A charging circuit and a charging method for a nickel-cadmium or nickel-hydrogen battery pack

Abstract

The application discloses a charging circuit and a charging method for a nickel-cadmium and nickel-hydrogen battery pack, and relates to the technical field of battery charging. The circuit comprises a charging input module, an input protection circuit, a charging management module and a battery pack selection circuit. The charging input module is used for inputting a charging current into the charging battery. The input protection circuit is used for overcurrent protection of the input charging current, so as to realize input protection function. The charging management module is used for managing the charging current input by the charging input module. The battery pack selection circuit comprises a 1-16 section battery pack, and is used for ensuring that a charging management chip accurately identifies the voltage of a nickel-cadmium / nickel-hydrogen battery pack, so as to realize matched charging. The nickel-cadmium / nickel-hydrogen battery selection circuit is used for controlling the charging parameters of the charging management chip, and is suitable for two different types of batteries, namely, nickel-cadmium and nickel-hydrogen batteries. The nickel-cadmium / nickel-hydrogen battery pack is used for receiving the charging current and completing the charging operation. The application realizes a 1-16 section nickel-cadmium or nickel-hydrogen series connection battery pack charging circuit, and can meet the charging application scenarios of the battery pack rated voltage of 1.2VDC-19.2VDC.

Description

Technical Field

[0001] This invention relates to the field of battery charging technology, and specifically to a charging circuit and charging method for nickel-cadmium and nickel-metal hydride battery packs. Background Technology

[0002] With the development of modern battery technology, lithium battery packs have become the most widely used battery packs. However, nickel-cadmium batteries and nickel-metal hydride batteries still have irreplaceable application advantages in certain situations due to their low cost, excellent high-current discharge capability, and good low-temperature performance. For example, they are used as power batteries for certain special equipment, batteries for emergency lighting systems, airborne aviation batteries, digital products, and children's toys.

[0003] Because different battery pack series connection schemes are used in different application scenarios, the battery pack may be implemented by connecting one, two, three, four or even more cells in series. In this case, the rated voltage of the battery pack is different. When designing the battery pack charging and discharging maintenance scheme, a separate charging circuit needs to be designed. Repeated scheme design can easily lead to waste of human and material resources. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a charging circuit and charging method for nickel-cadmium and nickel-metal hydride battery packs.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] In a first aspect, this application discloses a charging circuit for nickel-cadmium and nickel-metal hydride battery packs, comprising:

[0007] A charging input module, wherein the input terminal of the input module is connected to a charging power supply for supplying charging current to the rechargeable battery;

[0008] An input protection circuit is provided, the input terminal of which is connected to the charging input module, for overcurrent protection of the input charging current, thereby realizing the input protection function.

[0009] A charging management module, the input terminals of which are respectively connected to an input protection circuit and a battery pack selection circuit, the charging management module includes a charging management chip, the charging management chip managing the charging current input by the charging input module;

[0010] A battery pack selection circuit, the input of which is connected to a nickel-cadmium / nickel-metal hydride battery pack, the battery pack selection circuit including 1-16 battery cells, is used to ensure that the charging management chip accurately identifies the voltage of the nickel-cadmium / nickel-metal hydride battery pack and achieves matching charging;

[0011] A nickel-cadmium / nickel-metal hydride battery selection circuit, the output of which is connected to the charging management module, is used to control the charging parameters of the charging management chip and is compatible with two different types of batteries, nickel-cadmium and nickel-metal hydride.

[0012] A nickel-cadmium / nickel-metal hydride battery pack, the input terminal of which is connected to the charging management module to receive the charging current output by the charging management module and complete the charging operation.

[0013] Based on the first aspect, the input protection circuit includes: a first diode D1 and a first fuse F1, the input terminal of the first diode D1 is connected to the charging input module, the output terminal of the first diode D1 is connected to the first fuse F1, a first node is also provided between the output terminal of the first diode D1 and the first fuse F1, and a first capacitor C1 is also connected between the first node and the charging input module.

