Charging device

Abstract

The utility model relates to the technical field of battery charging, and relates to a charging device. The device comprises a main control module, an identification circuit, a voltage detection circuit and a voltage conversion circuit, the main control module comprises a level output unit, a comparison unit and a main control unit, and the identification circuit is connected in series between the level output unit and the positive electrode of a battery. The level output unit is used for outputting a high level signal and a low level signal and pulling up or pulling down the potential of the positive electrode of the battery through the identification circuit; the comparison unit is used for comparing the potential of the positive electrode of the battery after being pulled up with the voltage after being pulled down, and outputting a first comparison result; the main control unit is used for controlling the level output unit to output a high level signal and a low level signal and identifying whether the battery is a 1.5 V lithium battery according to the first comparison result, and if yes, the voltage conversion circuit is controlled to work in a first charging mode. The 1.5 V lithium battery is identified by adopting the voltage change of the positive electrode of the battery after the positive electrode is pulled up and pulled down, the identification mode is simple, and the cost is relatively low.

Description

Technical Field

[0001] This utility model relates to the field of battery charging technology, and in particular to a charging device. Background Technology

[0002] Commonly used battery types include conventional lithium batteries (3.6V / 3.7V lithium batteries), 1.5V lithium batteries, and nickel-metal hydride batteries. Different battery types require different charging methods.

[0003] Currently, the most common way to charge the three types of batteries mentioned above is to use dedicated chargers for each type. Each charger can only charge one specific type of battery. Charging the wrong type of battery can easily damage the battery and pose a safety hazard. In addition, users need to purchase multiple chargers, resulting in high charging costs. The second method is to use a charger that can identify both regular lithium batteries and nickel-metal hydride batteries to charge the regular lithium batteries and nickel-metal hydride batteries, and to use a dedicated charger to charge the 1.5V lithium batteries.

[0004] The existing chargers have a relatively complex and costly method for identifying 1.5V lithium batteries. Utility Model Content

[0005] The technical problem to be solved by this utility model embodiment is to provide a charging device to solve the problem that the existing charger's identification method for 1.5V lithium batteries is relatively complicated and costly.

[0006] This utility model discloses a charging device for charging a battery, including a main control module, an identification circuit, a voltage detection circuit, and a voltage conversion circuit. The main control module includes a level output unit, a comparison unit, and a main control unit.

[0007] The identification circuit is connected in series between the level output unit and the positive terminal of the battery. The level output unit is used to output high-level signals and low-level signals, and pulls up or down the potential of the positive terminal of the battery through the identification circuit.

[0008] The voltage detection circuit is connected to the positive terminal of the battery, used to detect the voltage of the battery, and transmit the voltage signal to the comparison unit;

[0009] The comparison unit is used to compare the voltage of the battery after its positive terminal potential is pulled up with the voltage after it is pulled down, and output a first comparison result;

[0010] The voltage conversion circuit is used to charge the battery;

[0011] The main control unit is used to control the level output unit to output high-level signals and low-level signals, and to identify whether the battery is a 1.5V lithium battery according to the first comparison result. If so, it controls the voltage conversion circuit to work in the first charging mode.

[0012] Optionally, the identification circuit includes an identification resistor connected in series between the level output unit and the positive terminal of the battery.

[0013] Optionally, the voltage detection circuit includes a first resistor and a filter unit. One end of the first resistor is connected to the positive terminal of the battery, and the other end is connected to the input terminal of the comparison unit and one end of the filter unit. The other end of the filter unit is grounded.

[0014] Optionally, the charging device further includes a current detection circuit, which is used to detect the charging current of the battery and transmit the charging current signal to the main control unit.

[0015] Optionally, the current detection circuit includes a second resistor, a third resistor, and a capacitor. One end of the second resistor is connected to the negative terminal of the battery, and the other end is connected to ground. One end of the capacitor is connected to the main control unit, and the other end is connected to ground. The third resistor is connected in series between the main control unit and the negative terminal of the battery.

[0016] Optionally, the charging device includes a reverse connection protection circuit, which is connected to the positive terminal and negative terminal of the battery and one end of the third resistor.

