Automobile storage battery power shortage protection circuit and control method thereof

Abstract

The invention discloses an under-voltage protection circuit for an automobile storage battery and a control method of the under-voltage protection circuit. One end of the ignition switch is connected with the storage battery, and the other end is connected with the overload power-off circuit; and the overload power-off circuit is used for preventing the power shortage of the storage battery caused by the excessive power utilization of the load, and comprises a voltage-regulator tube D1, at least two triodes Q1 and Q2, a divider resistor R2 and a divider resistor R3. The protection circuit is low in transformation cost, only a simple circuit needs to be additionally arranged between the storage battery and the vehicle-mounted load, only two triodes and three resistors are needed for cost of the circuit, an additional control module does not need to be added, the protection circuit and the control method detect the automobile storage battery all the time, and the reliability of the automobile storage battery is improved. And the electric quantity of the storage battery can be kept in a reasonable range, so that the problem that the service life of the storage battery is shortened due to overlarge discharge capacity is solved, and the probability that the engine cannot be started due to power shortage of the storage battery is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-mounted intelligent cockpit and vehicle networking, and in particular to a vehicle battery low-power protection circuit and a control method thereof. Background Art

[0002] With the development of automotive electronic technology, there are more and more electronic devices in the car. Although there is no problem of battery power loss when the car is started, if the owner uses the electronic devices in the car when the vehicle is not started, or even turns on the double flash lights for a long time, it is easy to cause the battery voltage to be too low, resulting in ignition failure next time and the vehicle cannot start normally. In the cold winter, the battery's power supply capacity will also be weakened, causing the vehicle to fail to start normally. Because the battery is located in the engine compartment, due to the requirements of the size and weight of the vehicle, it is impossible to solve the problem of power loss by increasing the battery capacity. Summary of the invention

[0003] In view of the above problems, the present invention provides a battery-low protection circuit for an automobile, which prevents the engine from being unable to start due to power shortage caused by excessive power consumption.

[0004] According to one aspect of the present invention, there is provided a vehicle battery low-power protection circuit, comprising: A battery, used to provide electrical energy for the vehicle load; An ignition switch, one end of which is connected to the battery and the other end is connected to the overload power-off circuit; The overload power-off circuit is used to prevent the battery from running out of power due to excessive power consumption by the load, and comprises a voltage-regulating tube D1, at least two transistors Q1 and Q2, a voltage-dividing resistor R2 and a voltage-dividing resistor R3; wherein the negative electrode of the voltage-regulating tube D1 is connected to the base of the transistor Q2, and the positive electrode is connected to the positive electrode of the battery through the voltage-dividing resistors R2 and R3; the base of the transistor Q2 receives the signal of the voltage-regulating tube D1 through the voltage-dividing resistor, the collector is connected to the base of the transistor Q1, and the emitter is grounded; the base of the transistor Q1 is controlled by the transistor Q2, and its collector and emitter are connected to the positive electrode of the battery and the vehicle-mounted load respectively; the voltage-dividing resistor R2 is connected in parallel with the voltage-dividing resistor R3, one end of which is connected to the positive electrode of the voltage-regulating tube D1, and the other end is grounded.

[0005] In an optional manner, the voltage regulator D1 and the voltage-dividing resistor R3 jointly set the over-discharge protection voltage. When the battery voltage drops below the over-discharge protection voltage value, the load power supply is automatically cut off to retain power supply to the ignition function to ensure that the engine can start normally.

[0006] In an optional manner, the circuit also includes a capacitor C1 and a capacitor C2; wherein one end of the capacitor C1 is connected to the voltage-dividing resistor R3, and the other end is connected to the voltage-stabilizing diode D1; one end of the capacitor C2 is connected to the load, and the other end is connected to the voltage-dividing resistor R3.

[0007] In an optional embodiment, the circuit also includes a warning light for indicating whether the circuit is in a protection state, one end of which is connected to the collector of the transistor Q2 or the output end of the logic gate circuit controlled by the state of the transistor Q2, and the other end is grounded or connected to the negative pole of the power supply.

[0008] In an optional manner, an adjustment unit is further included, and the adjustment unit adapts to automobile batteries of different specifications by changing the voltage stabilization value of the voltage regulator tube D1 and the resistance values ​​of the voltage-dividing resistors R2 and R3.