[0014] Based on the first aspect, a PWM synchronous buck current source control circuit is further provided between the first fuse F1 and the charging management chip. The PWM synchronous buck current source control circuit includes a second diode D2, a first MOSFET Q1, a second MOSFET Q2, and a twenty-first resistor R21. After the first fuse F1 is connected to the second diode D2, it is connected to the VCC pin of the charging management chip. A fifth resistor R5 and a second capacitor C2 are also connected in parallel across the second diode D2. The second diode D2 is also connected to the source of the first MOSFET Q1. The drain of transistor Q1 is connected to the drain of transistor Q2. The source of transistor Q2 is grounded. The gates of transistors Q1 and Q2 are connected to the charging management chip. A second node is provided between the drains of transistors Q1 and Q2. The second node is connected to the first inductor L1 and then to the twenty-first resistor R21. The two ends of the twenty-first resistor R21 are also connected to the SENCE pin and BAT pin of the charging management chip, respectively. The twenty-first resistor R21 is also connected to the positive terminal of the nickel-cadmium / nickel-metal hydride battery pack.

[0015] Based on the first aspect, the resistance value of the 21st resistor R21 is 100mV / charging current.

[0016] Based on the first aspect, an indicator circuit is further provided between the input protection circuit and the charging management chip. The indicator circuit includes a ninth resistor R9, an eleventh resistor R11, and a fifteenth resistor R15. The input protection circuit is connected to the ninth resistor R9, the eleventh resistor R11, and the fifteenth resistor R15 respectively. The ninth resistor R9 is connected to the first indicator LED1 and then to the FAULT pin of the charging management chip. The eleventh resistor R11 is connected to the second indicator LED2 and then to the CHRG pin of the charging management chip. The fifteenth resistor R15 is connected to the third indicator LED3 and then to the READY pin of the charging management chip.

[0017] Based on the first aspect, the battery pack selection circuit includes: a first 8-way encoder switch SW1 and a second 8-way encoder switch SW2. The second 8-way encoder switch SW2 is connected to the positive terminal of the nickel-cadmium / nickel-metal hydride battery pack. The first 8-way encoder switch SW1 is connected to the tenth resistor R10 and then to the second 8-way encoder switch SW2. The first 8-way encoder switch SW1 and the second 8-way encoder switch SW2 are also connected to the twenty-second resistor R22. The twenty-second resistor R22 is also connected between the VCDIV pin and the VCELL pin of the charging management chip.

[0018] Based on the first aspect, the first 8-way encoder switch SW1 and the second 8-way encoder switch SW2 are also respectively connected to a resistor network;

[0019] The resistor network of the first 8-channel encoder switch SW1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The first pin of the first 8-channel encoder switch SW1 is connected to the eighth pin of the first 8-channel encoder switch SW1 after the third resistor R3, the second resistor R2, the first resistor R1, the fourth resistor R4, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are connected in series. A third node is provided between the second resistor R2 and the third resistor R3, and this third node is connected to the second pin of the first 8-channel encoder switch SW1. A resistor is provided between the first resistor R1 and the second resistor R2. There is a fourth node, which is connected to the third pin of the first 8-channel encoder switch SW1; a fifth node is provided between the first resistor R1 and the fourth resistor R4, which is connected to the fourth pin of the first 8-channel encoder switch SW1; a sixth node is provided between the fourth resistor R4 and the sixth resistor R6, which is connected to the fifth pin of the first 8-channel encoder switch SW1; a seventh node is provided between the sixth resistor R6 and the seventh resistor R7, which is connected to the sixth pin of the first 8-channel encoder switch SW1; an eighth node is provided between the seventh resistor R7 and the eighth resistor R8, which is connected to the seventh pin of the first 8-channel encoder switch SW1.

[0020] The resistor network of the second 8-channel encoder switch SW2 includes a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a sixteenth resistor R16, an eighteenth resistor R18, a nineteenth resistor R19, and a twentieth resistor R20. The first pin of the second 8-channel encoder switch SW2 is connected to the eighth pin of the second 8-channel encoder switch SW2 after these resistors are connected in series. A ninth node is provided between the twelfth resistor R12 and the fourteenth resistor R14, and this ninth node is connected to the second pin of the second 8-channel encoder switch SW2. The fourteenth resistor R14 and the thirteenth resistor R15... A tenth node is set between resistors R13 and R16, and the tenth node is connected to the third pin of the second 8-way encoder switch SW2; an eleventh node is set between resistors R13 and R16, and the eleventh node is connected to the fourth pin of the second 8-way encoder switch SW2; a twelfth node is set between resistors R16 and R18, and the twelfth node is connected to the fifth pin of the second 8-way encoder switch SW2; a thirteenth node is set between resistors R18 and R19, and the thirteenth node is connected to the sixth pin of the second 8-way encoder switch SW2; a fourteenth node is set between resistors R19 and R20, and the fourteenth node is connected to the seventh pin of the second 8-way encoder switch SW2.