[0017] Optionally, the reverse connection protection circuit includes a switching transistor, a first voltage divider resistor, and a second voltage divider resistor. The first voltage divider resistor and the second voltage divider resistor are connected in series, and the series connection node is connected to the driving terminal of the switching transistor. The other end of the first voltage divider resistor is connected to the positive terminal of the battery, and the other end of the second voltage divider resistor is connected to one end of the third resistor. The first terminal of the switching transistor is connected to the negative terminal of the battery, and the second terminal is connected to the ground terminal.

[0018] Optionally, the voltage conversion circuit includes a gate driver chip, a switching unit, and an inductor. One end of the inductor is connected to the gate driver chip and the switching unit, and the other end is connected to the positive terminal of the battery. The gate driver chip is connected to the switching unit and the main control unit and is used to output a PWM signal to control the switching unit to turn on or off. The switching unit is also connected to an external power input terminal.

[0019] Optionally, the comparison unit is further configured to compare the voltage of the battery after a pre-charging preset time with a preset voltage value and output a second comparison result. The main control unit is further configured to control the voltage conversion circuit to operate in a second charging mode when it is identified that the battery is not a 1.5V lithium battery, to pre-charge the battery for a preset time, and to identify the battery as a conventional lithium battery or a nickel-metal hydride battery according to the second comparison result, and to control the voltage conversion circuit to operate in a third charging mode or a fourth charging mode.

[0020] Optionally, the main control unit, the comparison unit, and the level output unit are integrated into a control chip. The control chip is provided with signal acquisition pins, control pins, and transmission pins. The signal acquisition pins are connected to the voltage detection circuit and the comparison unit, the control pins are connected to the voltage conversion circuit, and the transmission pins serve as the level output unit.

[0021] Compared with the prior art, the beneficial effects of the charging device provided by this utility model embodiment are as follows: This application sets up an identification circuit, the level output unit of the main control module outputs high-level signals and low-level signals, the identification circuit pulls up or pulls down the potential of the positive terminal of the battery, the voltage detection circuit detects the voltage of the battery, and the comparison unit of the main control module compares the voltage of the battery after its positive terminal is pulled up with that after it is pulled down, and outputs a first comparison result. The first comparison result can characterize the voltage change of the battery after its positive terminal is pulled up and pulled down. Through this change, it can be identified whether the battery is a 1.5V lithium battery. After it is identified as a 1.5V lithium battery, the voltage conversion circuit is controlled to work in the first charging mode. This application uses the voltage change of the positive terminal of the battery after it is pulled up and pulled down to identify a 1.5V lithium battery. The identification method is simple and the cost is low. Attached Figure Description

[0022] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0023] Figure 1 This is a structural block diagram of the charging device provided in an embodiment of the present utility model;

[0024] Figure 2 This is a partial circuit diagram of the charging device provided in an embodiment of this utility model.

[0025] The labels for the attached figures are as follows:

[0026] 110. Main control module; 111. Level output unit; 112. Comparison unit; 113. Main control unit; 120. Identification circuit; 130. Voltage detection circuit; 140. Voltage conversion circuit; 141. Switching unit; 150. Current detection circuit; 160. Reverse connection protection circuit;

[0027] R1, Identification resistor; R2, First resistor; R3, Second resistor; R4, Third resistor; R5, First voltage divider resistor; R6, Second voltage divider resistor; C1, Filter capacitor; C2, Capacitor; Q1, Switching transistor; Q2, First NMOS transistor; Q3, Second NMOS transistor; U1, Gate driver chip; L1, Inductor; ZD1, Diode. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0029] This utility model embodiment provides a charging device for charging a battery, such as... Figure 1 and Figure 2 As shown, the charging device includes a main control module 110, an identification circuit 120, a voltage detection circuit 130, and a voltage conversion circuit 140. The main control module 110 includes a level output unit 111, a comparison unit 112, and a main control unit 113.

[0030] The identification circuit 120 is connected in series between the level output unit 111 and the positive terminal of the battery. The level output unit 111 is used to output high-level signals and low-level signals, and the identification circuit 120 pulls up or down the potential of the positive terminal of the battery.

[0031] The voltage detection circuit 130 is connected to the positive terminal of the battery to detect the battery voltage and transmit the voltage signal to the comparison unit 112.