[0009] In an optional manner, it also includes a voltage detection unit, which is connected to the positive electrode of the battery and is used to monitor the battery voltage in real time, and send a control signal to the overload power-off circuit and issue an early warning when the voltage approaches the over-discharge protection threshold.

[0010] In an optional manner, a voltage comparator is also included, one input end of the voltage comparator is connected to the connection point of the voltage-dividing resistors R2 and R3, and the other input end is used to set a reference voltage. When the detected battery voltage is lower than the reference voltage, the transistor Q2 is controlled to be cut off through the output signal of the voltage comparator.

[0011] In an optional manner, it also includes a third capacitor C3 and a control logic circuit, one end of the third capacitor C3 is connected to the positive electrode of the battery, and the other end is connected to the input end of the control logic circuit; wherein the control logic circuit is a comparator, the positive power pin of the comparator is connected to the positive electrode of the battery, and the ground pin is connected to the negative electrode of the battery.

[0012] According to another aspect of the present invention, a control method for a low-power protection circuit of an automobile battery is provided, comprising: Step S1, ignition switch starts the system; Step S2, when the battery voltage is higher than the preset limit value, the voltage is allowed to be supplied to the vehicle load normally; conversely, if the voltage drops below the preset limit voltage, the power supply to the load is immediately cut off to ensure that the battery energy is only used to maintain the power demand of the ignition function.

[0013] In an optional manner, the method further includes: In step S2, the disconnection or connection state of the circuit is indicated by turning on or off the warning light.

[0014] According to the scheme provided by the present invention, it includes: a battery for providing electric energy for a vehicle-mounted load; an ignition switch, one end of which is connected to the battery and the other end is connected to a protection circuit; a protection circuit, which is used to prevent the battery from being depleted due to excessive power consumption of the load, and comprises a voltage-regulating tube D1, at least two transistors Q1 and Q2, a voltage-dividing resistor R2 and a voltage-dividing resistor R3; wherein the negative electrode of the voltage-regulating tube D1 is connected to the base of the transistor Q2, and the positive electrode is connected to the positive electrode of the battery through the voltage-dividing resistors R2 and R3; the base of the transistor Q2 receives a signal from the voltage-regulating tube D1 through the voltage-dividing resistor, the collector is connected to the base of the transistor Q1, and the emitter is grounded; the base of the transistor Q1 is controlled by the transistor Q2, and the collector and emitter thereof are connected to the positive electrode of the battery and the vehicle-mounted load respectively; the voltage-dividing resistor R2 is connected in parallel with the voltage-dividing resistor R3, one end of which is connected to the positive electrode of the voltage-regulating tube D1, and the other end is grounded. The protection circuit provided by the present invention has low modification cost. It only needs to add a simple circuit between the battery and the vehicle-mounted load. The cost of the circuit only needs 2 transistors and 3 resistors. There is no need to add an additional control module. The protection circuit and the control method can be widely used in many cars. The protection circuit and the control method detect the vehicle battery at all times so that the battery power can be maintained in a reasonable range to ensure that the battery life is not shortened due to excessive discharge. The probability of the engine failing to start due to battery power loss is greatly reduced, and the probability of the vehicle failing to start due to excessive power consumption of the electrical circuit when the vehicle is not used for a long time can be reduced.

[0015] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 A schematic diagram of a low-power protection circuit for an automobile battery according to an embodiment of the present invention is shown; Figure 2 A flow chart of a control method for a low-power protection circuit for an automobile battery according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0017] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0018] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0019] Figure 1 The schematic diagram of the automobile battery low-power protection circuit according to the embodiment of the present invention is shown, comprising: A battery, used to provide electrical energy for the vehicle load; An ignition switch, one end of which is connected to the battery and the other end is connected to the protection circuit; A protection circuit is used to prevent the battery from running low due to excessive power consumption by the load, and comprises a voltage regulator D1, at least two transistors Q1 and Q2, a voltage-dividing resistor R2 and a voltage-dividing resistor R3; wherein the negative electrode of the voltage regulator D1 is connected to the base of the transistor Q2, and the positive electrode is connected to the positive electrode of the battery through the voltage-dividing resistors R2 and R3; the base of the transistor Q2 receives the signal of the voltage regulator D1 through the voltage-dividing resistor, the collector is connected to the base of the transistor Q1, and the emitter is grounded; the base of the transistor Q1 is controlled by the transistor Q2, and its collector and emitter are connected to the positive electrode of the battery and the vehicle-mounted load respectively; the voltage-dividing resistor R2 is connected in parallel with the voltage-dividing resistor R3, one end of which is connected to the positive electrode of the voltage regulator D1, and the other end is grounded.

