A charging method for a lithium battery pack capable of achieving safe charging and the lithium battery pack

Abstract

The present invention discloses a charging method for a lithium battery pack capable of achieving safe charging and a lithium battery pack. In this method, the overcharge detection switching circuit outputs the positive electrode voltage of the first lithium battery in the second lithium battery pack to the charger in the default state. The overcharge detection switching circuit continuously detects whether any lithium battery in the first lithium battery pack is overcharged. When any lithium battery in the first lithium battery pack is overcharged, if the current charger performs overcharge detection on the first lithium battery pack, the overcharge detection switching circuit will then switch and output the voltage representing that any lithium battery in the first lithium battery pack is overcharged to the charger, and the charger stops charging the lithium battery pack to achieve overcharge protection. The advantages are that on the basis of being compatible with the original charger, the switch is only switched when the first lithium battery pack is overcharged, and the switch is not frequently switched, the charging noise is small, the service life is long, and the risk of safety accidents is reduced.

Description

Technical Field

[0001] The present invention relates to a lithium battery pack charging technology, and in particular to a lithium battery pack charging method and a lithium battery pack capable of achieving safe charging. Background Art

[0002] With the rapid development of the lithium battery power supply industry and the expansion of application fields, the safety of lithium battery power supply has also received extensive attention. As Figure 1 shown, the existing lithium battery pack usually includes two lithium battery groups and an overcharge detection and switching circuit. Each lithium battery group includes 5 lithium batteries respectively (two or more lithium batteries connected in parallel are counted as one lithium battery). The positive electrode of the 5th lithium battery is used as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery is used as the negative electrode of the lithium battery group. The overcharge detection and switching circuit consists of two relays. Each relay includes a coil and a double-pole double-throw switch. The double-pole double-throw switch has two common terminals and two groups of switching terminals respectively. Each group of switching terminals consists of two switching terminals. The two common terminals correspond to the two groups of switching terminals one by one. The two common terminals of the double-pole double-throw switch are respectively called the first common terminal and the second common terminal. The two switching terminals of the group of switching terminals corresponding to the first common terminal are respectively called the first switching terminal and the second switching terminal. The two switching terminals of the group of switching terminals corresponding to the second common terminal are respectively called the third switching terminal and the fourth switching terminal. The two lithium battery groups are respectively called the first lithium battery group and the second lithium battery group. The two relays are respectively called the first relay and the second relay. The positive electrode of the 4th lithium battery in the second lithium battery group is connected to the first switching terminal of the double-pole double-throw switch of the first relay K1. The positive electrode of the 3rd lithium battery in the second lithium battery group is connected to the third switching terminal of the double-pole double-throw switch of the first relay K1. The positive electrode of the 2nd lithium battery in the second lithium battery group is connected to the first switching terminal of the double-pole double-throw switch of the second relay K2. The positive electrode of the 1st lithium battery in the second lithium battery group is connected to the third switching terminal of the double-pole double-throw switch of the second relay K2. The positive electrode of the 4th lithium battery in the first lithium battery group is connected to the second switching terminal of the double-pole double-throw switch of the first relay K1. The positive electrode of the 3rd lithium battery in the first lithium battery group is connected to the fourth switching terminal of the double-pole double-throw switch of the first relay K1. The positive electrode of the 2nd lithium battery in the first lithium battery group is connected to the second switching terminal of the double-pole double-throw switch of the second relay K2. The positive electrode of the 1st lithium battery in the first lithium battery group is connected to the fourth switching terminal of the double-pole double-throw switch of the second relay K2. The negative electrode of the 1st lithium battery in the second lithium battery group, one end of the coil of the first relay K1, and one end of the coil of the second relay K2 are connected and then grounded. The negative electrode of the 1st lithium battery in the first lithium battery group is grounded separately. The other end of the coil of the first relay K1 and the other end of the coil of the second relay K2 are connected, and the connection end is used as the overcharge detection control end of the lithium battery pack.

[0003] As shown Figure 2 in the figure, there are nine connection ports on the existing lithium - battery charger for connecting with the lithium - battery pack. After the charger is connected to the lithium - battery pack through these nine connection ports, it collects the voltages of each lithium battery in the lithium - battery pack. The charger stores an over - charge voltage threshold. When the voltage of a certain lithium battery is greater than the over - charge voltage threshold, it indicates that this lithium battery is over - charged, and at this time, the charging of the lithium - battery pack is stopped. These nine connection ports are respectively denoted as C1, C2, C3, C4, ID, B1 +, B2 +, B1 - and B2 -. Among them, C1 is connected to the second common terminal of the double - pole double - throw switch of the second relay in the lithium - battery pack, C2 is connected to the first common terminal of the double - pole double - throw switch of the second relay in the lithium - battery pack, C3 is connected to the second common terminal of the double - pole double - throw switch of the first relay in the lithium - battery pack, C4 is connected to the first common terminal of the double - pole double - throw switch of the first relay in the lithium - battery pack, ID is connected to the over - charge detection control terminal of the lithium - battery pack, B1 + is connected to the positive electrode of the first lithium - battery group of the lithium - battery pack, B2 + is connected to the positive electrode of the second lithium - battery group of the lithium - battery pack, B1 - is connected to the negative electrode of the first lithium - battery group of the lithium - battery pack, and B2 - is connected to the negative electrode of the second lithium - battery group of the lithium - battery pack. When charging the lithium - battery pack, the charger outputs a control signal at ID. This control signal makes the first common terminal and the first switching terminal, and the second common terminal and the third switching terminal of the double - pole double - throw switch in the two relays conduct alternately with the first common terminal and the second switching terminal, and the second common terminal and the fourth switching terminal. When the first common terminal and the first switching terminal, and the second common terminal and the third switching terminal of the double - pole double - throw switch in the two relays conduct, the charger collects the voltages of 5 lithium batteries in the second lithium - battery group in the lithium - battery pack and conducts over - charge detection on the second lithium - battery group. When the first common terminal and the second switching terminal, and the second common terminal and the fourth switching terminal of the double - pole double - throw switch in the two relays conduct, the charger collects the voltages of 5 lithium batteries in the first lithium - battery group in the lithium - battery pack and conducts over - charge detection on the first lithium - battery group.

[0004] The existing charger alternately conducts over - charge detection on the two lithium - battery groups in the lithium - battery pack. Therefore, when the lithium - battery pack is being charged, the double - pole double - throw switches in the two relays in the lithium - battery pack frequently switch along with the alternating detection of the charger. Not only is the charging noise large, but the frequent switching accelerates the wear of the two relays, ultimately resulting in a short service life of the lithium - battery pack and increasing the risk of safety accidents. Summary of the Invention

[0005] One of the technical problems to be solved by the present invention is to provide a lithium - battery pack charging method that can achieve safe charging, does not frequently switch the switch, has less charging noise, and has a longer service life.

