility model, while realizing low temperature protection, the battery power loss caused by continuous heating is avoided.

Description

Technical Field

[0001] The utility model relates to the field of battery protection, in particular to a battery low-temperature protection circuit. Background Art

[0002] Batteries are generally divided into lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries and lithium-ion batteries. The power output capacity of batteries in low-temperature environments is very limited, which will greatly affect the performance of the equipment in which the batteries are located. Existing technologies mainly use heating wires to heat the environment in which the batteries are located; however, the heating wire circuit may continue to increase the temperature of the environment in which the batteries are located, thereby causing battery capacity loss. Utility Model Content

[0003] The utility model provides a battery low temperature protection circuit to solve the technical problem in the prior art that the battery capacity is lost due to continuous heating of the heating wire during temperature protection.

[0004] In order to solve the above technical problems, the embodiment of the utility model provides a battery low temperature protection circuit, including: a primary protection circuit, a secondary protection circuit and a temperature protection circuit;

[0005] Wherein, the first end of the primary protection circuit is connected to the negative electrode of the battery;

[0006] The second end of the primary protection circuit is connected to the first end of the secondary protection circuit;

[0007] The second terminal of the secondary protection circuit is connected to the negative charging terminal;

[0008] The temperature protection circuit comprises: a temperature protection chip, a thermistor, a switch device and a heating element; the temperature protection chip comprises: a temperature measurement pin and an output pin;

[0009] The temperature measuring pin of the temperature protection chip is connected to the first end of the thermistor;

[0010] The second end of the thermistor is grounded;

[0011] The output pin of the temperature protection chip is connected to the control end of the switch device;

[0012] The first end of the switch device is connected to the positive electrode of the battery;

[0013] The second end of the switch device is connected to the first end of the heating element;

[0014] The second end of the heating element is connected to the negative electrode of the multi-cell battery.

[0015] In the temperature protection circuit of the utility model, the output end of the temperature protection chip is connected to the control end of the switch device, so that the switch device is controlled based on the thermistor in a situation where temperature adjustment is required to connect the heating element between the positive and negative electrodes of the battery, thereby providing temperature protection; in addition, the primary protection circuit and the secondary protection circuit are connected in series between the negative electrode and the negative charging terminal of the battery, so that when the control switch fails and the heating element is heated for a long time, the connection between the battery and the charging terminal is disconnected, thereby realizing circuit protection and avoiding battery capacity loss.

[0016] Furthermore, the switch device comprises: one of a triode, a MOS tube and a relay device.

[0017] Further, the heating element comprises: a first heating wire and a second heating wire;

[0018] Wherein, the first end of the first heating wire is the first end of the heating element;

[0019] The second end of the first heating wire is connected to the first end of the second heating wire;

[0020] The second end of the second heating wire is the second end of the heating element.

[0021] Furthermore, the temperature protection circuit further includes a first resistor, a second resistor, a first capacitor and a second capacitor;

[0022] The first end of the first resistor is connected to the positive electrode of the battery;

[0023] The second end of the first resistor is connected to the enable input pin of the temperature protection chip;

[0024] The first end of the second resistor is connected to the positive electrode of the battery;

[0025] The second end of the second resistor is connected to the battery connection pin of the temperature protection chip and the first end of the first capacitor;

[0026] The second end of the first capacitor is grounded;

[0027] The first end of the second capacitor is connected to the battery voltage detection pin of the temperature protection chip;

[0028] The second terminal of the second capacitor is grounded;

[0029] Wherein, the enable input pin of the temperature protection chip is connected to the positive electrode of the battery;

[0030] The battery voltage detection pin of the temperature protection chip is connected to the positive electrode of the battery;

[0031] The battery connection pin of the temperature protection chip is connected to the positive electrode of the battery;

[0032] The ground pin of the temperature protection chip is connected to the second end of the thermistor;

[0033] The ground pin of the temperature protection chip is grounded.

[0034] Furthermore, the primary protection circuit includes: a first battery protection chip, a first switch tube and a second switch tube; wherein the first battery protection chip includes: a discharge protection pin and a charge protection pin

[0035] The discharge protection pin of the first battery protection chip is connected to the control end of the first switch tube;

[0036] The first end of the first switch tube is the first end of the primary protection circuit;

[0037] The second end of the first switch tube is connected to the first end of the second switch tube;

[0038] The charging protection pin of the first battery protection chip is connected to the control end of the second switch tube;

[0039] The second end of the second switch tube is the second end of the primary protection circuit.