[0020] The working principle of the protection circuit provided in this embodiment is as follows: after the switch S1 is closed, since the battery is initially fully charged, the voltage of the battery causes the voltage regulator D1 to conduct in the reverse direction, so that the base of the transistor Q2 has a bias voltage, and Q2 is saturated and turned on. When Q2 is turned on, the base of Q1 will also have a corresponding current flowing through it, and Q1 will also be saturated and turned on. In this way, the battery supplies power to the load through the switch tube Q1. In the circuit, Q1 is used as a switch tube, and the current flowing through it will be larger. In actual production, try to select a transistor with slightly larger power.

[0021] As the battery slowly discharges, the battery voltage begins to decrease. When it drops to a level that is not enough to reverse the conduction of D1 (below the over-discharge protection voltage), Q2 is turned off, and Q1 is also turned off. In this way, the turn-off of the switch tube Q1 cuts off the circuit between the battery and the load, protecting the battery. By adjusting the voltage value of the voltage regulator tube and the resistance values ​​of the voltage divider resistors R2 and R3, you can try batteries with different voltages.

[0022] The advantage of this embodiment is that the modification cost of the protection circuit is relatively low. Only a simple circuit needs to be added between the battery and the vehicle load. The cost of the circuit only requires 2 transistors and 3 resistors. No additional control module needs to be added. It can be widely used in many cars. The protection circuit and control method always detect the car battery so that the battery power can be maintained within a reasonable range to ensure that the battery life is not shortened due to excessive discharge. The probability of the engine failing to start due to battery depletion is greatly reduced, and the probability of the vehicle failing to start due to excessive power consumption of the electrical circuit when the vehicle is not used for a long time can be reduced.

[0023] In an optional manner, the voltage regulator D1 and the voltage-dividing resistor R3 jointly set the over-discharge protection voltage. When the battery voltage drops below the over-discharge protection voltage value, the load power supply is automatically cut off to retain power supply to the ignition function to ensure that the engine can start normally.

[0024] In this embodiment, the voltage regulator D1 acts as a voltage reference. The voltage regulator starts to conduct only when the voltage across it exceeds its stable voltage. Therefore, the stable voltage of the voltage regulator D1 plus the voltage drop on the voltage-dividing resistor R3 jointly determine the over-discharge protection threshold of the circuit. The voltage-dividing resistor R3 connected in series with the voltage regulator D1 works together with R2 to adjust the voltage reaching the base of the transistor Q2 through the principle of resistor voltage division. When the battery voltage drops to a certain level, the voltage drop through R3 decreases, so that the voltage applied to the base of Q2 is lower than its conduction threshold, thereby controlling the action of the subsequent circuit. When the battery voltage gradually decreases due to discharge and reaches the over-discharge protection voltage set by the voltage regulator D1 and R3, the voltage regulator D1 is no longer turned on or its conduction degree is weakened, resulting in a decrease in the bias voltage of the base of the transistor Q2, and the transistor Q2 is cut off. The cut-off of the transistor Q2 causes the transistor Q1 to lose its bias current, and it is also cut off, thereby cutting off the power supply from the battery to the vehicle load. Therefore, although the load is no longer powered, it can be ensured that at least enough power is left to supply the ignition system to ensure normal starting of the engine.

[0025] In an optional manner, the circuit also includes a capacitor C1 and a capacitor C2; wherein one end of the capacitor C1 is connected to the voltage-dividing resistor R3, and the other end is connected to the voltage-stabilizing diode D1; one end of the capacitor C2 is connected to the load, and the other end is connected to the voltage-dividing resistor R3.

[0026] In this embodiment, when the load is suddenly disconnected or the power supply is briefly interrupted, the capacitor C2 can release the previously stored energy to provide short-term power support for the load, thereby avoiding circuit malfunction or restart caused by instantaneous voltage drop.

[0027] In an optional embodiment, the circuit also includes a warning light for indicating whether the circuit is in a protection state, one end of which is connected to the collector of the transistor Q2 or the output end of the logic gate circuit controlled by the state of the transistor Q2, and the other end is grounded or connected to the negative pole of the power supply.