[0006] One of the technical solutions adopted by the present invention to solve the above technical problems is as follows: A lithium battery pack charging method capable of achieving safe charging. The lithium battery pack includes two lithium battery groups and an overcharge detection and switching circuit. Each lithium battery group includes 5 series-connected lithium batteries. The positive electrode of the 5th lithium battery serves as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery serves as the negative electrode of the lithium battery group. The two lithium battery groups are respectively called the first lithium battery group and the second lithium battery group. In the default state, the overcharge detection and switching circuit outputs the positive electrode voltage of the 1st lithium battery in the second lithium battery group to the charger. The overcharge detection and switching circuit continuously detects whether any lithium battery in the first lithium battery group is overcharged. When any lithium battery in the first lithium battery group is overcharged, if the current charger is performing overcharge detection on the first lithium battery group, at this time, the overcharge detection and switching circuit will switch, output the voltage representing that any lithium battery in the first lithium battery group is overcharged to the charger, and the charger stops charging the lithium battery pack to achieve overcharge protection.

[0007] Compared with the prior art, the advantages of the lithium battery pack charging method of the present invention are as follows: By enabling the overcharge detection and switching circuit to output the positive electrode voltage of the 1st lithium battery in the second lithium battery group to the charger in the default state, and the overcharge detection and switching circuit continuously detects whether any lithium battery in the first lithium battery group is overcharged. When any lithium battery in the first lithium battery group is overcharged, if the current charger is performing overcharge detection on the first lithium battery group, at this time, the overcharge detection and switching circuit will switch, output the voltage representing that any lithium battery in the first lithium battery group is overcharged to the charger, and the charger stops charging the lithium battery pack to achieve overcharge protection. Thus, when the charger performs overcharge detection on the second lithium battery pack, the positive electrode voltages of each lithium battery in the second lithium battery pack can be directly obtained to determine whether the second lithium battery pack is overcharged. When the charger performs overcharge detection on the first lithium battery pack, if any lithium battery in the first lithium battery pack is not overcharged, the overcharge detection and switching circuit will not switch at this time. Only when any lithium battery in the first lithium battery pack is overcharged, the overcharge detection and switching circuit will switch, output the voltage representing that any lithium battery in the first lithium battery group is overcharged to the charger. On the basis of being compatible with the original charger, the present invention only switches the switch when the first lithium battery group is overcharged, will not perform frequent switch switching, the charging noise can be ignored, the service life of the lithium battery pack is increased, and the risk of safety accidents is reduced.

[0008] The second technical problem to be solved by the present invention is to provide a lithium battery pack that will not perform frequent switch switching, has less charging noise, has a longer service life, and can achieve safe charging.

[0009] The technical solution adopted by the present invention to solve the second of the above technical problems is as follows: A lithium battery pack capable of achieving safe charging, comprising two lithium battery groups and an overcharge detection and switching circuit. Each of the lithium battery groups includes 5 lithium batteries. The positive electrode of the 5th lithium battery serves as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery serves as the negative electrode of the lithium battery group. The two lithium battery groups are respectively referred to as the first lithium battery group and the second lithium battery group. The overcharge detection and switching circuit includes a single-pole double-throw switching circuit, a switching circuit, a voltage conversion circuit, a first signal detection and processing circuit, and a filtering circuit. The voltage conversion circuit is used to convert the positive electrode voltage of the second lithium battery group into a voltage greater than the overcharge voltage threshold of a single lithium battery stored in the charger. The filtering circuit is used to filter and output the positive electrode voltages of the 5 lithium batteries in the first lithium battery group. The first signal detection and processing circuit is used to obtain the positive electrode voltages of the 5 lithium batteries in the first lithium battery group after being filtered by the filtering circuit, and determine whether there is any overcharged lithium battery in the first lithium battery group, and then output an overcharge signal or a non-overcharge signal based on the determination result. The switching circuit is used to access the control signal output by the charger at ID and the signal output by the first signal detection and processing circuit. The switching circuit has a conducting state and a cut-off state. The current state of the switching circuit is determined by the signal output by the first signal detection and processing circuit. The single-pole double-throw switching circuit has a default state and an overcharge state. When the single-pole double-throw switching circuit is in the default state, the single-pole double-throw switching circuit outputs the positive electrode voltage of the 1st lithium battery in the second lithium battery group. When the single-pole double-throw switching circuit is in the overcharge state, the single-pole double-throw switching circuit outputs the voltage converted by the voltage conversion circuit. The initial state of the single-pole double-throw switching circuit is the default state. When the charger outputs a control signal for overcharge detection of the first lithium battery group at ID, if the signal output by the first signal detection and processing circuit is an overcharge signal, at this time the switching circuit is in the conducting state, and the control signal output by the charger controls the single-pole double-throw switching circuit to switch through the switching circuit, so that the single-pole double-throw switching circuit switches from the default state to the overcharge state, and outputs the overcharge voltage output by the voltage conversion circuit. If the signal output by the first signal detection and processing circuit is a non-overcharge signal, at this time the switching circuit is in the cut-off state, and the single-pole double-throw switching circuit remains in the default state unchanged.

[0010] The overcharge detection and switching circuit further includes a second signal detection and processing circuit and an output circuit. The output circuit outputs an output signal of a set magnitude in the initial state. The second signal detection and processing circuit is used to obtain the positive electrode voltages of five lithium batteries in the first lithium battery pack after being filtered by the filtering circuit, and determine whether any lithium battery in the first lithium battery pack is overcharged. When there is no overcharged lithium battery in the first lithium battery pack, the second signal detection and processing circuit outputs a non-overcharge signal. At this time, the output signal of the output circuit remains unchanged at the set magnitude. When there is an overcharged lithium battery in the first lithium battery pack, the second signal detection and processing circuit outputs an overcharge signal. At this time, the magnitude of the output signal of the output circuit changes. The charger can determine whether the first lithium battery pack is overcharged according to the magnitude of the output signal of the output circuit. By adding the second signal detection and processing circuit and the output circuit, this lithium battery pack can set a control signal for controlling the switching of the single-pole double-throw switching circuit and a control signal for obtaining the output signal of the output circuit in the charger. When detecting overcharge of the first lithium battery pack, the charger alternately outputs the two set control signals, and thus alternately realizes overcharge detection and determination through the first signal detection and processing circuit and the second signal detection and processing circuit, meeting the detection standard of the new industry standard IEC 62841-1 for the charging safety of lithium battery packs, that is, the charging is still safe in case of a single failure.

