A vehicle-mounted lead-acid battery charging apparatus and method

Abstract

The application discloses a kind of vehicle-mounted lead-acid battery charging equipment and method, the equipment is mainly by input protection module, voltage stabilizing module, output protection module and control and display module constitute;Among them, input protection module provides overcurrent protection to alternating current input, provides polarity error protection to direct current input;Voltage stabilizing module rectifies for alternating current input, and voltage stabilizing is carried out for direct current input and rectified alternating current input;Output protection module provides current limiting, voltage limiting and polarity error protection for load access;Control and display module provide 12V and 24V switching of direct current output voltage, and protection action prompting function.The charging equipment and method, on the basis that input source can be 220V alternating current mains, increase 24V direct current input, broaden the equipment use scene;Increase direct current access error protection in front and rear stage, improve charging operation safety, provide limited current charging for vehicle-mounted battery power supply condition.

Description

Technical Field

[0001] This invention relates to a battery charging device and method, and more particularly to a vehicle-mounted lead-acid battery charging device and method. Background Technology

[0002] Most automobiles are equipped with DC lead-acid batteries, and some vehicles even have lead-acid batteries in multiple locations due to functional requirements. During daily use, if the battery is over-discharged, it needs to be recharged. However, most chargers on the market (such as the lead-acid battery charger described in CN201720356955X) use AC input for charging. This charging method, in the specific and common environment of over-discharge of vehicle lead-acid batteries, not only limits the power supply for charging but may also damage the charger and battery if the DC output polarity is reversed, affecting the lifespan of both. Therefore, improvements to battery charging in this situation are needed. Summary of the Invention

[0003] Purpose of the invention: The technical problem to be solved by the present invention is to provide a vehicle-mounted lead-acid battery charging device and method to address the shortcomings of the prior art.

[0004] To address the aforementioned technical problems, this invention discloses an on-board lead-acid battery charging device, comprising: an input protection module, a voltage regulator module, an output protection module, and a control and display module;

[0005] The system includes an input protection module for protecting against both AC and DC inputs; a voltage regulator module for rectifying the AC input and regulating the voltage of both the DC input and the rectified AC input; an output protection module for protecting against incorrect connection of the load battery and for current limiting; and a control and display module for displaying the connection status of the input power supply and load battery based on the device's input and output selections, and for controlling the input, output, and protection limits of the input protection module, voltage regulator module, and output protection module.

[0006] The input protection module includes an AC input protection circuit and a DC input protection circuit; the input mode is controlled by the control and display module, and the AC input protection circuit and DC input protection circuit are used according to the input mode.

[0007] The AC input protection circuit described above provides overcurrent protection using a fuse, and specifically includes: an input selection switch, a second capacitor, a fourth resistor, a fuse, and an AC relay;

[0008] One end of the input selection switch is connected to one end of the AC input, the other end of the input selection switch is connected to the second capacitor, the other end of the second capacitor is connected to one end of the fuse, the other end of the fuse is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to one end of the transformer in the voltage stabilizing module as an output end of the AC input protection circuit.

[0009] The DC input protection circuit uses the switching characteristic of the PMOS tube for reverse connection protection, and specifically comprises an input selection switch, a first capacitor, a first zener diode, a first PMOS tube, a first resistor, a second resistor, a third resistor, and a coil of a first DC relay.

[0010] One end of the input selection switch is connected to the positive pole of the input DC power supply, the other end of the input selection switch is connected to the S end of the first PMOS tube, one end of the first capacitor, and one end of the first zener diode, the other end of the first capacitor and the first zener diode is connected to one end of the first resistor and the second resistor, the other end of the first resistor is connected to the G end of the first PMOS tube, the other end of the second resistor is connected to the negative pole of the input DC power supply and one end of the coil of the first DC relay, and is connected to the voltage stabilizing circuit in the voltage stabilizing module, the other end of the coil of the first DC relay is connected to one end of the third resistor, the D end of the first PMOS tube is connected to the other end of the third resistor and is connected to the voltage stabilizing circuit in the voltage stabilizing module.