[0021] A fifteenth node is provided between the eighth resistor R8 and the eighth pin of the first 8-way encoding switch SW1, and a sixteenth node is provided between the twelfth resistor R12 and the first pin of the second 8-way encoding switch SW2; the two ends of the tenth resistor R10 are respectively connected to the fifteenth node and the sixteenth node.

[0022] Based on the first aspect, the resistance value of the second twelfth resistor R22 is the resistance value of the resistor network multiplied by (n-1), where n represents the number of battery cells being charged in the nickel-cadmium / nickel-metal hydride battery pack.

[0023] Based on the first aspect, the nickel-cadmium / nickel-metal hydride battery selection circuit includes a 1-channel encoder switch SW3, which is connected to the CHEM pin of the charging management chip.

[0024] Secondly, this application discloses a charging method for a charging circuit for a nickel-cadmium / nickel-metal hydride battery pack as described above, comprising the following steps:

[0025] S1. Based on the battery chemistry of the battery pack to be charged, operate the 1-way encoding switch SW3 to control the state of the CHEM pin of the charging management chip. If the battery pack to be charged is a nickel-metal hydride battery, then the CHEM pin of the charging management chip is grounded; if the battery pack to be charged is a nickel-cadmium battery, then the CHEM pin of the charging management chip is left floating.

[0026] S2. Based on the number of battery cells connected in series in the battery pack to be charged, adjust the first 8-channel encoding switch SW1 and the second 8-channel encoding switch SW2 to the corresponding number of cells connected in series.

[0027] S3. Connect the battery pack to be charged to the charging circuit. At this time, the third indicator LED3 in the indicator circuit is lit, while the first indicator LED1 and the second indicator LED2 are off.

[0028] S4. Connect the charging input module to charge the battery pack. Input the voltage. At this time, the third indicator LED3 and the second indicator LED2 will be lit, and the first indicator LED1 will be off. When the second indicator LED2 turns off and the third indicator LED3 turns on, it means that the battery pack to be charged is fully charged.

[0029] The beneficial effects of this invention are:

[0030] 1) This application can be used to charge nickel-cadmium battery packs or nickel-metal hydride battery packs as needed, or to manually select 1-16 nickel-cadmium or nickel-metal hydride series battery packs for charging as needed.

[0031] 2) This application applies to charging solutions for nickel-cadmium or nickel-metal hydride battery packs with a rated voltage of 1.2VDC to 19.2VDC and a battery capacity of ≤6AH.

[0032] 3) The charging current of this application can be configured to C / 2 to 2C, and the maximum charging current can reach 3A. It can automatically trickle charge deeply discharged batteries. Without the intervention of MCU detection, it can complete the detection and indication of battery access status, system charging status (including charging in progress and charging completed) and charging fault status. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a charging circuit for a nickel-cadmium nickel-metal hydride battery pack according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the charging circuit for a nickel-cadmium nickel-metal hydride battery pack according to an embodiment of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] See Figures 1-2 This application discloses a charging circuit for nickel-cadmium and nickel-metal hydride battery packs, comprising:

[0037] A charging input module, wherein the input terminal of the input module is connected to a charging power supply for supplying charging current to the rechargeable battery;

[0038] An input protection circuit is provided, the input terminal of which is connected to the charging input module, for overcurrent protection of the input charging current, thereby realizing the input protection function.

[0039] A charging management module, the input terminals of which are respectively connected to an input protection circuit and a battery pack selection circuit, the charging management module includes a charging management chip, the charging management chip managing the charging current input by the charging input module;

[0040] A battery pack selection circuit, the input of which is connected to a nickel-cadmium / nickel-metal hydride battery pack, the battery pack selection circuit including 1-16 battery cells, is used to ensure that the charging management chip accurately identifies the voltage of the nickel-cadmium / nickel-metal hydride battery pack and achieves matching charging;

[0041] A nickel-cadmium / nickel-metal hydride battery selection circuit, the output of which is connected to the charging management module, is used to control the charging parameters of the charging management chip and is compatible with two different types of batteries, nickel-cadmium and nickel-metal hydride.