[0011] The voltage conversion circuit includes a first chip of model ME6203, a first capacitor and a second capacitor. The 3rd pin of the first chip is connected to one end of the first capacitor, and the connection end is the input end of the voltage conversion circuit. The input end of the voltage conversion circuit is connected to the positive electrode of the second lithium battery pack. The 1st pin of the first chip is connected to one end of the second capacitor, and the connection end is the output end of the voltage conversion circuit. The output end of the voltage conversion circuit is used to output the converted voltage. The other end of the first capacitor, the other end of the second capacitor and the 2nd pin of the first chip are connected, and the connection end is the grounding end of the voltage conversion circuit. The grounding end of the voltage conversion circuit is connected to the negative electrode of the second lithium battery pack.

[0012] The described single-pole double-throw switching circuit includes a relay and a first diode. The relay includes a coil and a single-pole double-throw switch. The single-pole double-throw switch has a common terminal, a first switching terminal, and a second switching terminal. The first switching terminal of the single-pole double-throw switch is the first input terminal of the single-pole double-throw switching circuit. The first input terminal of the single-pole double-throw switching circuit is connected to the voltage conversion circuit to access the overcharge voltage. The second switching terminal of the single-pole double-throw switch is the second input terminal of the single-pole double-throw switching circuit. The second input terminal of the single-pole double-throw switching circuit is connected to the positive electrode of the first lithium battery in the second lithium battery pack. The common terminal of the single-pole double-throw switch is the output terminal of the single-pole double-throw switching circuit. The output terminal of the single-pole double-throw switching circuit is used to output the overcharge voltage or the positive electrode voltage of the first lithium battery in the second lithium battery pack. One end of the coil is connected to the anode of the first diode, and the connection end is the grounding terminal of the single-pole double-throw switching circuit. The grounding terminal of the single-pole double-throw switching circuit is connected to the negative electrode of the second lithium battery pack. The other end of the coil is connected to the cathode of the first diode, and the connection end is the control terminal of the single-pole double-throw switching circuit. In the initial state, the common terminal of the single-pole double-throw switching circuit is conductively connected to the second switching terminal. When the control signal for overcharge detection of the first lithium battery pack output by the charger at ID is applied to the control terminal of the single-pole double-throw switching circuit, the common terminal of the single-pole double-throw switching circuit switches to be conductively connected to the first switching terminal.

[0013] The described switching circuit includes a first MOS transistor, a first resistor, a second resistor, and a second diode. The drain of the first MOS transistor is the first connection terminal of the switching circuit. The first connection terminal of the switching circuit is connected to the single-pole double-throw switching circuit. The source of the first MOS transistor is connected to one end of the second resistor, and the connection end is the second connection terminal of the switching circuit. The second connection terminal of the switching circuit is used to access the control signal output by the charger at ID. The gate of the first MOS transistor, the other end of the second resistor, and one end of the first resistor are connected. The other end of the first resistor is connected to the anode of the second diode. The cathode of the second diode is the control terminal of the switching circuit. The control terminal of the switching circuit is connected to the first signal detection and processing circuit to access the overcharge signal or non-overcharge signal output by the first signal detection and processing circuit.

[0014] The described first signal detection and processing circuit includes a second chip of model CW1051. The first pin of the second chip is the power supply terminal of the first signal detection and processing circuit, used to connect to the working voltage. The second pin of the second chip is the first input terminal of the first signal detection and processing circuit, used to connect to the positive voltage of the fifth lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The third pin of the second chip is the second input terminal of the first signal detection and processing circuit, used to connect to the positive voltage of the fourth lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The fourth pin of the second chip is the third input terminal of the first signal detection and processing circuit, used to connect to the positive voltage of the third lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The fifth pin of the second chip is the fourth input terminal of the first signal detection and processing circuit, used to connect to the positive voltage of the second lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The sixth pin of the second chip is the fifth input terminal of the first signal detection and processing circuit, used to connect to the positive voltage of the first lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The seventh pin of the second chip is the ground terminal of the first signal detection and processing circuit. The ground terminal of the first signal detection and processing circuit is connected to the negative pole of the first lithium battery pack. The eighth pin of the second chip is the output terminal of the first signal detection and processing circuit. The output terminal of the first signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

[0015] The described filtering circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor. One end of the third resistor is connected to the positive electrode of the first lithium battery pack. The other end of the third resistor is connected to one end of the third capacitor, and the other end of the third capacitor is connected to the negative electrode of the first lithium battery pack. One end of the fourth resistor is connected to the positive electrode of the first lithium battery pack. The other end of the fourth resistor and one end of the fourth capacitor, and their connection end is the first output terminal of the filtering circuit. The first output terminal of the filtering circuit is used to output the positive electrode voltage of the 5th lithium battery of the first lithium battery pack after filtering. One end of the fifth resistor is connected to the positive electrode of the 4th lithium battery of the first lithium battery pack. The other end of the fifth resistor and one end of the fifth capacitor, and their connection end is the second output terminal of the filtering circuit. The second output terminal of the filtering circuit is used to output the positive electrode voltage of the 4th lithium battery of the first lithium battery pack after filtering. One end of the sixth resistor is connected to the positive electrode of the 3rd lithium battery of the first lithium battery pack. The other end of the sixth resistor and one end of the sixth capacitor, and their connection end is the third output terminal of the filtering circuit. The third output terminal of the filtering circuit is used to output the positive electrode voltage of the 3rd lithium battery of the first lithium battery pack after filtering. One end of the seventh resistor is connected to the positive electrode of the 2nd lithium battery of the first lithium battery pack. The other end of the seventh resistor and one end of the seventh capacitor, and their connection end is the fourth output terminal of the filtering circuit. The fourth output terminal of the filtering circuit is used to output the positive electrode voltage of the 2nd lithium battery of the first lithium battery pack after filtering. One end of the eighth resistor is connected to the positive electrode of the 1st lithium battery of the first lithium battery pack. The other end of the eighth resistor and one end of the eighth capacitor, and their connection end is the fifth output terminal of the filtering circuit. The fifth output terminal of the filtering circuit is used to output the positive electrode voltage of the 1st lithium battery of the first lithium battery pack after filtering. The other end of the fourth capacitor is connected to one end of the fifth capacitor. The other end of the fifth capacitor is connected to one end of the sixth capacitor. The other end of the sixth capacitor is connected to one end of the seventh capacitor. The other end of the seventh capacitor is connected to one end of the eighth capacitor. The other end of the eighth capacitor is connected to the negative electrode of the first lithium battery pack.