[0032] The comparison unit 112 is used to compare the voltage of the battery after the potential at its positive terminal is pulled up with the voltage after it is pulled down, and output the first comparison result;

[0033] The voltage conversion circuit 140 is used to charge the battery;

[0034] The main control unit 113 is used to control the level output unit 111 to output high-level signals and low-level signals, and to identify whether the battery is a 1.5V lithium battery according to the first comparison result. If so, it controls the voltage conversion circuit 140 to work in the first charging mode.

[0035] The charging device in this embodiment of the application sets up an identification circuit 120. The level output unit 111 of the main control module 110 outputs high-level signals and low-level signals. The identification circuit 120 pulls up or down the potential of the positive terminal of the battery. The voltage detection circuit 130 detects the voltage of the battery. The comparison unit 112 of the main control module 110 compares the voltage of the battery after its positive terminal is pulled up with that after it is pulled down, and outputs a first comparison result. The first comparison result can characterize the voltage change of the battery after its positive terminal is pulled up and pulled down. Through this change, it can be identified whether the battery is a 1.5V lithium battery. Therefore, this application uses the voltage change of the positive terminal of the battery after it is pulled up and pulled down to identify a 1.5V lithium battery. The identification method is simple and the cost is low.

[0036] If the battery connected to the charging device is a 1.5V lithium battery, since the 1.5V lithium battery has a built-in voltage reduction protection circuit, when the level output unit 111 outputs a high-level signal, it pulls up the potential of the positive terminal of the battery. At this time, the detected battery voltage will be greater than 2.5V. When the level output unit 111 outputs a low-level signal, it pulls down the potential of the positive terminal of the battery. At this time, the detected battery voltage will be lower than 2.0V. That is, the voltage of the battery after its positive terminal potential is pulled up will be greater than the voltage after its positive terminal potential is pulled down. If the battery connected to the charging device is a conventional lithium battery or a nickel-metal hydride battery, when the positive terminal of the battery is pulled up or pulled down, the detected battery voltage will remain unchanged. Therefore, by observing the voltage change after the battery's positive terminal potential is pulled up and pulled down, i.e., the first comparison result, a 1.5V lithium battery can be identified. If it is a 1.5V lithium battery, the first charging mode is used to charge the battery.

[0037] In an optional embodiment of this application, the comparison unit 112 is further configured to compare the voltage of the battery after a pre-charging preset time with a preset voltage value and output a second comparison result. The main control unit 113 is further configured to control the voltage conversion circuit to work in the second charging mode when it is identified that the battery is not a 1.5V lithium battery, to pre-charge the battery for a preset time, and to identify the battery as a conventional lithium battery or a nickel-metal hydride battery according to the second comparison result, and to control the voltage conversion circuit 140 to work in the third charging mode or the fourth charging mode.

[0038] Specifically, if the battery is not a 1.5V lithium battery, the main control unit 113 controls the second charging mode to charge the battery. In the second charging mode, the voltage conversion circuit 140 pre-charges the battery for a preset time. After the preset time, if the battery connected to the charging device is a conventional lithium battery, the detected battery voltage will exceed the preset voltage value, i.e., the maximum voltage of the nickel-metal hydride battery. If the battery connected to the charging device is a nickel-metal hydride battery, the detected battery voltage will not exceed the preset voltage value, i.e., the maximum voltage of the nickel-metal hydride battery. Therefore, the voltage of the battery after the pre-charge preset time is compared with the preset voltage value, and a second comparison result is output. From the second comparison result, conventional lithium batteries and nickel-metal hydride batteries can be identified. The preset time can be set as needed, such as 8 minutes, 9 minutes, or 10 minutes. In the second charging mode, a preset charging current can be used to charge the battery, such as 100 mA or 150 mA, which can be set as needed. In practical applications, the preset voltage value can be 2V. Therefore, this application can distinguish between conventional lithium batteries, 1.5V lithium batteries, and nickel-metal hydride batteries before formal charging, and control the use of the corresponding charging mode to reduce the risk of battery damage. Users do not need to purchase multiple chargers, resulting in lower costs.

[0039] Optionally, the comparison unit 112 may use one comparator to compare the voltage of the battery after it is pulled up at its positive terminal with the voltage after it is pulled down, and output a first comparison result; or use another comparator to compare the voltage of the battery after a preset charging time with a preset voltage value, and output a second comparison result. The main control unit 113 may use logic gate circuits to output control signals based on the first comparison result and the second comparison result to control the voltage conversion circuit 140 to operate in different modes to charge the battery.