[0040] In the primary protection circuit of the utility model, the discharge protection pin and the charge protection pin are respectively connected to the control ends of the two switch tubes, so that when the battery is overcharged or over-discharged due to the temperature protection circuit, the first end and the second end of the switch tube are controlled to be disconnected, thereby disconnecting the battery from the charging end, avoiding battery capacity loss caused by the heating element or other factors.

[0041] Furthermore, the first battery protection chip further includes: a current detection voltage input pin, a positive power input pin, a negative power input pin and a test pin;

[0042] Wherein, the current detection voltage input pin of the first battery protection chip is connected to the negative electrode of the battery;

[0043] The positive power input pin of the first battery protection chip is connected to the positive electrode of the battery;

[0044] The negative power input pin of the first battery protection chip is connected to the negative electrode of the battery;

[0045] The test pin of the first battery protection chip is connected to a preset test point.

[0046] The positive power input pin and the negative power input pin of the first battery protection chip in the utility model are respectively connected to the positive and negative electrodes of the battery to monitor the positive and negative electrode voltages of the battery; when the heating element continues to heat up, the changes in the positive and negative electrode voltages of the battery are monitored, and the switch tube is controlled to be disconnected through the discharge protection pin and the charging protection pin to achieve protection and avoid loss of battery capacity.

[0047] Furthermore, the primary protection circuit further includes: a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor;

[0048] Wherein, the first end of the third capacitor is connected to the first end of the first switch tube;

[0049] The second end of the third capacitor is connected to the first end of the fourth capacitor;

[0050] The second end of the fourth capacitor is connected to the second end of the second switch tube;

[0051] The first end of the fifth capacitor is connected to the positive power input pin of the first battery protection chip;

[0052] The second end of the fifth capacitor is connected to the negative power input pin of the first battery protection chip;

[0053] The first end of the sixth capacitor is connected to the negative power input pin of the first battery protection chip;

[0054] The second end of the sixth capacitor is connected to the current detection voltage input pin of the first battery protection chip.

[0055] Furthermore, the secondary protection circuit includes: a second battery protection chip, a third switch tube and a fourth switch tube; wherein the second battery protection chip includes: a discharge protection pin and a charge protection pin

[0056] The discharge protection pin of the second battery protection chip is connected to the control end of the third switch tube;

[0057] The first end of the third switch tube is the first end of the secondary protection circuit;

[0058] The second end of the third switch tube is connected to the first end of the fourth switch tube;

[0059] The charging protection pin of the second battery protection chip is connected to the control end of the fourth switch tube;

[0060] The second end of the fourth switch tube is the second end of the secondary protection circuit.

[0061] The discharge protection pin and the charge protection pin in the secondary protection circuit of the utility model are respectively connected to the control ends of the two switch tubes, so that when the battery is overcharged or the temperature protection circuit is over-discharged and the primary protection circuit fails, the first end and the second end of the switch tube are controlled to be disconnected, so that the battery is disconnected from the charging end, avoiding battery capacity loss caused by heating elements or other factors.

[0062] Furthermore, the second battery protection chip further includes: a current detection voltage input pin, a positive power input pin, a negative power input pin, a test pin and a control function pin;

[0063] Wherein, the secondary protection circuit further includes: a sixth resistor, a seventh resistor and an eighth resistor; wherein the second battery protection chip further includes a current detection voltage input pin, a positive power input pin, a negative power input pin, a test pin and a control function pin;

[0064] The first end of the sixth resistor is connected to the positive electrode of the battery;

[0065] The second end of the sixth resistor is connected to the positive power input pin of the second battery protection chip;

[0066] The first end of the seventh resistor is connected to the control function pin of the second battery protection chip;

[0067] The second end of the seventh resistor is loaded with a preset control signal;

[0068] A first end of the eighth resistor is connected to a test pin of the second battery protection chip;

[0069] The second end of the eighth resistor is connected to the negative charging end;

[0070] The current detection voltage input pin of the second battery protection chip is connected to the negative electrode of the battery;

[0071] A negative power input pin of the second battery protection chip is grounded.