[0016] The second signal detection and processing circuit described above includes a third chip of model CW1051. The first pin of the third chip is the power supply terminal of the second signal detection and processing circuit, which is used to connect to the working voltage. The second pin of the third chip is the first input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the fifth lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The third pin of the third chip is the second input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the fourth lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The fourth pin of the third chip is the third input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the third lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The fifth pin of the third chip is the fourth input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the second lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The sixth pin of the third chip is the fifth input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the first lithium battery in the first lithium battery pack after being filtered by the filtering circuit. The seventh pin of the third chip is the grounding terminal of the second signal detection and processing circuit. The grounding terminal of the second signal detection and processing circuit is connected to the negative electrode of the first lithium battery pack. The eighth pin of the third chip is the output terminal of the second signal detection and processing circuit. The output terminal of the second signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

[0017] The output circuit described above includes a ninth resistor, a tenth resistor, and a third diode. One end of the ninth resistor and one end of the tenth resistor are connected, and the connection end is the output terminal of the output circuit, which is used to output an output signal. The other end of the tenth resistor is connected to the negative electrode of the second lithium battery pack. The other end of the ninth resistor is connected to the anode of the third diode. The cathode of the third diode is the input terminal of the output circuit, which is used to connect to the overcharge signal or non-overcharge signal output by the second signal detection and processing circuit.

[0018] Compared with the prior art, the advantages of the lithium battery pack of the present invention are that an overcharge detection and switching circuit is constructed by a single-pole double-throw switching circuit, a switching circuit, a voltage conversion circuit, a first signal detection and processing circuit, and a filtering circuit. The voltage conversion circuit converts the positive voltage of the second lithium battery pack into a voltage greater than the overcharge voltage threshold of a single lithium battery stored in the charger. This voltage represents that any one of the lithium batteries in the first lithium battery pack is overcharged. The filtering circuit is used to filter and output the positive voltages of 5 lithium batteries in the first lithium battery pack. The first signal detection and processing circuit is used to obtain the positive voltages of 5 lithium batteries in the first lithium battery pack after being filtered by the filtering circuit, determine whether any one of the lithium batteries in the first lithium battery pack is overcharged, and then output an overcharge signal or a non-overcharge signal based on the determination result. The switching circuit is used to connect the control signal output by the charger at ID and the signal output by the first signal detection and processing circuit. The switching circuit has a conducting state and a cut-off state, and the current state of the switching circuit is determined by the signal output by the first signal detection and processing circuit. The single-pole double-throw switching circuit has a default state and an overcharge state. When the single-pole double-throw switching circuit is in the default state, the single-pole double-throw switching circuit outputs the positive voltage of the first lithium battery in the second lithium battery pack. When the single-pole double-throw switching circuit is in the overcharge state, the single-pole double-throw switching circuit outputs the overcharge voltage output by the voltage conversion circuit. The initial state of the single-pole double-throw switching circuit is the default state. When the charger outputs a control signal for overcharge detection of the first lithium battery pack at ID, if the signal output by the first signal detection and processing circuit is an overcharge signal, the switching circuit is in the conducting state at this time. The control signal output by the charger passes through the switching circuit and then controls the single-pole double-throw switching circuit to switch, so that the single-pole double-throw switching circuit switches from the default state to the overcharge state and outputs the voltage converted by the voltage conversion circuit. At this time, the charger can determine that the first lithium battery pack is overcharged according to the overcharge voltage output by the voltage conversion circuit. If the signal output by the first signal detection and processing circuit is a non-overcharge signal, the switching circuit is in the cut-off state at this time, and the single-pole double-throw switching circuit remains in the default state unchanged. When the charger charges the lithium battery pack of the present invention, C1 is connected to the single-pole double-throw switch, C2 is connected to the positive electrode of the second lithium battery in the second lithium battery pack, C3 is connected to the positive electrode of the third lithium battery in the second lithium battery pack, C4 is connected to the positive electrode of the fourth lithium battery in the second lithium battery pack, ID is connected to the switching circuit, B1+ is connected to the positive electrode of the first lithium battery pack, B2+ is connected to the positive electrode of the second lithium battery pack, B1- is connected to the negative electrode of the first lithium battery pack, and B2- is connected to the negative electrode of the second lithium battery pack. When overcharge detection is performed on the first lithium battery pack, the charger outputs a control signal at ID. If the signal output by the first signal detection and processing circuit is an overcharge signal at this time, the switching circuit is in the conducting state, and the control signal reaches the single-pole double-throw switching circuit through the switching circuit, controlling the single-pole double-throw switching circuit to switch the switch and output the overcharge voltage. Thus, when the charger receives the overcharge voltage, it can determine that the first lithium battery pack is overcharged.Stop charging the lithium battery pack to achieve overcharge protection. If the signal output by the first signal detection and processing circuit is a non-overcharge signal at this time, the switch circuit is in a cut-off state. Even if the charger outputs a control signal at the ID at this time, this control signal cannot reach the single-pole double-throw switching circuit, and the single-pole double-throw switching circuit remains in its original state unchanged. Therefore, the overcharge detection and switching circuit constructed by the single-pole double-throw switching circuit, the switch circuit, the voltage conversion circuit, the first signal detection and processing circuit, and the filtering circuit in the present invention replaces the two relays in the prior art. On the basis of being compatible with the original charger, the switch is only switched when the first lithium battery pack is overcharged, and the switch is not frequently switched, the charging noise can be ignored, the service life of the lithium battery pack is increased, and the risk of safety accidents is reduced. Brief Description of the Drawings

[0019] Figure 1 is the circuit diagram of the existing lithium battery pack;

[0020] Figure 2 is the schematic diagram of the connection port of the existing charger and the lithium battery pack;

[0021] Figure 3 is the structural block diagram of the first embodiment of the lithium battery pack capable of achieving safe charging according to the present invention;

[0022] Figure 4 is the structural block diagram of the second embodiment of the lithium battery pack capable of achieving safe charging according to the present invention;

[0023] Figure 5 is the circuit diagram of the second embodiment of the lithium battery pack capable of achieving safe charging according to the present invention. Detailed Description of the Invention

[0024] The present invention discloses a charging method for a lithium battery pack capable of achieving safe charging. The following further describes in detail the charging method for the lithium battery pack capable of achieving safe charging according to the present invention in conjunction with the embodiments of the drawings.