[0011] The output protection module comprises a current limiting circuit, a load access protection module, and a charging monitoring module.

[0012] The load polarity protection module uses the switching characteristic of the PMOS tube for reverse connection protection, and comprises a third capacitor, a second zener diode, a second PMOS tube, an eleventh resistor, a twelfth resistor, a thirteenth resistor, and a fourth DC relay.

[0013] One end of the third capacitor and the second zener diode is connected to the positive pole of the load battery and the S end of the second PMOS tube, the other end of the third capacitor and the second zener diode is connected to one end of the eleventh resistor and the twelfth resistor, the other end of the eleventh resistor is connected to the G end of the second PMOS tube, the other end of the twelfth resistor is connected to the negative pole of the load battery and one end of the coil of the fourth DC relay, and is connected to one port of the charging monitoring module, the other end of the coil of the fourth DC relay is connected to one end of the thirteenth resistor, the other end of the thirteenth resistor is connected to the D end of the second PMOS tube, and is connected to the other port of the charging monitoring module and one port of the load voltage level protection module.

[0014] The load voltage level protection module uses an operational amplifier to determine the voltage level of the input circuit, and comprises a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a first operational amplifier, a second operational amplifier, a third diode, a fourth diode, and a third DC relay;

[0015] The one end of the fourteenth resistor is connected with one port of the load polarity protection module and the charging monitoring module, the one end of the seventeenth resistor is connected with an input power supply, the other end is connected with the positive electrode of the second operational amplifier, and is connected with the one end of the eighteenth resistor, the other end of the eighteenth resistor is grounded, the other end of the fourteenth resistor is connected with the negative electrode of the first operational amplifier and the second operational amplifier, the one end of the fifteenth resistor is connected with the input power supply, the other end is connected with the negative electrode of the first operational amplifier, and is connected with the one end of the sixteenth resistor, the other end of the sixteenth resistor is grounded, the output ends of the first operational amplifier and the second operational amplifier are respectively connected with the one end of the nineteenth resistor through the third diode and the fourth diode, the other end of the nineteenth resistor is connected with the one end of the coil of the third DC relay, and the other end of the coil of the third DC relay is connected with the charging monitoring module and the one end of the current limiting circuit.

[0016] The charging monitoring module uses the switching characteristics of a triode to perform overcharge protection, and comprises a twenty-first resistor, a twentieth resistor, an LED indicator, and a third triode and a third DC relay.

[0017] The one end of the twentieth resistor is connected with the load polarity protection module and the one end of the current limiting circuit, the other end of the twentieth resistor is connected with the one end of the LED indicator, the other end of the LED indicator is connected with the E electrode of the third triode, the C electrode of the third triode is connected with the one end of the twenty-first resistor, and is connected with the one end of the load voltage level protection module and the other end of the load polarity protection module, the B electrode of the third triode is connected with the other end of the twenty-first resistor, and is connected with the one end of the normally closed contact of the third DC relay, and the other end of the normally closed contact of the third DC relay is connected with the other end of the load voltage level protection module.

[0018] The control and display module judges the setting and the access result of the front-stage input type and the rear-stage load type of the charging device, if the setting and the access result are consistent, the charging device performs a charging strategy, otherwise, the charging device does not start charging.

[0019] The application further provides a vehicle-mounted lead-acid battery charging method, and the vehicle-mounted lead-acid battery charging device is used to perform charging, and the method comprises the following steps:

[0020] Step 1, setting an input type; the input type comprises a direct current input and an alternating current input.