[0042] A nickel-cadmium / nickel-metal hydride battery pack, the input terminal of which is connected to the charging management module to receive the charging current output by the charging management module and complete the charging operation.

[0043] Specifically, the input protection circuit includes: a first diode D1 and a first fuse F1. The input terminal of the first diode D1 is connected to the charging input module, and the output terminal of the first diode D1 is connected to the first fuse F1. A first node is also provided between the output terminal of the first diode D1 and the first fuse F1, and a first capacitor C1 is also connected between the first node and the charging input module.

[0044] For example, in this embodiment, the charging input module uses 33VDC for charging. The input voltage is filtered by the filter capacitor (C1) after being protected against reverse connection by the SS34 Schottky diode (D1), and then protected against overcurrent by the one-time fuse (F1), thus realizing the input protection function of the entire charging scheme.

[0045] Specifically, a PWM synchronous buck current source control circuit is also provided between the first fuse F1 and the charging management chip. The PWM synchronous buck current source control circuit includes a second diode D2, a first MOSFET Q1, a second MOSFET Q2, and a 21st resistor R21. After the first fuse F1 is connected to the second diode D2, it is connected to the VCC pin of the charging management chip. The second diode D2 is also connected in parallel with a fifth resistor R5 and a second capacitor C2. The second diode D2 is also connected to the source of the first MOSFET Q1. The drain of the first MOSFET Q1 is connected to the drain of the second MOSFET Q2. The source of the second MOSFET Q2 is grounded. The gates of the first MOSFET Q1 and the second MOSFET Q2 are respectively connected to the charging management chip. A second node is provided between the drain of the first MOSFET Q1 and the drain of the second MOSFET Q2. The second node is connected to the first inductor L1 and then to the 21st resistor R21. The two ends of the 21st resistor R21 are also connected to the SENCE pin and the BAT pin of the charging management chip, respectively. The 21st resistor R21 is also connected to the positive terminal of the nickel-cadmium / nickel-metal hydride battery pack.

[0046] For example, the voltage from the input protection circuit is isolated and filtered by a resistor (R5), a Schottky diode (D2), and a filter capacitor (C2) before being sent to the LTC4010 charging management chip (U1) for power supply. At the same time, it forms a PWM synchronous buck current source controller with a nominal frequency of 550KHz, together with an AO3401A type NMOS transistor (Q1), an AO3400 type PMOS transistor (Q2), a power inductor (L1), and a sampling resistor (R21). The current of its current source is the battery charging current, and the maximum charging current can reach 3A. The charging current can be adjusted by adjusting the resistance value of the sampling resistor (R21). The sampling resistor should be a high-precision, low-temperature drift, high-power sampling resistor to improve the reliability and stability of the charging circuit.

[0047] Specifically, the resistance value of the 21st resistor R21 is 100mV / charging current.

[0048] For example, the charging current configured in the circuit is inversely proportional to the sampling resistor (R21). By selecting and adapting the sampling resistor (R21), it is possible to charge nickel-cadmium or nickel-metal hydride battery packs with a rated voltage of 1.2VDC to 19.2VDC and a battery capacity ≤6AH, applicable to most nickel-cadmium or nickel-metal hydride battery pack charging applications on the market. For example, for a charging scheme for a 2AH nickel-cadmium battery pack, the designed charging current is 1C, i.e., a constant current charging current of 2A. In this application scenario, a sampling resistor value of 0.05Ω is sufficient.

[0049] Specifically, an indicator circuit is also provided between the input protection circuit and the charging management chip. The indicator circuit includes a ninth resistor R9, an eleventh resistor R11, and a fifteenth resistor R15. The input protection circuit is connected to the ninth resistor R9, the eleventh resistor R11, and the fifteenth resistor R15 respectively. The ninth resistor R9 is connected to the first indicator LED1 and then to the FAULT pin of the charging management chip. The eleventh resistor R11 is connected to the second indicator LED2 and then to the CHRG pin of the charging management chip. The fifteenth resistor R15 is connected to the third indicator LED3 and then to the READY pin of the charging management chip.