[0040] Optionally, the main control unit 113, the comparison unit 112, and the level output unit 111 can also be integrated into a control chip. The control chip is provided with signal acquisition pins, control pins, and transmission pins. The signal acquisition pins are connected to the voltage detection circuit 130 and the comparison unit 112, the control pins are connected to the voltage conversion circuit 140, and the transmission pins serve as the level output unit 111.

[0041] The signal acquisition pin can receive the battery voltage signal V1 detected by the voltage detection circuit 130 and transmit the voltage signal to the comparison unit 112. The control pin outputs a control signal to control the voltage conversion circuit 140 to charge the battery. The transmission pin can output high-level and low-level signals. The main control unit 113, the comparison unit 112, and the level output unit 111 are integrated into a single control chip, simplifying the circuit structure and reducing the footprint. When the charging device includes a current detection circuit 150, the control chip provides another signal acquisition pin, which is connected to the current detection circuit 150 to transmit the charging current signal I1 to the main control unit 113.

[0042] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the identification circuit 120 includes an identification resistor R1, which is connected in series between the level output unit 111 and the positive terminal of the battery.

[0043] By setting the identification resistor R1, the potential of the positive terminal of the battery can be pulled up when the level output unit 111 outputs a high-level signal, and the potential of the positive terminal of the battery can be pulled down when the level output unit 111 outputs a low-level signal. The circuit structure is simple.

[0044] In other embodiments, the identification circuit 120 may also be two resistors connected in series or in parallel and then connected in series between the level output unit 111 and the positive terminal of the battery, which can also realize the pull-up and pull-down of the potential of the positive terminal of the battery.

[0045] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the voltage detection circuit 130 includes a first resistor R2 and a filter unit. One end of the first resistor R2 is connected to the positive terminal of the battery, and the other end is connected to the input terminal of the comparison unit 112 and one end of the filter unit. The other end of the filter unit is grounded.

[0046] By setting the first resistor R2, the comparison unit 112 can obtain the battery voltage, and the filtering unit can filter the voltage signal input to the comparison unit 112 to reduce the risk of damage to the main control chip due to voltage fluctuations.

[0047] Optionally, the filtering unit includes a filtering capacitor C2, with one end of the filtering unit connected to the other end of the first resistor R2 and the input terminal of the comparator unit 112. Using the filtering capacitor C2 allows for filtering with a simpler circuit, reducing the risk of damage to the main control module 110 due to voltage fluctuations.

[0048] refer to Figure 1 and Figure 2In an optional embodiment of this application, the charging device further includes a current detection circuit 150, which is used to detect the charging current of the battery and transmit the charging current signal to the main control unit 113.

[0049] By setting up the current detection circuit 150, the charging current of the battery can be detected, which can assist the main control unit 113 in monitoring the charging current of the battery, preventing the battery from being overcharged or over-discharged, optimizing the charging process, improving charging efficiency, and preventing the battery from overheating, thereby improving the performance, safety and reliability of the charging device.

[0050] Optionally, the current detection circuit 150 includes a second resistor R3, a third resistor R4, and a capacitor C2. One end of the second resistor R3 is connected to the negative terminal of the battery, and the other end is connected to ground. One end of the capacitor C2 is connected to the main control unit 113, and the other end is connected to ground. The third resistor R4 is connected in series between the main control unit 113 and the negative terminal of the battery.

[0051] By setting a second resistor R3, a third resistor R4, and a capacitor C2, the main control unit 113 can detect and acquire the charging current of the battery, and the circuit structure is simple.

[0052] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the charging device includes a reverse connection protection circuit 160, which is connected to the positive terminal, the negative terminal of the battery, and one end of the third resistor R4.

[0053] By setting up the reverse connection protection circuit 160, the reverse connection of the battery can be prevented, thus avoiding damage to the charging device and extending the service life of the charging device.

[0054] Optionally, the reverse connection protection circuit 160 includes a switching transistor Q1, a first voltage divider resistor R5, and a second voltage divider resistor R6. The first voltage divider resistor R5 and the second voltage divider resistor R6 are connected in series, and the series node is connected to the driving terminal of the switching transistor Q1. The other end of the first voltage divider resistor R5 is connected to the positive terminal of the battery, and the other end of the second voltage divider resistor R6 is connected to one end of the third resistor R4. The first terminal of the switching transistor Q1 is connected to the negative terminal of the battery, and the second terminal is connected to the ground terminal.