[0025] Embodiment: A charging method for a lithium battery pack capable of achieving safe charging. The lithium battery pack includes two lithium battery groups and an overcharge detection and switching circuit. Each lithium battery group includes 5 series-connected lithium batteries. The positive electrode of the 5th lithium battery serves as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery serves as the negative electrode of the lithium battery group. The two lithium battery groups are respectively referred to as the first lithium battery group and the second lithium battery group. In the default state, the overcharge detection and switching circuit outputs the positive electrode voltage of the 1st lithium battery in the second lithium battery group to the charger. The overcharge detection and switching circuit continuously detects whether any lithium battery in the first lithium battery group is overcharged. When any lithium battery in the first lithium battery group is overcharged, if the current charger is performing overcharge detection on the first lithium battery group, the overcharge detection and switching circuit will then switch and output the voltage representing that any lithium battery in the first lithium battery group is overcharged to the charger, and the charger stops charging the lithium battery pack to achieve overcharge protection.

[0026] The present invention also discloses a lithium battery pack capable of achieving safe charging. The following further describes in detail the lithium battery pack capable of achieving safe charging according to the present invention in conjunction with the embodiments of the accompanying drawings.

[0027] Embodiment 1: As Figure 3As shown in the figure, a lithium battery pack capable of achieving safe charging includes two lithium battery groups and an overcharge detection and switching circuit. Each lithium battery group includes 5 lithium batteries. The positive electrode of the 5th lithium battery serves as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery serves as the negative electrode of the lithium battery group. The two lithium battery groups are respectively referred to as the first lithium battery group BT1 and the second lithium battery group BT2. The overcharge detection and switching circuit includes a single-pole double-throw switching circuit, a switch circuit, a voltage conversion circuit, a first signal detection and processing circuit, and a filtering circuit. The voltage conversion circuit is used to convert the positive electrode voltage of the second lithium battery group into a voltage greater than the overcharge voltage threshold of a single lithium battery stored in the charger. The filtering circuit is used to filter and output the positive electrode voltages of the 5 lithium batteries in the first lithium battery group BT1. The first signal detection and processing circuit is used to obtain the positive electrode voltages of the 5 lithium batteries in the first lithium battery group after being filtered by the filtering circuit, and determine whether there is an overcharged lithium battery in the first lithium battery group BT1, and then output an overcharge signal or a non-overcharge signal based on the determination result. The switch circuit is used to connect the control signal output by the charger at ID and the signal output by the first signal detection and processing circuit. The switch circuit has a conducting state and a cut-off state. The current state of the switch circuit is determined by the signal output by the current first signal detection and processing circuit. The single-pole double-throw switching circuit has a default state and an overcharge state. When the single-pole double-throw switching circuit is in the default state, the single-pole double-throw switching circuit outputs the positive electrode voltage of the 1st lithium battery in the second lithium battery group BT2. When the single-pole double-throw switching circuit is in the overcharge state, the single-pole double-throw switching circuit outputs the overcharge voltage output by the voltage conversion circuit. The initial state of the single-pole double-throw switching circuit is the default state. When the charger outputs a control signal for overcharge detection of the first lithium battery group BT1 at ID, if the signal output by the first signal detection and processing circuit is an overcharge signal, at this time the switch circuit is in the conducting state, and the control signal output by the charger controls the single-pole double-throw switching circuit to switch through the switch circuit, so that the single-pole double-throw switching circuit switches from the default state to the overcharge state and outputs the voltage converted by the voltage conversion circuit. If the signal output by the first signal detection and processing circuit is a non-overcharge signal, at this time the switch circuit is in the cut-off state, and the single-pole double-throw switching circuit remains in the default state unchanged.

[0028] Embodiment 2: As Figure 4As shown in the figure, the difference between this embodiment and the first embodiment is as follows: In this embodiment, the overcharge detection switching circuit further includes a second signal detection and processing circuit and an output circuit. The output circuit outputs an output signal of a set size in the initial state. The second signal detection and processing circuit is used to obtain the positive voltage of five lithium batteries in the first lithium battery pack BT1 after being filtered by the filter circuit, and determine whether there is an overcharged lithium battery in the first lithium battery pack BT1. When there is no overcharged lithium battery in the first lithium battery pack BT1, the second signal detection and processing circuit outputs a non-overcharge signal, and at this time, the output signal of the output circuit remains unchanged at the set size. When there is an overcharged lithium battery in the first lithium battery pack BT1, the second signal detection and processing circuit outputs an overcharge signal, and at this time, the size of the output signal of the output circuit changes. The charger can determine whether the first lithium battery pack BT1 is overcharged according to the size of the output signal of the output circuit.

[0029] As Figure 5 shown, in this embodiment, the voltage conversion circuit includes a first chip U1 of model ME6203, a first capacitor C1, and a second capacitor C2. The 3rd pin of the first chip U1 is connected to one end of the first capacitor C1, and the connection end is the input end of the voltage conversion circuit. The input end of the voltage conversion circuit is connected to the positive electrode of the second lithium battery pack BT2. The 1st pin of the first chip U1 is connected to one end of the second capacitor C2, and the connection end is the output end of the voltage conversion circuit. The output end of the voltage conversion circuit is used for the converted voltage. The other end of the first capacitor C1, the other end of the second capacitor C2, and the 2nd pin of the first chip U1 are connected, and the connection end is the grounding end of the voltage conversion circuit. The grounding end of the voltage conversion circuit is connected to the negative electrode of the second lithium battery pack BT2. The nominal voltage of each lithium battery in the first lithium battery pack BT1 is generally 3.6V, and the overcharge voltage output by the voltage conversion circuit is 4.4V, which is absolutely greater than the general overcharge voltage of 4.2V for each lithium battery in the first lithium battery pack BT1.

[0030] As Figure 5As shown in the figure, in this embodiment, the single-pole double-throw switching circuit includes a relay K1 and a first diode D1. The relay K1 includes a coil and a single-pole double-throw switch. The single-pole double-throw switch has a common terminal, a first switching terminal, and a second switching terminal. The first switching terminal of the single-pole double-throw switch is the first input terminal of the single-pole double-throw switching circuit. The first input terminal of the single-pole double-throw switching circuit is connected to the voltage conversion circuit to access the overcharge voltage. The second switching terminal of the single-pole double-throw switch is the second input terminal of the single-pole double-throw switching circuit. The second input terminal of the single-pole double-throw switching circuit is connected to the positive electrode of the first lithium battery in the second lithium battery pack BT2. The common terminal of the single-pole double-throw switch is the output terminal of the single-pole double-throw switching circuit. The output terminal of the single-pole double-throw switching circuit is used to output the overcharge voltage or the positive electrode voltage of the first lithium battery in the second lithium battery pack BT2. One end of the coil is connected to the anode of the first diode D1, and the connection end is the grounding terminal of the single-pole double-throw switching circuit. The grounding terminal of the single-pole double-throw switching circuit is connected to the negative electrode of the second lithium battery pack BT2. The other end of the coil is connected to the cathode of the first diode D1, and the connection end is the control terminal of the single-pole double-throw switching circuit. In the initial state, the common terminal of the single-pole double-throw switching circuit is conducting with the second switching terminal. When the control signal for overcharge detection of the first lithium battery pack BT1 output by the charger at ID is applied to the control terminal of the single-pole double-throw switching circuit, the common terminal of the single-pole double-throw switching circuit switches to conduct with the first switching terminal.

