Lithium ion battery pack and charging system

Abstract

A lithium ion battery pack (10) comprises: a lithium ion battery cell (20); a housing in which the lithium ion battery cell (20) is built and which is provided with a positive electrode terminal (Pvcc+), a negative electrode terminal (Pvcc-), and communication terminals (Pcl+, Pcl-); a BMS circuit (110) which is built in the housing and which includes a control unit that controls charging and discharging of the lithium ion battery cell (20); a communication IC (40) which causes terminal voltage values of the lithium ion battery cell (20) to output to the outside through the communication terminals (Pcl+, Pcl-) without passing through the BMS circuit (110); a first relay circuit (61) which, upon receiving a first control signal from the control unit of the BMS circuit (110), conducts or cuts off power supply to the lithium ion battery cell (20) through the positive electrode terminal (Pvcc+) and the negative electrode terminal (Pvcc-); an LDO (51) which supplies power to the control unit; and an LDO(52) which supplies power to the communication IC (40) separately from the LDO (51).

Description

Lithium-ion battery pack and charging system

[0001] The present invention relates to a lithium-ion battery pack including lithium-ion battery cells and a control circuit that charges and discharges the lithium-ion battery cells.

[0002] Patent Document 1 describes a battery pack and a diagnostic device for the battery pack, and describes a technique for determining the deterioration state of the battery.

[0003] The battery pack includes battery cells, a BMS circuit, and a communication interface. The communication interface connects the BMS circuit to an external device such as a diagnostic device. The diagnostic device diagnoses the condition of the battery pack through the BMS circuit.

[0004] JP 2011-133443 A

[0005] However, with the technology of Patent Document 1, even if the BMS circuit is faulty and the battery cells are not faulty and are in a normal state, it is not possible to determine that only the BMS circuit is faulty. As a result, it takes time and effort to identify the specific cause of the battery pack failure.

[0006] Therefore, an object of the present invention is to provide a technology that enables control of charging and discharging of lithium-ion battery cells from an external device even when only the BMS circuit has failed, and enables the degree of deterioration of the lithium-ion battery cells to be analyzed, thereby making it possible to reliably determine whether the failure is due to circuit factors or battery cell degradation.

[0007] The lithium-ion battery pack of the present invention includes a lithium-ion battery cell, a housing that houses the lithium-ion battery cell and has a positive terminal, a negative terminal, and a communication terminal, a BMS circuit that is housed in the housing and includes a control unit that controls charging and discharging of the lithium-ion battery cell, a communication control unit that outputs the terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without going through the BMS circuit, a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal, a first regulator that supplies power to the control unit, and a second regulator that supplies power to the communication control unit separately from the first regulator.

[0008] With this configuration, even if the BMS circuit fails, the terminal voltage of the lithium-ion battery cell can be output to the outside, making it possible to determine whether the failure is in the BMS circuit or something else.

[0009] The lithium-ion battery pack of the present invention includes a lithium-ion battery cell, a housing that houses the lithium-ion battery cell and has a positive terminal, a negative terminal, a communication terminal, and a control terminal, a BMS circuit that is housed in the housing and includes a control unit that controls charging and discharging of the lithium-ion battery cell, a communication control unit that outputs the terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without going through the BMS circuit, a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the supply of power to the lithium-ion battery cell through the positive terminal and the negative terminal, and a second relay circuit that is connected in parallel to the first relay circuit and receives a second control signal from the control terminal and conducts or cuts off the supply of power to the lithium-ion battery cell through the positive terminal and the negative terminal.

[0010] With this configuration, even if the first relay circuit, which normally performs conduction / cutoff operation, fails, the second relay circuit can be externally controlled to conduct / cut off. Furthermore, the terminal voltage of the lithium-ion battery cell can be output externally without using a BMS circuit. This makes it possible to control charging and discharging of the lithium-ion battery cell from an external device, even if the first relay circuit fails, and allows the degradation of the lithium-ion battery cell to be analyzed.

[0011] The charging system of the present invention includes a lithium-ion battery pack and a charger connectable to the lithium-ion battery pack and having a function of obtaining the OCV of the lithium-ion battery cells.

[0012] The lithium-ion battery pack includes a lithium-ion battery cell, a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, a communication terminal, and a control terminal, a BMS circuit built into the housing and including a control unit that controls charging and discharging of the lithium-ion battery cell, a communication control unit that outputs the terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without passing through the BMS circuit, a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the supply of power to the lithium-ion battery cell through the positive terminal and the negative terminal, and a second relay circuit that is connected in parallel to the first relay circuit and receives a second control signal from the control terminal and conducts or cuts off the supply of power to the lithium-ion battery cell through the positive terminal and the negative terminal.