[0072] The positive power input pin and the negative power input pin of the second battery protection chip in the utility model are respectively connected to the positive electrode of the battery and the circuit ground to realize the monitoring of the positive and negative voltages of the battery; when the heating element continues to heat up, the changes in the positive and negative voltages of the battery are monitored, and the switch tube is controlled to be disconnected through the discharge protection pin and the charging protection pin to realize protection and avoid the loss of battery capacity.

[0073] Furthermore, the secondary protection circuit further includes: a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, an eleventh capacitor and a twelfth capacitor;

[0074] Wherein, the first end of the seventh capacitor is connected to the first end of the third switch tube;

[0075] The second end of the seventh capacitor is connected to the first end of the eighth capacitor;

[0076] The second end of the eighth capacitor is connected to the second end of the fourth switch tube;

[0077] The first end of the ninth capacitor is connected to the positive power input pin of the second battery protection chip;

[0078] The second end of the ninth capacitor is connected to the negative power input pin of the second battery protection chip;

[0079] The first end of the tenth capacitor is connected to the negative power input pin of the second battery protection chip;

[0080] The second end of the tenth capacitor is connected to the current detection voltage input pin of the second battery protection chip;

[0081] The first end of the eleventh capacitor is connected to the control function pin of the second battery protection chip;

[0082] The second end of the eleventh capacitor is connected to the first end of the twelfth capacitor;

[0083] The second terminal of the twelfth capacitor is grounded. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] Figure 1 A schematic diagram of the structure of an embodiment of a battery low temperature protection circuit provided by the utility model;

[0085] Figure 2 A schematic diagram of the connection relationship of an embodiment of the temperature protection chip provided by the utility model;

[0086] Figure 3 A schematic diagram of the connection relationship of an embodiment of the primary protection circuit provided by the utility model;

[0087] Figure 4 A schematic diagram of the connection relationship of an embodiment of the secondary protection circuit provided by the utility model. DETAILED DESCRIPTION

[0088] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0089] Please refer to Figure 1 , Figure 1 This is a schematic structural diagram of an embodiment of a battery low temperature protection circuit provided by the utility model, and the battery low temperature protection circuit includes: a primary protection circuit 101, a secondary protection circuit 102 and a temperature protection circuit 103;

[0090] Wherein, the first end of the primary protection circuit 101 is connected to the negative electrode B- of the battery;

[0091] The second end of the primary protection circuit 101 is connected to the first end of the secondary protection circuit 102;

[0092] The second terminal of the secondary protection circuit 102 is connected to the negative charging terminal;

[0093] The temperature protection circuit includes: a temperature protection chip U3, a thermistor RT1, a switch device Q3 and a heating element; the temperature protection chip U3 includes: a temperature measurement pin TS and an output pin KEY;

[0094] The temperature measuring pin TS of the temperature protection chip U3 is connected to the first end of the thermistor RT1;

[0095] The second end of the thermistor RT1 is grounded;

[0096] The output pin KEY of the temperature protection chip U3 is connected to the control end of the switch device Q3;

[0097] The first end of the switch device Q3 is connected to the positive electrode B+ of the battery;

[0098] The second end of the switching device Q3 is connected to the first end of the heating element;

[0099] The second end of the heating element is connected to the negative electrode B- of the battery.

[0100] In this embodiment, the output pin KEY of the temperature protection chip U3 is used to output a level signal to the control end of the switch device Q3, controlling the switch device Q3 to close or open, thereby controlling the heating element to connect to the positive and negative poles of the battery or disconnect the connection with the positive and negative poles of the battery. When the environment where the battery is located is lower than the normal operating temperature range of the battery, the temperature of the connected thermistor RT1 is detected through the temperature measurement pin TS of the temperature protection chip U3, and a level signal is output to the switch device Q3 through the output pin KEY to close the switch device Q3; when the environment where the battery is located enters the normal operating temperature range of the battery, the temperature protection chip U3 controls the switch device Q3 to open through the output pin KEY, so that the heating element is disconnected from the positive and negative poles of the battery and stops heating. When the switch device Q3 fails, the primary protection circuit and the secondary protection circuit are disconnected to avoid problems such as overcurrent caused by continuous heating of the temperature protection circuit.

[0101] Furthermore, the switch device Q3 includes: one of a triode, a MOS tube and a relay device.

[0102] In this embodiment, when the switch device Q3 is a MOS tube, especially an NMOS tube, the output pin KEY of the temperature protection chip U3 outputs a high level to the gate of the NMOS tube to control the NMOS tube to be closed or turned on, and outputs a low level to the gate of the NMOS tube to control the NMOS tube to be opened or turned off.