[0031] As Figure 5 shown in the figure, in this embodiment, the switching circuit includes a first MOS transistor Q1, a first resistor R1, a second resistor R2, and a second diode D2. The drain of the first MOS transistor Q1 is the first connection terminal of the switching circuit. The first connection terminal of the switching circuit is connected to the single-pole double-throw switching circuit. The source of the first MOS transistor Q1 is connected to one end of the second resistor R2, and the connection end is the second connection terminal of the switching circuit. The second connection terminal of the switching circuit is used to access the control signal output by the charger at ID. The gate of the first MOS transistor Q1, the other end of the second resistor R2, and one end of the first resistor R1 are connected. The other end of the first resistor R1 is connected to the anode of the second diode D2. The cathode of the second diode D2 is the control terminal of the switching circuit. The control terminal of the switching circuit is connected to the first signal detection and processing circuit to access the overcharge signal or non-overcharge signal output by the first signal detection and processing circuit.

[0032] As Figure 5As shown, in this embodiment, the first signal detection and processing circuit includes a second chip U2 of model CW1051. The first pin of the second chip U2 is the power supply terminal of the first signal detection and processing circuit, which is used to connect to the working voltage. The second pin of the second chip U2 is the first input terminal of the first signal detection and processing circuit, which is used to connect to the positive voltage of the fifth lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The third pin of the second chip U2 is the second input terminal of the first signal detection and processing circuit, which is used to connect to the positive voltage of the fourth lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The fourth pin of the second chip U2 is the third input terminal of the first signal detection and processing circuit, which is used to connect to the positive voltage of the third lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The fifth pin of the second chip U2 is the fourth input terminal of the first signal detection and processing circuit, which is used to connect to the positive voltage of the second lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The sixth pin of the second chip U2 is the fifth input terminal of the first signal detection and processing circuit, which is used to connect to the positive voltage of the first lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The seventh pin of the second chip U2 is the ground terminal of the first signal detection and processing circuit. The ground terminal of the first signal detection and processing circuit is connected to the negative electrode of the first lithium battery pack BT1. The eighth pin of the second chip U2 is the output terminal of the first signal detection and processing circuit. The output terminal of the first signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

[0033] As Figure 5As shown, in this embodiment, the filter circuit includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, and an eighth capacitor C8. One end of the third resistor R3 is connected to the positive electrode of the first lithium battery pack BT1, the other end of the third resistor R3 is connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is connected to the negative electrode of the first lithium battery pack BT1. One end of the fourth resistor R4 is connected to the positive electrode of the first lithium battery pack BT1, the other end of the fourth resistor R4 and one end of the fourth capacitor C4 and their connection end is the first output terminal of the filter circuit. The first output terminal of the filter circuit is used to output the positive voltage of the 5th lithium battery of the first lithium battery pack BT1 after filtering. One end of the fifth resistor R5 is connected to the positive electrode of the 4th lithium battery of the first lithium battery pack BT1, the other end of the fifth resistor R5 and one end of the fifth capacitor C5 and their connection end is the second output terminal of the filter circuit. The second output terminal of the filter circuit is used to output the positive voltage of the 4th lithium battery of the first lithium battery pack BT1 after filtering. One end of the sixth resistor R6 is connected to the positive electrode of the 3rd lithium battery of the first lithium battery pack BT1, the other end of the sixth resistor R6 and one end of the sixth capacitor C6 and their connection end is the third output terminal of the filter circuit. The third output terminal of the filter circuit is used to output the positive voltage of the 3rd lithium battery of the first lithium battery pack BT1 after filtering. One end of the seventh resistor R7 is connected to the positive electrode of the 2nd lithium battery of the first lithium battery pack BT1, the other end of the seventh resistor R7 and one end of the seventh capacitor C7 and their connection end is the fourth output terminal of the filter circuit. The fourth output terminal of the filter circuit is used to output the positive voltage of the 2nd lithium battery of the first lithium battery pack BT1 after filtering. One end of the eighth resistor R8 is connected to the positive electrode of the 1st lithium battery of the first lithium battery pack BT1, the other end of the eighth resistor R8 and one end of the eighth capacitor C8 and their connection end is the fifth output terminal of the filter circuit. The fifth output terminal of the filter circuit is used to output the positive voltage of the 1st lithium battery of the first lithium battery pack BT1 after filtering. The other end of the fourth capacitor C4 is connected to one end of the fifth capacitor C5, the other end of the fifth capacitor C5 is connected to one end of the sixth capacitor C6, the other end of the sixth capacitor C6 is connected to one end of the seventh capacitor C7, the other end of the seventh capacitor C7 is connected to one end of the eighth capacitor C8, and the other end of the eighth capacitor C8 is connected to the negative electrode of the first lithium battery pack BT1.

[0034] As Figure 5As shown in the figure, in this embodiment, the second signal detection and processing circuit includes a third chip U3 of model CW1051. The first pin of the third chip U3 is the power supply terminal of the second signal detection and processing circuit, which is used to connect to the working voltage. The second pin of the third chip U3 is the first input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the fifth lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The third pin of the third chip U3 is the second input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the fourth lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The fourth pin of the third chip U3 is the third input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the third lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The fifth pin of the third chip U3 is the fourth input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the second lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The sixth pin of the third chip U3 is the fifth input terminal of the second signal detection and processing circuit, which is used to connect to the positive voltage of the first lithium battery in the first lithium battery pack BT1 after being filtered by the filter circuit. The seventh pin of the third chip U3 is the ground terminal of the second signal detection and processing circuit. The ground terminal of the second signal detection and processing circuit is connected to the negative electrode of the first lithium battery pack BT1. The eighth pin of the third chip U3 is the output terminal of the second signal detection and processing circuit. The output terminal of the second signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

[0035] As Figure 5 shown in the figure, in this embodiment, the output circuit includes a ninth resistor R9, a tenth resistor R10, and a third diode D3. One end of the ninth resistor R9 and one end of the tenth resistor R10 are connected, and the connection end is the output terminal of the output circuit, which is used to output an output signal. The other end of the tenth resistor R10 is connected to the negative electrode of the second lithium battery pack BT2. The other end of the ninth resistor R9 is connected to the anode of the third diode D3. The cathode of the third diode D3 is the input terminal of the output circuit, which is used to connect to the overcharge signal or non-overcharge signal output by the second signal detection and processing circuit.