[0050] For example, the voltage from the input protection circuit is further limited by current-limiting resistors (R9, R11, R15) and then connected to the FAULT, CHRG, and READY pins of the LTC4010 charging management chip (U1) via LED indicators (LED1, LED2, LED3) to indicate the battery charging status. The correspondence between the system operating status and the indicator lights is shown in Table 1.

[0051] Table 1: Correspondence between system operating status and indicator lights

[0052]

[0053] Specifically, the battery pack selection circuit includes: a first 8-way encoder switch SW1 and a second 8-way encoder switch SW2. The second 8-way encoder switch SW2 is connected to the positive terminal of the nickel-cadmium / nickel-metal hydride battery pack. The first 8-way encoder switch SW1 is connected to the tenth resistor R10 and then to the second 8-way encoder switch SW2. The first 8-way encoder switch SW1 and the second 8-way encoder switch SW2 are also connected to the twenty-second resistor R22. The twenty-second resistor R22 is also connected between the VCDIV pin and the VCELL pin of the charging management chip.

[0054] For example, the output of the PWM current source controller is connected to the BAT pin of the LTC4010 and the positive terminal of the battery pack being charged via a sampling resistor (R21). The negative terminal of the battery pack is connected to the GND of the charging current, thus completing the charging current loop.

[0055] Specifically, the first 8-channel encoder switch SW1 and the second 8-channel encoder switch SW2 are also connected to resistor networks. The resistor network of the first 8-channel encoder switch SW1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The first pin of the first 8-channel encoder switch SW1 is connected to the eighth pin of the first 8-channel encoder switch SW1 after the third resistor R3, the second resistor R2, the first resistor R1, the fourth resistor R4, the sixth resistor R6, the seventh resistor R7, and the eighth resistor R8 are connected in series. A third node is provided between the second resistor R2 and the third resistor R3, and the third node is connected to the second pin of the first 8-channel encoder switch SW1. A fourth node is provided between the first resistor R1 and the second resistor R2, and the fourth node is connected to the third pin of the first 8-channel encoder switch SW1; a fifth node is provided between the first resistor R1 and the fourth resistor R4, and the fifth node is connected to the fourth pin of the first 8-channel encoder switch SW1; a sixth node is provided between the fourth resistor R4 and the sixth resistor R6, and the sixth node is connected to the fifth pin of the first 8-channel encoder switch SW1; a seventh node is provided between the sixth resistor R6 and the seventh resistor R7, and the seventh node is connected to the sixth pin of the first 8-channel encoder switch SW1; an eighth node is provided between the seventh resistor R7 and the eighth resistor R8, and the eighth node is connected to the seventh pin of the first 8-channel encoder switch SW1.

[0056] The ninth to sixteenth pins of the first 8-channel encoder switch SW1 are connected to the serial port terminals of the ninth to sixteenth sections respectively, and then connected in parallel with the twenty-second resistor R22;

[0057] The resistor network of the second 8-channel encoder switch SW2 includes a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a sixteenth resistor R16, an eighteenth resistor R18, a nineteenth resistor R19, and a twentieth resistor R20. The first pin of the second 8-channel encoder switch SW2 is connected to the eighth pin of the second 8-channel encoder switch SW2 after these resistors are connected in series. A ninth node is provided between the twelfth resistor R12 and the fourteenth resistor R14, and this ninth node is connected to the second pin of the second 8-channel encoder switch SW2. The fourteenth resistor R14 and the thirteenth resistor R15... A tenth node is set between resistors R13 and R16, and the tenth node is connected to the third pin of the second 8-way encoder switch SW2; an eleventh node is set between resistors R13 and R16, and the eleventh node is connected to the fourth pin of the second 8-way encoder switch SW2; a twelfth node is set between resistors R16 and R18, and the twelfth node is connected to the fifth pin of the second 8-way encoder switch SW2; a thirteenth node is set between resistors R18 and R19, and the thirteenth node is connected to the sixth pin of the second 8-way encoder switch SW2; a fourteenth node is set between resistors R19 and R20, and the fourteenth node is connected to the seventh pin of the second 8-way encoder switch SW2.

[0058] The ninth to sixteenth pins of the second 8-channel encoding switch SW2 are connected to the single-section to eight-section serial port terminals respectively, and then connected in parallel with the twenty-second resistor R22;

[0059] A fifteenth node is provided between the eighth resistor R8 and the eighth pin of the first 8-way encoding switch SW1, and a sixteenth node is provided between the twelfth resistor R12 and the first pin of the second 8-way encoding switch SW2; the two ends of the tenth resistor R10 are respectively connected to the fifteenth node and the sixteenth node.