[0103] Further, the heating element comprises: a first heating wire L1 and a second heating wire L2;

[0104] Wherein, the first end of the first heating wire L1 is the first end of the heating element;

[0105] The second end of the first heating wire L1 is connected to the first end of the second heating wire L2;

[0106] The second end of the second heating wire L2 is the second end of the heating element.

[0107] Please refer to Figure 2 , Figure 2 A schematic diagram of the connection relationship of an embodiment of the temperature protection chip provided by the utility model. Further, the temperature protection circuit also includes a first resistor R12, a second resistor R11, a first capacitor C10 and a second capacitor C11;

[0108] The first end of the first resistor R12 is connected to the positive electrode B+ of the battery;

[0109] The second end of the first resistor R12 is connected to the enable input pin CE of the temperature protection chip U3;

[0110] A first end of the second resistor R11 is connected to the positive electrode B+ of the battery;

[0111] The second end of the second resistor R11 is connected to the battery connection pin BAT of the temperature protection chip U3 and the first end of the first capacitor C10;

[0112] The second end of the first capacitor C10 is grounded;

[0113] The first end of the second capacitor C11 is connected to the battery voltage detection pin BAT_SNS of the temperature protection chip;

[0114] The second end of the second capacitor C11 is grounded;

[0115] Wherein, the enable input pin CE of the temperature protection chip U3 is connected to the positive electrode of the battery;

[0116] The battery voltage detection pin BAT_SNS of the temperature protection chip U3 is connected to the positive electrode of the battery;

[0117] The battery connection pin BAT of the temperature protection chip U3 is connected to the positive electrode of the battery;

[0118] The ground pin VSS of the temperature protection chip U3 is connected to the second end of the thermistor RT1;

[0119] A ground pin VSS of the temperature protection chip U3 is grounded.

[0120] In this embodiment, the first resistor, the second resistor, the first capacitor and the second resistor constitute a peripheral circuit of the temperature protection chip to ensure the normal operation of the temperature protection chip and avoid the chip being unable to perform temperature protection due to faults.

[0121] For further information, please refer to Figure 3 , Figure 3 A schematic diagram of the connection relationship of an embodiment of the primary protection circuit provided by the utility model. The primary protection circuit 101 includes: a first battery protection chip U2, a first switch tube and a second switch tube; wherein the first battery protection chip U2 includes: a discharge protection pin DOUT and a charge protection pin COUT;

[0122] The discharge protection pin DOUT of the first battery protection chip U2 is connected to the control end of the first switch tube;

[0123] The first end of the first switch tube is the first end of the primary protection circuit 101;

[0124] The second end of the first switch tube is connected to the first end of the second switch tube;

[0125] The charging protection pin COUT of the first battery protection chip U2 is connected to the control end of the second switch tube;

[0126] The second end of the second switch tube is the second end of the primary protection circuit 101 .

[0127] In the primary protection circuit of the utility model, the discharge protection pin and the charge protection pin are respectively connected to the control ends of the two switch tubes, so that when the battery is overcharged or over-discharged due to the temperature protection circuit, the first end and the second end of the switch tube are controlled to be disconnected, thereby disconnecting the battery from the charging end, avoiding battery capacity loss caused by the heating element or other factors.

[0128] Furthermore, the first battery protection chip U2 further includes: a current detection voltage input pin CS, a positive power input pin VDD, a negative power input pin VSS and a test pin VM;

[0129] Wherein, the current detection voltage input pin CS of the first battery protection chip U2 is connected to the negative electrode B- of the battery;

[0130] The positive power input pin VDD of the first battery protection chip U2 is connected to the positive electrode B+ of the battery;

[0131] The negative power input pin VSS of the first battery protection chip U2 is connected to the negative electrode B- of the battery;

[0132] The test pin VM of the first battery protection chip U2 is connected to a preset test point.

[0133] The positive power input pin and the negative power input pin of the first battery protection chip in the utility model are respectively connected to the positive and negative electrodes of the battery to monitor the positive and negative electrode voltages of the battery; when the heating element continues to heat up, the changes in the positive and negative electrode voltages of the battery are monitored, and the switch tube is controlled to be disconnected through the discharge protection pin and the charging protection pin to achieve protection and avoid loss of battery capacity.