Claims

1. A lithium battery pack capable of achieving safe charging, comprising two lithium battery groups and an overcharge detection and switching circuit. Each of the lithium battery groups includes 5 series-connected lithium batteries. The positive electrode of the 5th lithium battery serves as the positive electrode of the lithium battery group. The positive electrode of the jth lithium battery is connected to the negative electrode of the (j + 1)th lithium battery, where j = 1, 2, 3, 4. The negative electrode of the 1st lithium battery serves as the negative electrode of the lithium battery group. The two lithium battery groups are respectively referred to as the first lithium battery group and the second lithium battery group, characterized in that The overcharge detection and switching circuit includes a single-pole double-throw switching circuit, a switching circuit, a voltage conversion circuit, a first signal detection and processing circuit, and a filtering circuit. The voltage conversion circuit is used to convert the positive voltage of the second lithium battery pack into a voltage greater than the overcharge voltage threshold of a single lithium battery stored in the charger. The filtering circuit is used to filter and output the positive voltages of the five lithium batteries in the first lithium battery pack. The first signal detection and processing circuit is used to obtain the positive voltages of the five lithium batteries in the first lithium battery pack after being filtered by the filtering circuit, determine whether any lithium battery in the first lithium battery pack is overcharged, and then output an overcharge signal or a non-overcharge signal based on the determination result. The switching circuit is used to connect the control signal output by the charger at ID and the signal output by the first signal detection and processing circuit. The switching circuit has a conducting state and a cutoff state, and the current state of the switching circuit is determined by the signal output by the first signal detection and processing circuit. The single-pole double-throw switching circuit has a default state and an overcharge state. When the single-pole double-throw switching circuit is in the default state, the single-pole double-throw switching circuit outputs the positive voltage of the first lithium battery in the second lithium battery pack. When the single-pole double-throw switching circuit is in the overcharge state, the single-pole double-throw switching circuit outputs the voltage converted by the voltage conversion circuit. The initial state of the single-pole double-throw switching circuit is the default state. When the charger outputs a control signal for overcharge detection of the first lithium battery pack at ID, if the signal output by the first signal detection and processing circuit is an overcharge signal, at this time the switching circuit is in the conducting state, and the control signal output by the charger controls the single-pole double-throw switching circuit to switch through the switching circuit, so that the single-pole double-throw switching circuit switches from the default state to the overcharge state and outputs the voltage converted by the voltage conversion circuit. If the signal output by the first signal detection and processing circuit is a non-overcharge signal, at this time the switching circuit is in the cutoff state, and the single-pole double-throw switching circuit remains in the default state unchanged. The overcharge detection and switching circuit further includes a second signal detection and processing circuit and an output circuit. The filtering circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, and an eighth capacitor.

2. The lithium battery pack capable of achieving safe charging according to claim 1, wherein The output circuit outputs an output signal of a set size in the initial state. The second signal detection and processing circuit is used to obtain the positive electrode voltages of 5 lithium batteries in the first lithium battery pack after being filtered by the filtering circuit, and determine whether any lithium battery in the first lithium battery pack is overcharged. When there is no overcharged lithium battery in the first lithium battery pack, the second signal detection and processing circuit outputs a non-overcharged signal. At this time, the output signal of the output circuit remains unchanged at the set size. When there is any overcharged lithium battery in the first lithium battery pack, the second signal detection and processing circuit outputs an overcharged signal. At this time, the size of the output signal of the output circuit changes. The charger can determine whether the first lithium battery pack is overcharged according to the size of the output signal of the output circuit.

3. The lithium battery pack capable of achieving safe charging according to claim 1 or 2, wherein The voltage conversion circuit includes a first chip of model ME6203, a first capacitor and a second capacitor. The 3rd pin of the first chip is connected to one end of the first capacitor, and the connection end is the input end of the voltage conversion circuit. The input end of the voltage conversion circuit is connected to the positive electrode of the second lithium battery pack. The 1st pin of the first chip is connected to one end of the second capacitor, and the connection end is the output end of the voltage conversion circuit. The output end of the voltage conversion circuit is used to output the converted voltage. The other end of the first capacitor, the other end of the second capacitor and the 2nd pin of the first chip are connected, and the connection end is the grounding end of the voltage conversion circuit. The grounding end of the voltage conversion circuit is connected to the negative electrode of the second lithium battery pack.

4. The lithium battery pack capable of achieving safe charging according to claim 1 or 2, wherein The single-pole double-throw switching circuit includes a relay and a first diode. The relay includes a coil and a single-pole double-throw switch. The single-pole double-throw switch has a common terminal, a first switching terminal and a second switching terminal. The first switching terminal of the single-pole double-throw switch is the first input end of the single-pole double-throw switching circuit. The first input end of the single-pole double-throw switching circuit is connected to the voltage conversion circuit to access the overcharge voltage. The second switching terminal of the single-pole double-throw switch is the second input end of the single-pole double-throw switching circuit. The second input end of the single-pole double-throw switching circuit is connected to the positive electrode of the first lithium battery in the second lithium battery pack. The common terminal of the single-pole double-throw switch is the output end of the single-pole double-throw switching circuit. The output end of the single-pole double-throw switching circuit is used to output the overcharge voltage or the positive electrode voltage of the first lithium battery in the second lithium battery pack. One end of the coil is connected to the anode of the first diode, and the connection end is the grounding end of the single-pole double-throw switching circuit. The grounding end of the single-pole double-throw switching circuit is connected to the negative electrode of the second lithium battery pack. The other end of the coil is connected to the cathode of the first diode, and the connection end is the control end of the single-pole double-throw switching circuit. In the initial state, the common terminal of the single-pole double-throw switching circuit is conducted with the second switching terminal. When the control signal for overcharge detection of the first lithium battery pack output by the charger is connected to the control end of the single-pole double-throw switching circuit, the common terminal of the single-pole double-throw switching circuit switches to be conducted with the first switching terminal.

5. The lithium battery pack capable of achieving safe charging according to claim 1 or 2, characterized in that The switching circuit includes a first MOS transistor, a first resistor, a second resistor, and a second diode. The drain of the first MOS transistor is the first connection terminal of the switching circuit. The first connection terminal of the switching circuit is connected to the single-pole double-throw switching circuit. The source of the first MOS transistor is connected to one end of the second resistor, and the connection terminal is the second connection terminal of the switching circuit. The second connection terminal of the switching circuit is used to access the control signal output by the charger at ID. The gate of the first MOS transistor, the other end of the second resistor, and one end of the first resistor are connected. The other end of the first resistor is connected to the anode of the second diode. The cathode of the second diode is the control terminal of the switching circuit. The control terminal of the switching circuit is connected to the first signal detection and processing circuit to access the overcharge signal or non-overcharge signal output by the first signal detection and processing circuit.