[0013] When the lithium-ion battery pack cannot be charged, the charger operates in a first mode in which the second relay circuit is turned on through the control terminal based on the terminal voltage value of the lithium-ion battery cell output from the communication control unit, charging at a predetermined current value for a first time, and measuring the terminal voltage value of the lithium-ion battery cell immediately after the first time has elapsed; and after the first charging mode ends, the charger operates in a second mode in which the second relay circuit is turned off, charging is paused for a second time, the OCV value of the lithium-ion battery cell immediately after the second time has elapsed, and then the charger returns to the first mode, and estimates the cause of failure of the lithium-ion battery pack based on the acquired OCV data.

[0014] With this configuration, if the lithium-ion battery pack cannot be charged or discharged for an unknown reason, by connecting a dedicated charger, it becomes possible to charge and discharge the battery even if the control unit or the first relay circuit is broken, and it can be determined whether the problem is with the BMS board (for example, a failure due to circuitry) or something else (for example, a failure due to deterioration of the battery cells).

[0015] According to this invention, even if only the BMS circuit has failed, it is possible to control charging and discharging of the lithium-ion battery cell from an external device and to analyze the degree of deterioration of the lithium-ion battery cell, thereby making it possible to more reliably determine whether the failure is due to circuit factors or battery cell degradation.

[0016] FIG. 1 is a circuit diagram of a lithium-ion battery pack according to a first embodiment of the present invention. FIG. 2 is a flowchart showing an example of failure analysis of the lithium-ion battery pack according to the first embodiment of the present invention. FIG. 3 is a circuit diagram of a lithium-ion battery pack according to a second embodiment of the present invention. FIG. 4 is a flowchart showing an example of failure analysis of the lithium-ion battery pack according to the second embodiment of the present invention. FIG. 5 is an external perspective view showing an example of the configuration of a lithium-ion battery pack 10A according to the second embodiment of the present invention. FIG. 6(A) is an external perspective view of a charger with analysis function according to the second embodiment of the present invention, and FIG. 6(B) is an external perspective view showing the lithium-ion battery pack connected (mounted) to the charger with analysis function. FIG. 7 is a circuit diagram of a lithium-ion battery pack according to a third embodiment of the present invention.

[0017] [First embodiment] A lithium ion battery pack according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a circuit diagram of the lithium ion battery pack according to the first embodiment of the present invention.

[0018] As shown in FIG. 1, the lithium-ion battery pack 10 includes a lithium-ion battery cell 20, an MPU 31, a protection IC 32, an operational amplifier (OP-AMP) 33, a communication IC 40, LDOs 51 and 52, a first relay circuit 61, a fuse 70, and a measurement resistor 200.

[0019] The BMS circuit 110 is configured by the MPU 31, the protection IC 32, the operational amplifier 33 (OP-AMP), the LDOs 51 and 52, the first relay circuit 61, and the fuse 70.

[0020] The MPU 31 and the protection IC 32 constitute a "controller" of the BMS circuit 110. The communication IC 40 corresponds to a "communication controller", the LDO 51 corresponds to a "first regulator", and the LDO 52 corresponds to a "second regulator".

[0021] The lithium-ion battery pack 10 includes a positive terminal Pvcc+, a negative terminal Pvcc-, and communication terminals Pcl+ and Pcl-.

[0022] A first relay circuit 61 is connected to the positive terminal Pvcc+. The positive electrode of the lithium ion battery cell 20 is connected to the first relay circuit 61 through a fuse 70. The negative electrode of the lithium ion battery cell 20 is connected to the negative terminal Pvcc- through a measuring resistor 200.

[0023] The lithium ion battery cell 20 is made up of, for example, a plurality of individual lithium ion batteries connected in series.

[0024] The input terminal of the LDO 51 is connected to the node between the fuse 70 and the positive electrode of the lithium-ion battery cell 20. The output terminal of the LDO 51 is connected to the MPU 31 and the protection IC 32.

[0025] The input terminal of the LDO 52 is connected to the node between the fuse 70 and the positive electrode of the lithium-ion battery cell 20. The output terminal of the LDO 52 is connected to the communication IC 40.

[0026] The MPU 31 is connected to the protection IC 32 , the first relay circuit 61 , the operational amplifier 33 , and the communication IC 40 .

[0027] The protection IC 32 is connected to the lithium ion battery cell 20. More specifically, the protection IC 32 is connected to each of a plurality of nodes where a plurality of individual lithium ions are connected in series in sequence. The protection IC 32 is also connected to the negative terminal Pvcc-.

[0028] The operational amplifier 33 is connected to both ends of the measurement resistor 200 .

[0029] The communication IC 40 is connected to the lithium ion battery cell 20. More specifically, the protection IC 32 is connected to each of a plurality of nodes where a plurality of individual lithium ion cells are connected in series in sequence. The communication IC 40 is also connected to the negative terminal Pvcc-.