[0021] Step 2, according to the input type, access the input current, and make input judgment; when the input access is normal, light the input indicator, otherwise the input indicator is not lighted;

[0022] Step 3, set the output type; the output type includes: direct current 12 volt output DC12V and direct current 24 volt output DC24V;

[0023] Step 4, according to the output type, access the output load, and judge the load battery polarity and load voltage; when the load battery polarity is correct, light the output polarity indicator, otherwise the output polarity indicator is not lighted; when the load voltage is in the allowed range of the set output voltage, light the output voltage indicator, and enter step 5; otherwise the output voltage indicator is not lighted;

[0024] Step 5, when the judgment in step 4 is correct, the input indicator, the output polarity indicator and the output voltage indicator are all lighted, and the device is ready;

[0025] Step 6, open the working switch, and output according to the set mode;

[0026] Step 7, judge the load voltage, if the charging is not completed, continue to charge, otherwise light the charging completion indicator, and complete the charging.

[0027] Beneficial effects:

[0028] The application provides a kind of vehicle-mounted lead-acid battery charging equipment and method, it has polarity reverse connection protection and detection, commonly used alternating current mains or wide DC input, DC 24V / 12V output switching, load current output control and other advantages, provides multiple charging and protection means for over-discharged lead-acid battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] The above and / or other aspects of the present application will become apparent by referring to the following description taking in conjunction with the accompanying drawings, wherein:

[0030] Figure 1 It is the schematic diagram of the overall structure of the application.

[0031] Figure 2 It is the connection schematic diagram of the input protection module and the voltage stabilizing module of the charging equipment.

[0032] Figure 3 It is the connection schematic diagram of the output protection module and the voltage stabilizing module of the charging equipment.

[0033] Figure 4 It is the display schematic diagram of the control and display module of the charging equipment.

[0034] Figure 5is a process flow diagram of the charging device performing charging. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be further described in detail below with reference to the accompanying drawings:

[0036] A vehicle-mounted lead-acid battery charging device, as shown in the figure, comprises an input protection module, a voltage stabilization module, an output protection module, and a control and display module. Figure 1

[0037] The input protection module realizes access protection of AC input and DC input; the voltage stabilization module rectifies AC input and stabilizes DC input and rectified AC input; the output protection module protects and limits current output of the load battery; and the control and display module displays the access of input power supply and load battery according to the input and output selection of the device, and controls the input, output and protection limitation of the input protection module, voltage stabilization module and output protection module.

[0038] As shown in the figure, the input protection module comprises an AC input protection circuit and a DC input protection circuit; the input mode is controlled through the control and display module, and the AC input protection circuit and the DC input protection circuit are used according to the input mode. Figure 2 The AC input protection circuit uses a fuse to provide overcurrent protection, and specifically comprises an input selection switch S1, a second capacitor C2, a fourth resistor R4, a fuse F1 and a coil of an AC relay K2.

[0039] One end of the input selection switch S1 is connected to one end of the AC input, the other end of the input selection switch S1 is connected to the second capacitor C2, the other end of the second capacitor C2 is connected to one end of the fuse F1, the other end of the fuse F1 is connected to one end of the fourth resistor R4, and the fourth resistor R4 is connected to the coil of the AC relay K2, and the other end of the coil of the AC relay K2 is connected to the other end of the input AC power supply and the other end of the transformer in the voltage stabilization module.

[0040] The DC input protection circuit uses the switching characteristic of a PMOS tube to provide reverse connection protection, and specifically comprises an input selection switch S1, a first capacitor C1, a first voltage stabilization diode D1, a first PMOS tube Q1, a first resistor R1, a second resistor R2, a third resistor R3 and a coil of a first DC relay K1.

[0041]

[0042] ​​The one end of the input selection switch S1 is connected with the positive pole of the input DC power supply, the other end of the input selection switch S1 is connected with the S end of the first PMOS tube Q1, the one end of the first capacitor C1 and the one end of the first voltage stabilizing diode D1, the other end of the first capacitor C1 and the other end of the first voltage stabilizing diode D1 are connected with the one end of the first resistor R1 and the one end of the second resistor R2, the other end of the first resistor R1 is connected with the G end of the first PMOS tube Q1, the other end of the second resistor R2 is connected with the negative pole of the input DC power supply and the one end of the coil of the first DC relay K1, and is connected with the voltage stabilizing circuit in the voltage stabilizing module, the other end of the coil of the first DC relay K1 is connected with the one end of the third resistor R3, and the D end of the first PMOS tube Q1 is connected with the other end of the third resistor R3 and is connected with the voltage stabilizing circuit in the voltage stabilizing module.