[0134] Furthermore, the primary protection circuit 101 further includes: a third capacitor C6, a fourth capacitor C5, a fifth capacitor C4, and a sixth capacitor C12;

[0135] Wherein, the first end of the third capacitor C6 is connected to the first end of the first switch tube;

[0136] The second end of the third capacitor C6 is connected to the first end of the fourth capacitor C5;

[0137] The second end of the fourth capacitor C5 is connected to the second end of the second switch tube;

[0138] The first end of the fifth capacitor C4 is connected to the positive power input pin VDD of the first battery protection chip U2;

[0139] The second end of the fifth capacitor C4 is connected to the negative power input pin VSS of the first battery protection chip U2;

[0140] The first end of the sixth capacitor C12 is connected to the negative power input pin VSS of the first battery protection chip U2;

[0141] The second end of the sixth capacitor C12 is connected to the current detection voltage input pin CS of the first battery protection chip U2.

[0142] In this embodiment, the primary protection circuit 101 further includes: a third resistor R3, a fourth resistor RS1 and a fifth resistor R4;

[0143] Wherein, the first end of the third resistor R3 is connected to the positive electrode of the battery;

[0144] The second end of the third resistor R3 is connected to the positive power input pin VDD of the first battery protection chip U2;

[0145] The first end of the fourth resistor RS1 is connected to the negative power input pin VSS of the first battery protection chip U2;

[0146] The second end of the fourth resistor RS1 is connected to the current detection voltage input pin CS of the first battery protection chip U2;

[0147] A first end of the fifth resistor R4 is connected to a test pin VM of the first battery protection chip U2;

[0148] The second end of the fifth resistor R4 is connected to the preset test point.

[0149] For further information, please refer to Figure 4 , Figure 4 A schematic diagram of the connection relationship of an embodiment of the secondary protection circuit provided by the utility model. The secondary protection circuit 102 includes: a second battery protection chip U1, a third switch tube and a fourth switch tube; wherein the second battery protection chip U1 includes: a discharge protection pin DOUT and a charge protection pin COUT;

[0150] The discharge protection pin DOUT of the second battery protection chip U1 is connected to the control end of the third switch tube;

[0151] The first end of the third switch tube is the first end of the secondary protection circuit 102;

[0152] The second end of the third switch tube is connected to the first end of the fourth switch tube;

[0153] The charging protection pin COUT of the second battery protection chip U1 is connected to the control end of the fourth switch tube;

[0154] The second end of the fourth switch tube is the second end of the secondary protection circuit 102 .

[0155] The discharge protection pin and the charge protection pin in the secondary protection circuit of the utility model are respectively connected to the control ends of the two switch tubes, so that when the battery is overcharged or the temperature protection circuit is over-discharged and the primary protection circuit fails, the first end and the second end of the switch tube are controlled to be disconnected, so that the battery is disconnected from the charging end, avoiding battery capacity loss caused by heating elements or other factors.

[0156] Furthermore, the secondary protection circuit further includes: a sixth resistor R1, a seventh resistor R13 and an eighth resistor R2; the second battery protection chip U1 further includes: a current detection voltage input pin CS, a positive power input pin VDD, a negative power input pin VSS, a test pin VM and a control function pin CNT;

[0157] Wherein, the first end of the sixth resistor R1 is connected to the positive electrode of the battery;

[0158] The second end of the sixth resistor R1 is connected to the positive power input pin VDD of the second battery protection chip U1;

[0159] The first end of the seventh resistor R13 is connected to the control function pin CNT of the second battery protection chip U1;

[0160] The second end of the seventh resistor R13 is loaded with a preset control signal;

[0161] A first end of the eighth resistor R2 is connected to a test pin VM of the second battery protection chip U1;

[0162] The second end of the eighth resistor R2 is connected to the negative charging end;

[0163] The current detection voltage input pin CS of the second battery protection chip U1 is connected to the negative electrode B- of the battery;

[0164] A negative power input pin VSS of the second battery protection chip U1 is grounded.

[0165] The positive power input pin and the negative power input pin of the second battery protection chip in the utility model are respectively connected to the positive electrode of the battery and the circuit ground to realize the monitoring of the positive and negative voltages of the battery; when the heating element continues to heat up, the changes in the positive and negative voltages of the battery are monitored, and the switch tube is controlled to be disconnected through the discharge protection pin and the charging protection pin to realize protection and avoid the loss of battery capacity.