[0055] When the battery is connected to the charging device with the correct polarity, the first voltage divider resistor R5 and the second voltage divider resistor R6 can divide the voltage to obtain a suitable voltage, driving the switch Q1 to conduct, connecting the negative terminal of the battery to the resistor, allowing the battery to charge normally. When the battery is connected to the charging device in reverse, the switch Q1 is turned off, breaking the path between the negative terminal of the battery and the third resistor R4. The battery will not form a circuit in the charging device, thus preventing damage to the charging device. Therefore, the reverse connection protection circuit 160 composed of the switch Q1, the first voltage divider resistor R5, and the second voltage divider resistor R6 can effectively prevent damage to the charging device caused by reverse battery connection.

[0056] In a specific implementation, the switch Q1 can be an NMOS transistor. The gate of the NMOS transistor is used as the driving terminal of the switch Q1, the drain is used as the first terminal of the switch Q1, and the source is used as the second terminal of the switch Q1.

[0057] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the voltage conversion circuit 140 includes a gate driver chip U1, a switching unit 141, and an inductor L1. One end of the inductor L1 is connected to the gate driver chip U1 and the switching unit 141, and the other end is connected to the positive terminal of the battery. The gate driver chip U1 is connected to the switching unit 141 and the main control unit 113, and is used to output a PWM signal to control the switching unit 141 to turn on or off. The switching unit 141 is also connected to the external power input terminal VO.

[0058] The gate driver chip U1 can output a PWM signal under the control of the main control unit 113 to control the switching unit 141 to turn on and off, so as to transfer the power of the external power supply to the inductor L1, so that the inductor L1 stores and releases energy to charge the connected battery.

[0059] The gate driver chip U1 has a high degree of integration, which simplifies the circuit structure and reduces the size occupied by the circuit.

[0060] Optionally, the switching unit 141 includes a first NMOS transistor Q2 and a second NMOS transistor Q3. The gate driver chip U1 is provided with a high-side output pin HO, a low-side output pin LO, a switch pin SW, an input pin IN, and an enable pin EN. The high-side output pin HO is connected to the gate of the first NMOS transistor Q2, the low-side output pin LO is connected to the gate of the second NMOS transistor Q3, the switch pin SW is connected to the source of the first NMOS transistor Q2, the drain of the second NMOS transistor Q3, and one end of the inductor L1. The input pin IN and the enable pin EN are both connected to the main control unit 113. The drain of the first NMOS transistor Q2 is connected to the external power supply input terminal, and the source of the second NMOS transistor Q3 is connected to the ground terminal.

[0061] The high-side output pin HO of the gate driver chip U1 is used to output a PWM signal to control the conduction and cutoff of the first NMOS transistor Q2. The low-side output pin LO is used to output a PWM signal to control the conduction and cutoff of the second NMOS transistor Q3. The switch pin SW is used to synchronize the switching actions of the two NMOS transistors. The input pin IN is used to receive the control signal from the main control unit 113. The enable pin EN is used to receive the enable signal from the main control unit 113.

[0062] During the energy storage phase of inductor L1, the high-side output pin HO of the gate driver chip U1 outputs a high level, and the low-side output pin LO outputs a low level. The first NMOS transistor Q2 is turned on, and the second NMOS transistor Q3 is turned off. The external power supply voltage powers the load through the first NMOS transistor Q2 and inductor L1, while inductor L1 stores energy. During the energy release phase of inductor L1, the high-side output pin HO of the gate driver chip U1 outputs a low level, and the low-side output pin LO outputs a high level. The first NMOS transistor Q2 is turned off, and the second NMOS transistor Q3 is turned on, allowing inductor L1 to release energy. The gate driver chip U1 controls the charging and discharging process of inductor L1 by adjusting the duty cycle of the PWM signals on the high-side output pin HO and the low-side output pin LO, thereby regulating the output voltage and operating in different charging modes to charge different types of batteries.

[0063] In practice, the gate driver chip U1 can be a chip with the model number BDR2L00.