[0028] In this embodiment, under normal circumstances, that is, the battery voltage is sufficient, the transistor Q2 is turned on, and the circuit allows current to flow to the vehicle load. The warning light is not on, indicating that the circuit is not in a protection state. Once the battery voltage drops below the set protection level, the transistor Q2 is turned off, and the circuit cuts off the power supply to the load. At this time, the current path flowing through the warning light is established, and the warning light is on, prompting the driver or maintenance personnel that the circuit is in a protection state, that is, the battery is being protected to prevent excessive discharge.

[0029] In an optional manner, an adjustment unit is further included, and the adjustment unit adapts to automobile batteries of different specifications by changing the voltage stabilization value of the voltage regulator tube D1 and the resistance values ​​of the voltage-dividing resistors R2 and R3.

[0030] In this embodiment, the adjustment unit fine-tunes the protection circuit according to different types and capacities of automobile batteries. Specifically, the adjustment unit sets the trigger point of over-discharge protection by replacing voltage regulator tubes with different voltage stabilization values, and finds the most suitable protection voltage threshold through adjustment. The adjustment unit fine-tunes the voltage divider ratio by replacing resistors with different resistance values ​​or using variable resistors to adapt to the requirements for the sensitivity of the protection circuit under different voltage levels. Even if the vehicle is under extreme temperature conditions (such as battery performance degradation caused by severe cold), the response of the protection circuit can be ensured by adjusting the resistance value of the voltage divider resistor.

[0031] In an optional manner, it also includes a voltage detection unit, which is connected to the positive electrode of the battery and is used to monitor the battery voltage in real time, and send a control signal to the protection circuit and issue an early warning when the voltage approaches an over-discharge protection threshold.

[0032] In this embodiment, the voltage detection unit continuously monitors the voltage level of the battery to achieve continuous and real-time voltage sampling. When the detected voltage value approaches but has not reached the over-discharge protection threshold, the comparator output changes and generates a warning signal. The warning signal is sent to the protection circuit to notify the driver or vehicle management system that the battery power is about to reach a critical point and measures need to be taken, such as reducing the use of non-essential electronic devices or starting the vehicle as soon as possible for charging.

[0033] In an optional manner, a voltage comparator is also included, one input end of the voltage comparator is connected to the connection point of the voltage-dividing resistors R2 and R3, and the other input end is used to set a reference voltage. When the detected battery voltage is lower than the reference voltage, the transistor Q2 is controlled to be cut off through the output signal of the voltage comparator.

[0034] In this embodiment, when the battery voltage is higher than the set reference voltage, the output of the voltage comparator is low, so that the transistor Q2 remains in the on state, thereby allowing the transistor Q1 to also be turned on, so that the battery can normally supply power to the vehicle load. Once the detected battery voltage drops due to discharge and reaches or falls below the preset reference voltage, the output of the voltage comparator switches to a high level. This causes the base of the transistor Q2 to lose the bias voltage and thus be cut off. The cut-off of the transistor Q2 immediately causes the transistor Q1 to enter the cut-off state, effectively cutting off the power supply circuit between the battery and the vehicle load, and avoiding deep power loss of the battery due to continued power consumption of the load.

[0035] In an optional manner, it also includes a third capacitor C3 and a control logic circuit, one end of the third capacitor C3 is connected to the positive electrode of the battery, and the other end is connected to the input end of the control logic circuit; wherein the control logic circuit is a comparator, the positive power pin of the comparator is connected to the positive electrode of the battery, and the ground pin is connected to the negative electrode of the battery.

[0036] In this embodiment, one end of the third capacitor C3 is directly connected to the positive electrode of the battery, and the other end is connected to the input end of the control logic circuit (not shown in the figure). When the vehicle starts, the third capacitor C3 starts to charge. Since it takes a certain amount of time for the capacitor to charge, this charging process can be used as a natural delay mechanism. Before the capacitor is fully charged, the control logic circuit does not issue an instruction to turn on the transistor Q1, thereby temporarily preventing the current from flowing to the vehicle load. The third capacitor C3 can also smooth the current impact at the moment of startup to a certain extent, avoid excessive pressure on the battery and circuit, and is conducive to protecting the long-term health of the battery and circuit components. The control logic circuit receives the charging dynamic information from C3, and decides when to let the protection circuit release the restriction on the load power supply based on the preset delay time or voltage threshold. When C3 is charged to a predetermined level, that is, when the set delay time or voltage threshold is reached, the control logic circuit outputs a signal to turn on the transistor Q1, thereby allowing current to flow to the vehicle load. The control logic circuit can be a simple comparator or logic gate circuit. When the control logic circuit is a comparator (not shown in the figure), the positive power supply pin of the comparator is connected to the positive electrode of the battery through a voltage regulator diode (not shown in the figure) to ensure that the comparator obtains a stable operating voltage, and the ground pin is directly connected to the negative electrode of the battery.