[0166] Furthermore, the secondary protection circuit 102 further includes: a seventh capacitor C3, an eighth capacitor C2, a ninth capacitor C1, a tenth capacitor C13, an eleventh capacitor C14 and a twelfth capacitor C15;

[0167] Wherein, the first end of the seventh capacitor C3 is connected to the first end of the third switch tube;

[0168] The second end of the seventh capacitor C3 is connected to the first end of the eighth capacitor C2;

[0169] The second end of the eighth capacitor is connected to the second end of the fourth switch tube;

[0170] The first end of the ninth capacitor C1 is connected to the positive power input pin VDD of the second battery protection chip U1;

[0171] The second end of the ninth capacitor C1 is connected to the negative power input pin VSS of the second battery protection chip U1;

[0172] The first end of the tenth capacitor C13 is connected to the negative power input pin VSS of the second battery protection chip U1;

[0173] The second end of the tenth capacitor C13 is connected to the current detection voltage input pin CS of the second battery protection chip U1;

[0174] A first end of the eleventh capacitor C14 is connected to a control function pin CNT of the second battery protection chip U1;

[0175] The second end of the eleventh capacitor C14 is connected to the first end of the twelfth capacitor C15;

[0176] A second terminal of the twelfth capacitor C15 is grounded.

[0177] In this embodiment, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube all include: one of a triode and a MOS tube.

[0178] In the temperature protection circuit of the utility model, the output end of the temperature protection chip is connected to the control end of the switch device, so that the switch device is controlled based on the thermistor in a situation where temperature adjustment is required to connect the heating element between the positive and negative electrodes of the battery, thereby providing temperature protection; in addition, the primary protection circuit and the secondary protection circuit are connected in series between the negative electrode and the negative charging terminal of the battery, so that when the control switch fails and the heating element is heated for a long time, the connection between the battery and the charging terminal is disconnected, thereby realizing circuit protection and avoiding battery capacity loss.

[0179] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the utility model in detail. It should be understood that the above description is only a specific embodiment of the utility model and is not intended to limit the protection scope of the utility model. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A battery low temperature protection circuit, characterized in that: include: Primary protection circuit, secondary protection circuit and temperature protection circuit; Wherein, the first end of the primary protection circuit is connected to the negative electrode of the battery; The second end of the primary protection circuit is connected to the first end of the secondary protection circuit; The second terminal of the secondary protection circuit is connected to the negative charging terminal; The temperature protection circuit comprises: a temperature protection chip, a thermistor, a switch device and a heating element; the temperature protection chip comprises: a temperature measurement pin and an output pin; The temperature measuring pin of the temperature protection chip is connected to the first end of the thermistor; The second end of the thermistor is grounded; The output pin of the temperature protection chip is connected to the control end of the switch device; The first end of the switch device is connected to the positive electrode of the battery; The second end of the switch device is connected to the first end of the heating element; The second end of the heating element is connected to the negative electrode of the battery.

2. The battery low temperature protection circuit according to claim 1, characterized in that: The switch device comprises: one of a triode, a MOS tube and a relay device.

3. The battery low temperature protection circuit according to claim 1, characterized in that: The heating element comprises: a first heating wire and a second heating wire; Wherein, the first end of the first heating wire is the first end of the heating element; The second end of the first heating wire is connected to the first end of the second heating wire; The second end of the second heating wire is the second end of the heating element.

4. The battery low temperature protection circuit according to claim 1, characterized in that: The temperature protection circuit also includes a first resistor, a second resistor, a first capacitor and a second capacitor; The first end of the first resistor is connected to the positive electrode of the battery; The second end of the first resistor is connected to the enable input pin of the temperature protection chip; The first end of the second resistor is connected to the positive electrode of the battery; The second end of the second resistor is connected to the battery connection pin of the temperature protection chip and the first end of the first capacitor; The second end of the first capacitor is grounded; The first end of the second capacitor is connected to the battery voltage detection pin of the temperature protection chip; The second terminal of the second capacitor is grounded; Wherein, the enable input pin of the temperature protection chip is connected to the positive electrode of the battery; The battery voltage detection pin of the temperature protection chip is connected to the positive electrode of the battery; The battery connection pin of the temperature protection chip is connected to the positive electrode of the battery; The ground pin of the temperature protection chip is connected to the second end of the thermistor; The ground pin of the temperature protection chip is grounded.