[0043] As shown in Figure 3 The output protection module comprises a current limiting circuit, a load access protection module and a charging monitoring module, wherein the load access protection module comprises a load polarity protection module and a load voltage level protection module.

[0044] The load polarity protection module uses the switching characteristics of the PMOS tube for reverse connection protection, and comprises a third capacitor C3, a second voltage stabilizing diode D2, a second PMOS tube Q2, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13 and the coil of a fourth DC relay K4.

[0045] The positive pole of the load battery is connected with the one end of the third capacitor C3 and the one end of the second voltage stabilizing diode D2, and is connected with the S end of the second PMOS tube Q2, the other end of the third capacitor C3 and the other end of the second voltage stabilizing diode D2 are connected with the one end of the eleventh resistor R11 and the one end of the twelfth resistor R12, the other end of the eleventh resistor R11 is connected with the G end of the second PMOS tube Q2, the other end of the twelfth resistor R12 is connected with the negative pole of the load battery and the one end of the coil of the fourth DC relay K4, and is connected with one port of the charging monitoring module, the other end of the coil of the fourth DC relay K4 is connected with the one end of the thirteenth resistor R13, and the other end of the thirteenth resistor R13 is connected with the D end of the second PMOS tube Q2, and is connected with the other port of the charging monitoring module and one port of the load voltage level protection module.

[0046] The load voltage level protection module uses the operational amplifier to determine the voltage level of the access circuit, and comprises a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a first operational amplifier U1A, a second operational amplifier U1B, a third diode D3, a fourth diode D4 and the coil of a third DC relay K3.

[0047] One end of the fourteenth resistor R14 is connected with one port of the load polarity protection module and the charging monitoring module, one end of the seventeenth resistor R17 is connected with the input power Vo, the other end is connected with the positive electrode of the second operational amplifier U1B, and is connected with one end of the eighteenth resistor R18, the other end of the eighteenth resistor R18 is grounded, the other end of the fourteenth resistor R14 is connected with the negative electrode of the first operational amplifier U1A and the second operational amplifier U1B, one end of the fifteenth resistor R15 is connected with the input power Vo, the other end is connected with the negative electrode of the first operational amplifier U1A, and is connected with one end of the sixteenth resistor R16, the other end of the sixteenth resistor R16 is grounded, the output ends of the first operational amplifier U1A and the second operational amplifier U1B are respectively connected with one end of the nineteenth resistor R19 through the third diode D3 and the fourth diode D4, the other end of the nineteenth resistor R19 is connected with one end of the coil of the third direct current relay K3, the other end of the coil of the third direct current relay K3 is connected with the charging monitoring module, and is connected with one end of the current limiting circuit.

[0048] The charging monitoring module uses the switching characteristic of the triode to perform overcharge protection, and comprises the twenty-first resistor R21, the twentieth resistor R20, the LED indicator lamp LED4, the third triode Q3 and the normally closed contact of the third direct current relay K3.

[0049] One end of the twentieth resistor R20 is connected with one end of the load polarity protection module and the current limiting circuit, the other end of the twentieth resistor R20 is connected with one end of the LED indicator lamp LED4, the other end of the LED indicator lamp LED4 is connected with the E electrode of the third triode Q3, one end of the twenty-first resistor R21 is connected with the C electrode of the third triode Q3, and is connected with one end of the load voltage level protection module and the other end of the load polarity protection module, the other end of the twenty-first resistor R21 is connected with the B electrode of the third triode Q3, and is connected with one end of the normally closed contact of the third direct current relay K3, the other end of the normally closed contact of the third direct current relay K3 is connected with the other end of the load voltage level protection module.