[0064] Furthermore, the voltage conversion circuit 140 also includes a diode ZD1, the positive terminal of which is connected to the switch pin SW, and the negative terminal is connected to the source of the first NMOS transistor Q2, the drain of the second NMOS transistor Q3, and one end of the inductor L1.

[0065] By setting diode ZD1, current backflow to the gate driver chip U1 can be prevented, thus preventing damage to the gate driver chip U1 and ensuring the normal operation of the charging device.

[0066] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. A charging device for charging a battery, characterized by, The charging device comprises a main control module, an identification circuit, a voltage detection circuit and a voltage conversion circuit, the main control module comprises a level output unit, a comparison unit and a main control unit, wherein, the identification circuit is connected in series between the level output unit and the positive electrode of the battery, the level output unit is used for outputting high-level signals and low-level signals, and the potential of the positive electrode of the battery is pulled up or pulled down through the identification circuit; the voltage detection circuit is connected to the positive electrode of the battery, used for detecting the voltage of the battery and transmitting the voltage signal to the comparison unit; the comparison unit is used for comparing the voltage of the battery after the potential of the positive electrode is pulled up with the voltage after the potential of the positive electrode is pulled down, and outputting a first comparison result; the voltage conversion circuit is used for charging the battery; the main control unit is used for controlling the level output unit to output high-level signals and low-level signals, and identifying whether the battery is a 1.5V lithium battery according to the first comparison result, and if so, controlling the voltage conversion circuit to work in a first charging mode.

2. The charging device of claim 1, wherein, The identification circuit comprises an identification resistor connected in series between the level output unit and the positive electrode of the battery.

3. The charging device of claim 1, wherein, The voltage detection circuit comprises a first resistor and a filter unit, one end of the first resistor is connected to the positive electrode of the battery, the other end is connected to the input end of the comparison unit and one end of the filter unit, and the other end of the filter unit is grounded.

4. The charging device of claim 1, wherein, The charging device further comprises a current detection circuit, which is used for detecting the charging current of the battery and transmitting the charging current signal to the main control unit.

5. The charging device of claim 4, wherein, The current detection circuit comprises a second resistor, a third resistor and a capacitor, one end of the second resistor is connected to the negative electrode of the battery, the other end is connected to the ground end, one end of the capacitor is connected to the main control unit, the other end is connected to the ground end, and the third resistor is connected in series between the main control unit and the negative electrode of the battery.

6. The charging device of claim 5, wherein, The charging device comprises an anti-reverse connection circuit, which is connected to the positive electrode and the negative electrode of the battery and one end of the third resistor.

7. The charging device of claim 6, wherein, The anti-reverse connection circuit comprises a switch tube, a first voltage dividing resistor and a second voltage dividing resistor, the first voltage dividing resistor and the second voltage dividing resistor are connected in series, the series node is connected to the driving end of the switch tube, the other end of the first voltage dividing resistor is connected to the positive electrode of the battery, the other end of the second voltage dividing resistor is connected to one end of the third resistor, the first end of the switch tube is connected to the negative electrode of the battery, and the second end is connected to the ground end.

8. The charging device of claim 1, wherein, The voltage conversion circuit comprises a gate drive chip, a switching unit and an inductor, one end of the inductor is connected to the gate drive chip and the switching unit, the other end is connected to the positive electrode of the battery, the gate drive chip is connected to the switching unit and the main control unit, used for outputting a PWM signal to control the conduction or cutoff of the switching unit, and the switching unit is further connected to an external power input end.

9. The charging device of claim 1, wherein, The comparison unit is also configured to compare the voltage of the battery after pre-charging for a preset time with a preset voltage value, and output a second comparison result; and the control unit is further configured to, in the case that the battery is not a 1.5V lithium battery, control the voltage conversion circuit to work in a second charging mode, pre-charge the battery for a preset time, and according to the second comparison result, identify whether the battery is a conventional lithium battery or a nickel-hydrogen battery, and control the voltage conversion circuit to work in a third charging mode or a fourth charging mode.

10. The charging device according to any one of claims 1 to 9, characterized in that, The control unit, the comparison unit and the level output unit are integrally arranged in a control chip, the control chip is provided with a signal acquisition pin, a control pin and a transmission pin, the signal acquisition pin is connected with the voltage detection circuit and the comparison unit, the control pin is connected with the voltage conversion circuit, and the transmission pin serves as the level output unit.

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