5. The battery low temperature protection circuit according to any one of claims 1 to 4, characterized in that: The primary protection circuit includes: a first battery protection chip, a first switch tube and a second switch tube; wherein the first battery protection chip includes: a discharge protection pin and a charge protection pin The discharge protection pin of the first battery protection chip is connected to the control end of the first switch tube; The first end of the first switch tube is the first end of the primary protection circuit; The second end of the first switch tube is connected to the first end of the second switch tube; The charging protection pin of the first battery protection chip is connected to the control end of the second switch tube; The second end of the second switch tube is the second end of the primary protection circuit.

6. The battery low temperature protection circuit according to claim 5, characterized in that: The first battery protection chip further includes: a current detection voltage input pin, a positive power input pin, a negative power input pin and a test pin; Wherein, the current detection voltage input pin of the first battery protection chip is connected to the negative electrode of the battery; The positive power input pin of the first battery protection chip is connected to the positive electrode of the battery; The negative power input pin of the first battery protection chip is connected to the negative electrode of the battery; The test pin of the first battery protection chip is connected to a preset test point.

7. The battery low temperature protection circuit according to claim 6, characterized in that: The primary protection circuit further includes: a third capacitor, a fourth capacitor, a fifth capacitor, and a sixth capacitor; Wherein, the first end of the third capacitor is connected to the first end of the first switch tube; The second end of the third capacitor is connected to the first end of the fourth capacitor; The second end of the fourth capacitor is connected to the second end of the second switch tube; The first end of the fifth capacitor is connected to the positive power input pin of the first battery protection chip; The second end of the fifth capacitor is connected to the negative power input pin of the first battery protection chip; The first end of the sixth capacitor is connected to the negative power input pin of the first battery protection chip; The second end of the sixth capacitor is connected to the current detection voltage input pin of the first battery protection chip.

8. The battery low temperature protection circuit according to any one of claims 1 to 4, characterized in that: The secondary protection circuit includes: a second battery protection chip, a third switch tube and a fourth switch tube; wherein the second battery protection chip includes: a discharge protection pin and a charge protection pin; The discharge protection pin of the second battery protection chip is connected to the control end of the third switch tube; The first end of the third switch tube is the first end of the secondary protection circuit; The second end of the third switch tube is connected to the first end of the fourth switch tube; The charging protection pin of the second battery protection chip is connected to the control end of the fourth switch tube; The second end of the fourth switch tube is the second end of the secondary protection circuit.

9. The battery low temperature protection circuit according to claim 8, characterized in that: The secondary protection circuit further includes: a sixth resistor, a seventh resistor and an eighth resistor; wherein the second battery protection chip further includes a current detection voltage input pin, a positive power input pin, a negative power input pin, a test pin and a control function pin; The first end of the sixth resistor is connected to the positive electrode of the battery; The second end of the sixth resistor is connected to the positive power input pin of the second battery protection chip; The first end of the seventh resistor is connected to the control function pin of the second battery protection chip; The second end of the seventh resistor is loaded with a preset control signal; A first end of the eighth resistor is connected to a test pin of the second battery protection chip; The second end of the eighth resistor is connected to the negative charging end; The current detection voltage input pin of the second battery protection chip is connected to the negative electrode of the battery; A negative power input pin of the second battery protection chip is grounded.

10. The battery low temperature protection circuit according to claim 9, characterized in that: The secondary protection circuit further includes: a seventh capacitor, an eighth capacitor, a ninth capacitor, a tenth capacitor, an eleventh capacitor and a twelfth capacitor; Wherein, the first end of the seventh capacitor is connected to the first end of the third switch tube; The second end of the seventh capacitor is connected to the first end of the eighth capacitor; The second end of the eighth capacitor is connected to the second end of the fourth switch tube; The first end of the ninth capacitor is connected to the positive power input pin of the second battery protection chip; The second end of the ninth capacitor is connected to the negative power input pin of the second battery protection chip; The first end of the tenth capacitor is connected to the negative power input pin of the second battery protection chip; The second end of the tenth capacitor is connected to the current detection voltage input pin of the second battery protection chip; The first end of the eleventh capacitor is connected to the control function pin of the second battery protection chip; The second end of the eleventh capacitor is connected to the first end of the twelfth capacitor; The second terminal of the twelfth capacitor is grounded.

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