[0050] As shown in Figure 4 The control and display module judges the setting and access result of the front-stage input type and the rear-stage load type of the charging device, if the setting and the access result are consistent, the charging device performs the charging strategy, otherwise, the charging is not started.

[0051] A vehicle-mounted lead-acid battery charging method, using the vehicle-mounted lead-acid battery charging device to charge, as shown in Figure 5 The method comprises the following steps:

[0052] Step 1, setting the input type; the input type comprises: direct current input and alternating current input;

[0053] Step 2, according to the input type, access the input current, and make input judgment; when the input access is normal, light up the input indicator, otherwise the input indicator is not lit;

[0054] Step 3, set the output type; the output type includes: direct current 12 volt output DC12V and direct current 24 volt output DC24V;

[0055] Step 4, according to the output type, access the output load, and judge the load battery polarity and load voltage; when the load battery polarity is correct, light up the output polarity indicator, otherwise the output polarity indicator is not lit; when the load voltage is in the allowed range of the set output voltage, light up the output voltage indicator, and enter step 5; otherwise the output voltage indicator is not lit;

[0056] Step 5, when the judgments in step 4 are all correct, the input indicator, the output polarity indicator and the output voltage indicator are all lit, and the device is ready;

[0057] Step 6, turn on the working switch, and output according to the set mode;

[0058] Step 7, judge the load voltage, if the charging is not completed, continue to charge, otherwise light up the charging completion indicator and complete the charging.

[0059] Embodiment 1:

[0060] A vehicle-mounted lead-acid battery charging device, as shown in Figure 1 , is designed into four modules:

[0061] Module 1: input protection module;

[0062] Module 2: voltage stabilizing module;

[0063] Module 3: output protection module;

[0064] Module 4: control and display module.

[0065] The AC input protection module in the module 1, i.e. the input protection module, specifically includes:

[0066] AC input terminal, linkage input selection switch, capacitor, AC fuse, power resistor and AC relay. The AC input terminal is used to access AC power; the linkage input selection switch is connected in series after the AC input terminal, and is opened and closed according to the device input selection; the AC fuse is connected in series after the selection switch, and provides overcurrent protection. The AC relay is switched after the device accesses the AC power, and is associated with the control and display module.

[0067] The DC input protection module in the module 1, i.e. the input protection module, specifically includes:

[0068] The direct current input terminal, linkage input selection switch, PMOS tube (P-channel silicon MOS field effect transistor), voltage stabilizing tube, resistance, capacitor and direct current relay are connected. Figure 2

[0069] The module 2, i.e. the voltage stabilizing module, specifically comprises a transformer, rectifier and voltage stabilizing circuit.

[0070] The module 3, i.e. the output protection module, specifically comprises a current limiting output module, direct current input protection module and charging monitoring circuit. 15 18 The resistance R The charging monitoring circuit utilizes the triode Q3 to have a certain emission junction positive bias voltage, and when the battery charging current is small, the LED indicator D3 is lighted, and the charging is stopped. Figure 3

[0071] The module 4, i.e. the control and display module, is composed of a relay action switch and indicator lamp, as shown in the figure. Figure 4 When the input selected by the input selection switch is consistent with the input power connected, and the output selected by the output selection switch is consistent with the battery voltage level connected, all the indicator lamps are lighted, and the device starts to work.

[0072] The application further provides a vehicle-mounted lead-acid battery charging method, which uses the vehicle-mounted lead-acid battery charging device. Figure 5

[0073] Step 1: setting input type; the input type comprises direct current input and alternating current input;

[0074] ​​​​Step 2, according to the input type, access the input current, and make input judgment;

[0075] Step 3, set the output type; the output type includes: DC12V and DC24V;

[0076] Step 4, according to the output type, judge the load battery polarity and load voltage;

[0077] Step 5, when the judgment is correct, the device is ready;

[0078] Step 6, open the working switch, and start output according to the set mode;

[0079] Step 7, judge the load voltage, and complete charging.