[0037] Figure 2 A flow chart showing a control method of a low-power protection circuit for an automobile battery according to an embodiment of the present invention is provided, comprising the following steps: Step S1, ignition switch starts the system; Step S2, when the battery voltage is higher than the preset limit value, the voltage is allowed to be supplied to the vehicle load normally; conversely, if the voltage drops below the preset limit voltage, the power supply to the load is immediately cut off to ensure that the battery energy is only used to maintain the power demand of the ignition function.

[0038] For example, when the driver operates the ignition switch, the circuit system begins to activate. The ignition switch is the main switch of the circuit. After closing, it establishes a current path from the car battery to the entire circuit system. If the detected battery voltage is higher than the preset safety lower limit, it indicates that the battery is sufficient to meet the normal operation of the on-board electronic equipment. The circuit remains unobstructed, allowing the battery's power to be smoothly transmitted to various on-board loads, such as lights, audio, and infotainment systems, to ensure that all functions of the vehicle can be powered during driving. The battery voltage drops below the preset low voltage threshold, usually due to reasons such as not starting the vehicle for a long time, excessive use of on-board equipment, or battery aging. At this time, the protection mechanism is immediately activated, quickly cutting off the power supply to non-critical on-board loads, ensuring that the vehicle's entertainment system and other non-essential equipment lose power supply, but the most critical ignition system can still obtain enough power to ensure that the engine can be successfully started. The purpose is to prioritize the battery's power for ignition and avoid the dilemma of being unable to start the vehicle due to excessive battery discharge. This protection circuit effectively balances the use requirements of on-board electronic equipment and the relationship between ensuring the vehicle's starting ability. It not only meets the convenience of daily driving, but also ensures that the vehicle can be started smoothly in an emergency, greatly improving the reliability of automobile use and user experience.

[0039] In an optional manner, the method further includes: In step S2, the disconnection or connection state of the circuit is indicated by turning on or off the warning light.

[0040] For example, when the voltage of the car battery is higher than the preset limit voltage, the circuit maintains normal working state, that is, the battery is allowed to supply power to the on-board load. At this time, the warning light is off and the protection mechanism is not activated. Once it is detected that the battery voltage drops below the preset limit voltage, the protection mechanism in the circuit will respond immediately and automatically cut off the power supply to the on-board load to ensure that the remaining power is mainly used for the ignition function to prevent the engine from failing to start due to power loss. The warning light is lit to prompt the driver or vehicle maintenance personnel that the circuit has entered the protection mode and some or all non-critical electronic equipment is restricted from use due to insufficient power.

[0041] According to the scheme provided by the present invention, it includes: a battery for providing electric energy for a vehicle-mounted load; an ignition switch, one end of which is connected to the battery and the other end is connected to a protection circuit; a protection circuit, which is used to prevent the battery from being depleted due to excessive power consumption of the load, and comprises a voltage-regulating tube D1, at least two transistors Q1 and Q2, a voltage-dividing resistor R2 and a voltage-dividing resistor R3; wherein the negative electrode of the voltage-regulating tube D1 is connected to the base of the transistor Q2, and the positive electrode is connected to the positive electrode of the battery through the voltage-dividing resistors R2 and R3; the base of the transistor Q2 receives a signal from the voltage-regulating tube D1 through the voltage-dividing resistor, the collector is connected to the base of the transistor Q1, and the emitter is grounded; the base of the transistor Q1 is controlled by the transistor Q2, and the collector and emitter thereof are connected to the positive electrode of the battery and the vehicle-mounted load respectively; the voltage-dividing resistor R2 is connected in parallel with the voltage-dividing resistor R3, one end of which is connected to the positive electrode of the voltage-regulating tube D1, and the other end is grounded. The protection circuit provided by the present invention has low modification cost. It only needs to add a simple circuit between the battery and the vehicle-mounted load. The cost of the circuit only needs 2 transistors and 3 resistors. There is no need to add an additional control module. The protection circuit and the control method can be widely used in many cars. The protection circuit and the control method detect the vehicle battery at all times so that the battery power can be maintained in a reasonable range to ensure that the battery life is not shortened due to excessive discharge. The probability of the engine failing to start due to battery power loss is greatly reduced, and the probability of the vehicle failing to start due to excessive power consumption of the electrical circuit when the vehicle is not used for a long time can be reduced.