6. The lithium battery pack capable of achieving safe charging according to claim 1 or 2, characterized in that The first signal detection and processing circuit includes a second chip of model CW1051. The first pin of the second chip is the power supply terminal of the first signal detection and processing circuit, which is used to access the working voltage. The second pin of the second chip is the first input terminal of the first signal detection and processing circuit, which is used to access the positive voltage of the fifth lithium battery in the first lithium battery pack filtered by the filter circuit. The third pin of the second chip is the second input terminal of the first signal detection and processing circuit, which is used to access the positive voltage of the fourth lithium battery in the first lithium battery pack filtered by the filter circuit. The fourth pin of the second chip is the third input terminal of the first signal detection and processing circuit, which is used to access the positive voltage of the third lithium battery in the first lithium battery pack filtered by the filter circuit. The fifth pin of the second chip is the fourth input terminal of the first signal detection and processing circuit, which is used to access the positive voltage of the second lithium battery in the first lithium battery pack filtered by the filter circuit. The sixth pin of the second chip is the fifth input terminal of the first signal detection and processing circuit, which is used to access the positive voltage of the first lithium battery in the first lithium battery pack filtered by the filter circuit. The seventh pin of the second chip is the ground terminal of the first signal detection and processing circuit. The ground terminal of the first signal detection and processing circuit is connected to the negative electrode of the first lithium battery pack. The eighth pin of the second chip is the output terminal of the first signal detection and processing circuit. The output terminal of the first signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

7. The lithium battery pack capable of achieving safe charging according to claim 1, wherein One end of the third resistor is connected to the positive electrode of the first lithium battery pack, the other end of the third resistor is connected to one end of the third capacitor, the other end of the third capacitor is connected to the negative electrode of the first lithium battery pack, one end of the fourth resistor is connected to the positive electrode of the first lithium battery pack, the other end of the fourth resistor and one end of the fourth capacitor and their connection end is the first output end of the filtering circuit, and the first output end of the filtering circuit is used to output the positive electrode voltage of the 5th lithium battery of the first lithium battery pack after filtering. One end of the fifth resistor is connected to the positive electrode of the 4th lithium battery of the first lithium battery pack, the other end of the fifth resistor and one end of the fifth capacitor and their connection end is the second output end of the filtering circuit, and the second output end of the filtering circuit is used to output the positive electrode voltage of the 4th lithium battery of the first lithium battery pack after filtering. One end of the sixth resistor is connected to the positive electrode of the 3rd lithium battery of the first lithium battery pack, the other end of the sixth resistor and one end of the sixth capacitor and their connection end is the third output end of the filtering circuit, and the third output end of the filtering circuit is used to output the positive electrode voltage of the 3rd lithium battery of the first lithium battery pack after filtering. One end of the seventh resistor is connected to the positive electrode of the 2nd lithium battery of the first lithium battery pack, the other end of the seventh resistor and one end of the seventh capacitor and their connection end is the fourth output end of the filtering circuit, and the fourth output end of the filtering circuit is used to output the positive electrode voltage of the 2nd lithium battery of the first lithium battery pack after filtering. One end of the eighth resistor is connected to the positive electrode of the 1st lithium battery of the first lithium battery pack, the other end of the eighth resistor and one end of the eighth capacitor and their connection end is the fifth output end of the filtering circuit, and the fifth output end of the filtering circuit is used to output the positive electrode voltage of the 1st lithium battery of the first lithium battery pack after filtering. The other end of the fourth capacitor is connected to one end of the fifth capacitor, the other end of the fifth capacitor is connected to one end of the sixth capacitor, the other end of the sixth capacitor is connected to one end of the seventh capacitor, the other end of the seventh capacitor is connected to one end of the eighth capacitor, and the other end of the eighth capacitor is connected to the negative electrode of the first lithium battery pack.

8. The lithium battery pack capable of achieving safe charging according to claim 2, wherein The second signal detection and processing circuit includes a third chip of model CW1051. The first pin of the third chip is the power supply terminal of the second signal detection and processing circuit for accessing the operating voltage. The second pin of the third chip is the first input terminal of the second signal detection and processing circuit for accessing the positive voltage of the fifth lithium battery in the first lithium battery pack after being filtered by the filter circuit. The third pin of the third chip is the second input terminal of the second signal detection and processing circuit for accessing the positive voltage of the fourth lithium battery in the first lithium battery pack after being filtered by the filter circuit. The fourth pin of the third chip is the third input terminal of the second signal detection and processing circuit for accessing the positive voltage of the third lithium battery in the first lithium battery pack after being filtered by the filter circuit. The fifth pin of the third chip is the fourth input terminal of the second signal detection and processing circuit for accessing the positive voltage of the second lithium battery in the first lithium battery pack after being filtered by the filter circuit. The sixth pin of the third chip is the fifth input terminal of the second signal detection and processing circuit for accessing the positive voltage of the first lithium battery in the first lithium battery pack after being filtered by the filter circuit. The seventh pin of the third chip is the ground terminal of the second signal detection and processing circuit, and the ground terminal of the second signal detection and processing circuit is connected to the negative electrode of the first lithium battery pack. The eighth pin of the third chip is the output terminal of the second signal detection and processing circuit, and the output terminal of the second signal detection and processing circuit is used to output an overcharge signal or a non-overcharge signal.

9. The lithium battery pack capable of achieving safe charging according to claim 2, wherein The output circuit includes a ninth resistor, a tenth resistor, and a third diode. One end of the ninth resistor and one end of the tenth resistor are connected, and the connection end is the output terminal of the output circuit for outputting an output signal. The other end of the tenth resistor is connected to the negative electrode of the second lithium battery pack. The other end of the ninth resistor is connected to the anode of the third diode, and the cathode of the third diode is the input terminal of the output circuit for accessing the overcharge signal or non-overcharge signal output by the second signal detection and processing circuit.

10. The method for charging a lithium battery pack capable of achieving safe charging according to claim 1, characterized in that In the default state, the overcharge detection switching circuit outputs the positive voltage of the first lithium battery in the second lithium battery pack to the charger. The overcharge detection switching circuit continuously detects whether any lithium battery in the first lithium battery pack is overcharged. When any lithium battery in the first lithium battery pack is overcharged, if the current charger performs overcharge detection on the first lithium battery pack, at this time the overcharge detection switching circuit will switch and output the voltage representing that any lithium battery in the first lithium battery pack is overcharged to the charger, and the charger stops charging the lithium battery pack to achieve overcharge protection.

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