[0080] Example 2, combined Figure 2 , Figure 3 , the device performs charging of AC 220V to DC 24V device, and the process is executed in the order of steps 1, 2, and 3:

[0081] 1. After the device sets the charging input to 220V AC and the output to 24V DC, wait for AC input access, and DC access is invalid.

[0082] 2. The AC input is normally connected, converted into low voltage by the transformer, rectified into DC by the rectifier, and then output stable DC voltage by the voltage stabilizer; the AC relay K2 is energized, the K2 normally open contact is closed, and the input indicator light is lit.

[0083] 3. After the load battery is normally connected, the parasitic diode of MOS tube Q2 is turned on, the DC relay K4 is energized, the normally open contact of K4 is closed, and the output polarity indicator light is lit.

[0084] 4. When the load voltage is not greater than and not less than , the operational amplifier outputs high level, the DC relay K3 does not act, and the output voltage indicator light is lit.

[0085] 5. After the parasitic diode is turned on, the gate-source voltage of the MOS tube is positively biased, the MOS tube is turned on, and the device starts to work.

[0086] 6. When the load voltage approaches the device output voltage, R13 reduces the current, R13 reduces the voltage, Q3's emitter is positively biased and collector is negatively biased, LED4 is turned on and lit, indicating that the charging is complete.

[0087] Example 3, combined Figure 1 , Figure 2 , the device performs charging of DC 24V to DC 12V device, and the process is executed in the order of steps 1, 2, and 3:

[0088] 1. Device set the charging input to 24V DC, the output is 12V DC, and then wait for the DC 24V input access, AC input access is invalid.

[0089] 2. The DC power supply is normally connected, the MOS tube parasitic diode is turned on, the gate-source voltage of the MOS tube is positively biased, the MOS tube is turned on, the DC relay K1 is energized, the normally open contact of K1 is closed, the input indicator light is lit, and the DC input is output stably through the voltage stabilizing module.

[0090] 3. The load is normally connected, the MOS tube is turned on, the DC relay K4 is actuated, and the output polarity indicator light is lit.

[0091] 4. The load end voltage enters the operational amplifier circuit through R14, when the load voltage is not greater than and not less than , the operational amplifier outputs high level, and the DC relay K3 does not act.

[0092] 5. After the parasitic diode is turned on, the MOS tube is turned on, and the device starts to work.

[0093] 6. When the load voltage approaches the device output voltage, R13 reduces the current, R13 reduces the voltage division, Q3's emitter is positively biased and the collector is negatively biased, LED4 is turned on and lit, indicating that the charging is completed.

[0094] The application provides a kind of vehicle-mounted lead-acid battery charging device and method, and the method and approach for realizing the technical scheme are many, the above-mentioned is only preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled in the art, without departing from the principles of the present application, can make several improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application. The components not explicitly described in the embodiment can be realized by existing general technology.