[0060] For example, the battery pack selection circuit consists of two 8-way coded switches (SW1, SW2) and an external resistor network. Specifically, it is implemented by turning on either SW1 or SW2 according to the number of battery cells connected in series. The battery voltage is then divided by the resistor network and the voltage divider resistor (R22) connected between the VCDIV and VCELL pins of the LTC4010 charging management chip to provide a voltage value.

[0061] For example, the resistance of the second twelfth resistor R22 is the resistance of the resistor network multiplied by (n-1), where n represents the number of battery cells being charged in the nickel-cadmium / nickel-metal hydride battery pack.

[0062] Specifically, in this embodiment, the voltage divider resistor (R22) is set to 10kΩ. As can be seen from the above formula, the voltage divider resistor connected to the resistor network in the single-cell battery pack charging scheme is 0Ω, that is, the positive terminal of the battery pack is directly shorted to the VCELL pin. The voltage divider resistors connected to the resistor network for 2 to 16 cells should be 10kΩ, 20kΩ, 30kΩ, 40kΩ...150kΩ. Since some of the listed resistance values ​​are non-nominal values, it is necessary to use custom resistors or splice multiple resistors to match a relatively accurate resistance value, which is quite troublesome. Therefore, it is designed here to connect 15 10kΩ resistors in series, and connect the series connection between the resistors to one channel of two 8-way encoder switches. The other ends of the two encoder switches are connected in parallel to the VCELL pin of the LTC4010 charging management chip.

[0063] Specifically, the nickel-cadmium / nickel-metal hydride battery selection circuit includes a 1-channel encoder switch SW3, which is connected to the CHEM pin of the charging management chip.

[0064] For example, the CHEM pin of the chip is the battery chemistry selection pin. When the CHEM pin is connected to GND, it selects the fast charging termination parameter for NiMH batteries. When a voltage greater than 2.85V is applied to the CHEM pin or it is left floating, it selects the NiCd battery parameter. In this embodiment, a single-channel coded switch is used to switch the chip's CHEM pin between ground and floating to select between NiCd and NiMH batteries.

[0065] This application also discloses a charging method for a charging circuit for a nickel-cadmium nickel-metal hydride battery pack as described above, comprising the following steps:

[0066] S1. Based on the battery chemistry of the battery pack to be charged, operate the 1-way encoding switch SW3 to control the state of the CHEM pin of the charging management chip. If the battery pack to be charged is a nickel-metal hydride battery, then the CHEM pin of the charging management chip is grounded; if the battery pack to be charged is a nickel-cadmium battery, then the CHEM pin of the charging management chip is left floating.

[0067] S2. Based on the number of battery cells connected in series in the battery pack to be charged, adjust the first 8-channel encoding switch SW1 and the second 8-channel encoding switch SW2 to the corresponding number of cells connected in series.

[0068] S3. Connect the battery pack to be charged to the charging circuit. At this time, the third indicator LED3 in the indicator circuit is lit, while the first indicator LED1 and the second indicator LED2 are off.

[0069] S4. Connect the charging input module to charge the battery pack. Input the voltage. At this time, the third indicator LED3 and the second indicator LED2 will be lit, and the first indicator LED1 will be off. When the second indicator LED2 turns off and the third indicator LED3 turns on, it means that the battery pack to be charged is fully charged.