[0042] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

[0043] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0044] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0045] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0046] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A car battery low power protection circuit, characterized in that: include: A battery, used to provide electrical energy for the vehicle load; An ignition switch, one end of which is connected to the battery and the other end is connected to the overload power-off circuit; The overload power-off circuit is used to prevent the battery from running out of power due to excessive power consumption by the load, and comprises a voltage-regulating tube D1, at least two transistors Q1 and Q2, a voltage-dividing resistor R2 and a voltage-dividing resistor R3; wherein the negative electrode of the voltage-regulating tube D1 is connected to the base of the transistor Q2, and the positive electrode is connected to the positive electrode of the battery through the voltage-dividing resistors R2 and R3; the base of the transistor Q2 receives the signal of the voltage-regulating tube D1 through the voltage-dividing resistor R2, the collector is connected to the base of the transistor Q1, and the emitter is grounded; the base of the transistor Q1 is controlled by the transistor Q2, and its collector and emitter are connected to the positive electrode of the battery and the vehicle-mounted load respectively; the voltage-dividing resistor R2 is connected in parallel with the voltage-dividing resistor R3, one end of which is connected to the positive electrode of the voltage-regulating tube D1, and the other end is grounded.

2. The automobile battery low power protection circuit according to claim 1, characterized in that: The voltage regulator D1 and the voltage-dividing resistor R3 jointly set the over-discharge protection voltage. When the battery voltage drops below the over-discharge protection voltage value, the load power supply is automatically cut off to retain the power supply to the ignition function to ensure that the engine can start normally.

3. The automobile battery low power protection circuit according to claim 1 or 2, characterized in that: The circuit also includes a capacitor C1 and a capacitor C2; wherein one end of the capacitor C1 is connected to the voltage-dividing resistor R3, and the other end is connected to the voltage-stabilizing diode D1; one end of the capacitor C2 is connected to the load, and the other end is connected to the voltage-dividing resistor R3.

4. The automobile battery low power protection circuit according to claim 1, characterized in that: The circuit also includes a warning light for indicating whether the circuit is in a protection state, one end of which is connected to the collector of transistor Q2 or the output end of a logic gate circuit controlled by the state of transistor Q2, and the other end is grounded or connected to the negative pole of a power supply.

5. The automobile battery low power protection circuit according to claim 1, characterized in that: The invention also comprises an adjusting unit, which adapts to automobile batteries of different specifications by changing the voltage stabilizing value of the voltage stabilizing tube D1 and the resistance values ​​of the voltage dividing resistors R2 and R3.

6. The automobile battery low power protection circuit according to claim 1, characterized in that: It also includes a voltage detection unit, which is connected to the positive electrode of the battery and is used to monitor the battery voltage in real time, and send a control signal to the overload power-off circuit and issue an early warning when the voltage approaches the over-discharge protection threshold.

7. The automobile battery low power protection circuit according to claim 1, characterized in that: It also includes a voltage comparator, one input end of which is connected to the connection point of the voltage-dividing resistors R2 and R3, and the other input end is used to set a reference voltage. When the detected battery voltage is lower than the reference voltage, the transistor Q2 is controlled to be cut off through the output signal of the voltage comparator.

8. The automobile battery low power protection circuit according to claim 1, characterized in that: It also includes a third capacitor C3 and a control logic circuit, one end of the third capacitor C3 is connected to the positive electrode of the battery, and the other end is connected to the input end of the control logic circuit; wherein the control logic circuit is a comparator, the positive power pin of the comparator is connected to the positive electrode of the battery, and the ground pin is connected to the negative electrode of the battery.

9. A control method for a low-power protection circuit of an automobile battery, characterized in that: include: Step S1, ignition switch starts the system; Step S2, when the battery voltage is higher than the preset limit value, the voltage is allowed to be supplied to the vehicle load normally; conversely, if the voltage drops below the preset limit voltage, the power supply to the load is immediately cut off to ensure that the battery energy is only used to maintain the power demand of the ignition function.

10. The control method according to claim 9, characterized in that: The method further comprises: In step S2, the disconnection or connection state of the circuit is indicated by turning on or off the warning light.

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