Claims

1. A vehicle-mounted lead-acid battery charging apparatus, characterized by comprising: The device comprises an input protection module, a voltage stabilizing module, an output protection module, and a control and display module. The input protection module realizes the access protection of AC input and DC input; the voltage stabilizing module rectifies AC input and stabilizes DC input and rectified AC input; the output protection module protects the misconnection of a load battery and limits the output current; and the control and display module displays the access of input power and the load battery according to the input and output selection of the device, and controls the input, output and protection limitation of the input protection module, the voltage stabilizing module and the output protection module. The method for charging using the device comprises the following steps: Step 1: setting an input type, wherein the input type comprises DC input and AC input; Step 2: accessing input current according to the input type and performing input judgment; when the input access is normal, an input indicator light is lit, otherwise the input indicator light is not lit; Step 3: setting an output type, wherein the output type comprises DC 12V output and DC 24V output; Step 4: accessing an output load according to the output type and judging the polarity and voltage of the load battery; when the polarity of the load battery is correct, an output polarity indicator light is lit, otherwise the output polarity indicator light is not lit; when the voltage of the load battery is within the allowed range of the set output voltage, an output voltage indicator light is lit, and step 5 is performed; otherwise the output voltage indicator light is not lit; Step 5: when the judgments in step 4 are all correct, the input indicator light, the output polarity indicator light and the output voltage indicator light are all lit, and the device is ready; Step 6: turning on a working switch and performing output according to a set mode; Step 7: judging the voltage of the load battery; if the charging is not completed, the charging is continued, otherwise a charging completion indicator light is lit and the charging is completed. The input protection module comprises an AC input protection circuit and a DC input protection circuit; the input mode is controlled by the control and display module, and the AC input protection circuit and the DC input protection circuit are used according to the input mode.

2. A charging apparatus for a lead-acid battery for a vehicle according to claim 1, characterized by The AC input protection circuit uses a fuse to provide overcurrent protection, and specifically comprises an input selection switch (S1), a second capacitor (C2), a fourth resistor (R4), a fuse (F1) and an AC relay (K2).

3. A vehicle-mounted lead-acid battery charging apparatus according to claim 2, characterized by One end of the input selection switch (S1) is connected to one end of the AC input, the other end of the input selection switch (S1) is connected to the second capacitor (C2), the other end of the second capacitor (C2) is connected to one end of the fuse (F1), the other end of the fuse (F1) is connected to one end of the fourth resistor (R4), and the fourth resistor (R4) is connected to the coil of the AC relay (K2) as an output end of the AC input protection circuit and is connected to one end of the transformer in the voltage stabilizing module, and the other end of the coil of the AC relay (K2) is connected to the other end of the input AC power source and the other end of the transformer in the voltage stabilizing module. ​ 4. A vehicle-mounted lead-acid battery charging apparatus according to claim 3, characterized by The direct current input protection circuit uses the switching characteristic of the PMOS tube for reverse connection protection, and specifically comprises an input selection switch (S1), a first capacitor (C1), a first voltage stabilizing diode (D1), a first PMOS tube (Q1), a first resistor (R1), a second resistor (R2), a third resistor (R3), and a first direct current relay (K1). One end of the input selection switch (S1) is connected to the positive pole of an input direct current power supply, the other end of the input selection switch (S1) is connected to the S end of the first PMOS tube (Q1), the first capacitor (C1), and one end of the first voltage stabilizing diode (D1), the other ends of the first capacitor (C1) and the first voltage stabilizing diode (D1) are connected to one end of the first resistor (R1) and the second resistor (R2), the other end of the first resistor (R1) is connected to the G end of the first PMOS tube (Q1), the other end of the second resistor (R2) is connected to the negative pole of the input direct current power supply and one end of the coil of the first direct current relay (K1), and is connected to a voltage stabilizing circuit in a voltage stabilizing module, the other end of the coil of the first direct current relay (K1) is connected to one end of the third resistor (R3), and the D end of the first PMOS tube (Q1) is connected to the other end of the third resistor (R3) and the voltage stabilizing circuit in the voltage stabilizing module.

5. A vehicle-mounted lead-acid battery charging apparatus according to claim 4, characterized by The output protection module comprises a current limiting circuit, a load access protection module, and a charging monitoring module; wherein the load access protection module comprises a load polarity protection module and a load voltage level protection module.