[0070] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A charging circuit for a nickel-cadmium or nickel-hydrogen battery pack, characterized by comprising: include: A charging input module, wherein the input terminal of the input module is connected to a charging power supply for supplying charging current to the rechargeable battery; An input protection circuit is provided, the input terminal of which is connected to the charging input module, for overcurrent protection of the input charging current, thereby realizing the input protection function. A charging management module, the input terminals of which are respectively connected to an input protection circuit and a battery pack selection circuit, the charging management module includes a charging management chip, the charging management chip managing the charging current input by the charging input module; A battery pack selection circuit, the input of which is connected to a nickel-cadmium / nickel-metal hydride battery pack, the battery pack selection circuit including 1-16 battery cells, is used to ensure that the charging management chip accurately identifies the voltage of the nickel-cadmium / nickel-metal hydride battery pack and achieves matching charging; A nickel-cadmium / nickel-metal hydride battery selection circuit, the output of which is connected to the charging management module, is used to control the charging parameters of the charging management chip and is compatible with two different types of batteries, nickel-cadmium and nickel-metal hydride. A nickel-cadmium / nickel-metal hydride battery pack, wherein the input terminal of the nickel-cadmium / nickel-metal hydride battery pack is connected to the charging management module to receive the charging current output by the charging management module and complete the charging operation; The battery pack selection circuit includes a first 8-way encoder switch SW1 and a second 8-way encoder switch SW2. The first 8-way encoder switch SW1 is connected to the tenth resistor R10 and then to the second 8-way encoder switch SW2. The first 8-way encoder switch SW1 and the second 8-way encoder switch SW2 are also connected to a resistor network. The resistor network of the first 8-channel encoder switch SW1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8. The first pin of the first 8-channel encoder switch SW1 is connected to the eighth pin of the first 8-channel encoder switch SW1 after the third resistor R3, second resistor R2, first resistor R1, fourth resistor R4, sixth resistor R6, seventh resistor R7, and eighth resistor R8 are connected in series. A third node is provided between the second resistor R2 and the third resistor R3, and this third node is connected to the first 8-channel encoder switch SW1. The second pin is connected; a fourth node is provided between the first resistor R1 and the second resistor R2, and the fourth node is connected to the third pin of the first 8-way encoder switch SW1; a fifth node is provided between the first resistor R1 and the fourth resistor R4, and the fifth node is connected to the fourth pin of the first 8-way encoder switch SW1; a sixth node is provided between the fourth resistor R4 and the sixth resistor R6, and the sixth node is connected to the fifth pin of the first 8-way encoder switch SW1; a seventh node is provided between the sixth resistor R6 and the seventh resistor R7, and the seventh node is connected to the sixth pin of the first 8-way encoder switch SW1. An eighth node is provided between the seventh resistor R7 and the eighth resistor R8, and the eighth node is connected to the seventh pin of the first 8-way encoding switch SW1. The resistance network of the second 8-way encoding switch SW2 includes a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a sixteenth resistor R16, an eighteenth resistor R18, a nineteenth resistor R19, and a twentieth resistor R20. The first pin of the second 8-way encoding switch SW2 is connected with the eighth pin of the second 8-way encoding switch SW2 in sequence after the twelfth resistor R12, the fourteenth resistor R14, the thirteenth resistor R13, the sixteenth resistor R16, the eighteenth resistor R18, the nineteenth resistor R19, and the twentieth resistor R20 are connected in series. The twelfth resistor R12 and the fourteenth resistor R14 are connected with the second node, and the second node is connected with the second pin of the second 8-way encoding switch SW2. The fourteenth resistor R14 and the thirteenth resistor R13 are connected with the tenth node, and the tenth node is connected with the third pin of the second 8-way encoding switch SW2. The thirteenth resistor R13 and the sixteenth resistor R16 are connected with the eleventh node, and the eleventh node is connected with the fourth pin of the second 8-way encoding switch SW2. The sixteenth resistor R16 and the eighteenth resistor R18 are connected with the twelfth node, and the twelfth node is connected with the fifth pin of the second 8-way encoding switch SW2. The eighteenth resistor R18 and the nineteenth resistor R19 are connected with the thirteenth node, and the thirteenth node is connected with the sixth pin of the second 8-way encoding switch SW2. The nineteenth resistor R19 and the twentieth resistor R20 are connected with the fourteenth node, and the fourteenth node is connected with the seventh pin of the second 8-way encoding switch SW2. The eighth resistor R8 and the eighth pin of the first 8-way encoding switch SW1 are connected with the fifteenth node, and the twelfth resistor R12 and the first pin of the second 8-way encoding switch SW2 are connected with the sixteenth node. The tenth resistor R10 is connected with the fifteenth node and the sixteenth node.

2. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 1, characterized in that, The input protection circuit includes a first diode D1 and a first fuse F1. The input end of the first diode D1 is connected with the charging input module. The output end of the first diode D1 is connected with the first fuse F1. The output end of the first diode D1 and the first fuse F1 are further connected with the first node. The first node and the charging input module are further connected with the first capacitor C1.

3. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 2, characterized in that: The first fuse F1 and the charging management chip are further provided with a PWM synchronous step-down current source control circuit, the PWM synchronous step-down current source control circuit comprises a second diode D2, a first MOS tube Q1, a second MOS tube Q2 and a twenty-first resistor R21, the first fuse F1 is connected with the second diode D2 and then connected with the VCC pin of the charging management chip, and the second diode D2 is further connected in parallel with a fifth resistor R5 and a second capacitor C2 at both ends; the second diode D2 is further connected with the source electrode of the first MOS tube Q1, the drain electrode of the first MOS tube Q1 is connected with the drain electrode of the second MOS tube Q2, the source electrode of the second MOS tube Q2 is grounded, the gate electrodes of the first MOS tube Q1 and the second MOS tube Q2 are connected with the charging management chip respectively, a second node is arranged between the drain electrode of the first MOS tube Q1 and the drain electrode of the second MOS tube Q2, the second node is connected with the twenty-first resistor R21 after being connected with the first inductor L1, the both ends of the twenty-first resistor R21 are further connected with the SENCE pin and the BAT pin of the charging management chip respectively, and the twenty-first resistor R21 is further connected with the positive electrode of the nickel-cadmium / nickel-hydrogen battery pack.

4. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 3, characterized in that: The resistance value of the twenty-first resistor R21 is equal to 100 mV / charging current.

5. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 4, characterized in that: An indicating circuit is further arranged between the input protection circuit and the charging management chip, the indicating circuit comprises a ninth resistor R9, an eleventh resistor R11 and a fifteenth resistor R15, the input protection circuit is connected with the ninth resistor R9, the eleventh resistor R11 and the fifteenth resistor R15 respectively, the ninth resistor R9 is connected with the first indicating lamp LED1 and then connected with the FAULT pin of the charging management chip; the eleventh resistor R11 is connected with the second indicating lamp LED2 and then connected with the CHRG pin of the charging management chip; and the fifteenth resistor R15 is connected with the third indicating lamp LED3 and then connected with the READY pin of the charging management chip.

6. A charging circuit for a nickel-cadmium or nickel-metal hydride battery pack according to claim 5, wherein The second 8-way encoding switch SW2 is connected with the positive electrode of the nickel-cadmium / nickel-hydrogen battery pack, the first 8-way encoding switch SW1 and the second 8-way encoding switch SW2 are further connected with a twenty-second resistor R22 respectively, and the twenty-second resistor R22 is further connected between the VCDIV pin and the VCELL pin of the charging management chip.

7. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 6, characterized in that: The resistance value of the twenty-second resistor R22 is equal to the resistance value of the resistance network multiplied by (n-1), wherein n represents the number of battery groups to be charged in the nickel-cadmium / nickel-hydrogen battery pack.

8. A charging circuit for Ni-Cd or Ni-MH battery packs according to claim 7, characterized in that: The nickel-cadmium / nickel-hydrogen battery selection circuit comprises a 1-way encoding switch SW3, and the 1-way encoding switch SW3 is connected with the CHEM pin of the charging management chip.

9. A charging method for the charging circuit for Ni-Cd or Ni-MH battery packs according to any one of claims 5 to 8, characterized in that, The method comprises the following steps: S1, based on the battery chemical type to which the battery group to be charged belongs, operating the 1-way encoding switch SW3 to control the CHEM pin state of the charging management chip, if the battery group to be charged belongs to a nickel-hydrogen battery, grounding the CHEM pin of the charging management chip, and if the battery group to be charged belongs to a nickel-cadmium battery, leaving the CHEM pin of the charging management chip floating; S2, based on the battery stringing number of the battery pack to be charged, adjusting the first 8-way encoding switch SW1 and the second 8-way encoding switch SW2 to the corresponding stringing number gear; S3, connecting the battery pack to be charged into the charging circuit, at this time the third indicator lamp LED3 in the indicating circuit is in the burning state, and the first indicator lamp LED1 and the second indicator lamp LED2 are in the extinguished state; S4, connecting the charging input module to charge, input voltage, at this time the third indicator lamp LED3 and the second indicator lamp LED2 are in the burning state, and the first indicator lamp LED1 is in the extinguished state; waiting for the second indicator lamp LED2 to be extinguished, and the third indicator lamp LED3 to be burning, which indicates that the charging of the battery pack to be charged is completed.

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