6. A vehicle-mounted lead-acid battery charging apparatus according to claim 5, characterized by The load polarity protection module uses the switching characteristic of the PMOS tube for reverse connection protection, and comprises a third capacitor (C3), a second voltage stabilizing diode (D2), a second PMOS tube (Q2), an eleventh resistor (R11), a twelfth resistor (R12), a thirteenth resistor (R13), and a fourth direct current relay (K4). One end of the third capacitor (C3) and the second voltage stabilizing diode (D2) is connected to the positive pole of a load battery, and is connected to the S end of the second PMOS tube (Q2), the other ends of the third capacitor (C3) and the second voltage stabilizing diode (D2) are connected to one end of the eleventh resistor (R11) and the twelfth resistor (R12), the other end of the eleventh resistor (R11) is connected to the G end of the second PMOS tube (Q2), the other end of the twelfth resistor (R12) is connected to the negative pole of the load battery and one end of the coil of the fourth direct current relay (K4), and is connected to one port of the charging monitoring module, the other end of the coil of the fourth direct current relay (K4) is connected to one end of the thirteenth resistor (R13), the other end of the thirteenth resistor (R13) is connected to the D end of the second PMOS tube (Q2), and is connected to the other port of the charging monitoring module and one port of the load voltage level protection module.

7. A vehicle-mounted lead-acid battery charging apparatus according to claim 6, characterized by The load voltage level protection module utilizes the operational amplifier to determine the voltage level of the access circuit, and comprises a fourteenth resistor (R14), a fifteenth resistor (R15), a sixteenth resistor (R16), a seventeenth resistor (R17), an eighteenth resistor (R18), a nineteenth resistor (R19), a first operational amplifier (U1A), a second operational amplifier (U1B), a third diode (D3), a fourth diode (D4), and a third DC relay (K3). The one end of the fourteenth resistor (R14) is connected with one port of the load polarity protection module and the charging monitoring module, the one end of the seventeenth resistor (R17) is connected with an input power supply (Vo), the other end is connected with the positive electrode of the second operational amplifier (U1B), and is connected with the one end of the eighteenth resistor (R18), the other end of the eighteenth resistor (R18) is grounded, the other end of the fourteenth resistor (R14) is connected with the negative electrode of the first operational amplifier (U1A) and the second operational amplifier (U1B), the one end of the fifteenth resistor (R15) is connected with the input power supply (Vo), the other end is connected with the negative electrode of the first operational amplifier (U1A), and is connected with the one end of the sixteenth resistor (R16), the other end of the sixteenth resistor (R16) is grounded, the output ends of the first operational amplifier (U1A) and the second operational amplifier (U1B) are respectively connected with the one end of the nineteenth resistor (R19) through the third diode (D3) and the fourth diode (D4), the other end of the nineteenth resistor (R19) is connected with the coil of the third DC relay (K3), and the other end of the coil of the third DC relay (K3) is connected with the charging monitoring module and one end of the current limiting circuit.

8. A vehicle-mounted lead-acid battery charging apparatus according to claim 7, characterized by The charging monitoring module uses the switching characteristic of the triode to perform overcharge protection, and comprises a twenty-first resistor (R21), a twentieth resistor (R20), an LED indicator (LED4), a third triode (Q3), and the third DC relay (K3). The one end of the twentieth resistor (R20) is connected with one end of the load polarity protection module and the current limiting circuit, the other end of the twentieth resistor (R20) is connected with one end of the LED indicator (LED4), the other end of the LED indicator (LED4) is connected with the E electrode of the third triode (Q3), the one end of the twenty-first resistor (R21) is connected with the C electrode of the third triode (Q3), and is connected with one end of the load voltage level protection module and the other end of the load polarity protection module, the other end of the twenty-first resistor (R21) is connected with the B electrode of the third triode (Q3), and is connected with one end of the normally closed contact of the third DC relay (K3), the other end of the normally closed contact of the third DC relay (K3) is connected with the other end of the load voltage level protection module.

9. A vehicle-mounted lead-acid battery charging apparatus according to claim 8, characterized by The control and display module judges the setting and access result of the front-stage input type and the rear-stage load type of the charging device, if the setting and the access result are consistent, the charging device performs the charging strategy, otherwise, the charging device does not start charging.

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