[0030] The communication IC 40 is connected to the communication terminals Pcl+ and Pcl-.

[0031] The first relay circuit 61 includes a series circuit of a switching element Q1 and a switching element Q2. The switching elements Q1 and Q2 are, for example, n-channel MOSFETs. The series circuit of the switching elements Q1 and Q2 is connected between the positive terminal Pvcc+ and a fuse 70.

[0032] More specifically, the source terminal of the switching element Q1 is connected to the source terminal of the switching element Q2. The drain terminal of the switching element Q1 is connected to the fuse 70. The drain terminal of the switching element Q2 is connected to the positive terminal Pvcc+.

[0033] The gate terminal of the switching element Q1 and the gate terminal of the switching element Q2 are connected to the MPU 31.

[0034] The MPU 31 and the protection IC 32 are supplied with power through the LDO 51. The MPU 31 and the protection IC 32 are driven by the power supply and control the charging and discharging of the lithium ion battery cells 20.

[0035] The MPU 31 outputs a first control signal for charging and discharging to the first relay circuit 61. The first control signal is a signal that connects or disconnects the drain terminals and source terminals of the switching elements Q1 and Q2 in order to connect or cut off the power supply to the lithium-ion battery cell 20.

[0036] The protection IC 32 protects the lithium ion battery cell 20 from overcharging and overdischarging during charging and discharging based on the potential difference between multiple nodes of the lithium ion battery cell 20.

[0037] The operational amplifier 33 detects the voltage across the measuring resistor 200 and outputs it to the MPU 31. The MPU 31 controls the power supply to the lithium ion battery cell 20 based on the detected voltage across the resistor 200.

[0038] When the lithium-ion battery pack 10 is operating normally, the communication IC 40 controls communication between the MPU 31 and an external charger or the like via the communication terminals Pcl+ and Pcl-.

[0039] Furthermore, the communication IC 40 detects the potential differences between the multiple nodes of the lithium-ion battery cell 20, i.e., the voltages across the multiple individual lithium-ion batteries that make up the lithium-ion battery cell 20. The communication IC 40 can output the detected voltages across the multiple individual lithium-ion batteries to an external charger or analyzer via communication terminals Pcl+ and Pcl-.

[0040] (Operation in the Event of a Failure of the BMS Circuit 110) In the conventional configuration, the communication IC is provided in the BMS circuit. Therefore, if the BMS circuit fails, an external charger with analysis function or an analysis device cannot acquire the voltages across the multiple individual lithium-ion batteries that make up the lithium-ion battery cell 20. Therefore, in the past, if a lithium-ion battery pack fails, it was not possible to determine whether the failure was in the BMS circuit or in the lithium-ion battery cell 20.

[0041] However, in the lithium-ion battery pack 10 configured as described above, the communication IC 40 is not provided in the BMS circuit 110. Furthermore, the communication IC 40 can detect the voltages across the multiple individual lithium-ion batteries that make up the lithium-ion battery cell 20, and output the voltages to the outside via the communication terminals Pcl+ and Pcl-.

[0042] As a result, if an external charger or analysis device with analysis function cannot communicate with the MPU 31 and can obtain the voltages across the multiple individual lithium-ion batteries that make up the lithium-ion battery cell 20, it can determine that the BMS circuit 110 is faulty.

[0043] Furthermore, in the lithium-ion battery pack 10, power is supplied to the MPU 31 and the protection IC 32 by the LDO 51, and power is supplied to the communication IC 40 by the LDO 52. That is, power is supplied to the communication IC 40 via a power supply path different from that for the MPU 31 and the protection IC 32. Therefore, in the event of a failure in the BMS circuit 110, the voltages across the multiple individual lithium-ion batteries that make up the lithium-ion battery cell 20 can be more reliably obtained and output to the outside.

[0044] (Example of Fault Determination) Fig. 2 is a flowchart showing an example of fault analysis of the lithium-ion battery pack according to the first embodiment of the present invention. As shown in Fig. 2, when an error is displayed in the lithium-ion battery pack 10 (S1: YES), the cell voltage of the lithium-ion battery cell 20 is acquired via the communication IC 40 (S2).

[0045] If the cell voltage can be acquired (S3: YES), it is determined that there is a failure in the BMS circuit 110 (S4). If the cell voltage cannot be acquired (S3: NO), it is determined that there is some other failure, including a failure in the lithium-ion battery cell 20, excluding a single failure in the BMS circuit 110 (S5).

[0046] As a result, by using the lithium-ion battery pack of this embodiment, even if only the BMS circuit 110 is faulty, it is possible to control charging and discharging of the lithium-ion battery cells 20 from an external device, and to analyze the degree of deterioration of the lithium-ion battery cells 20, thereby more reliably determining whether the failure is due to a circuit factor (e.g., the BMS circuit 110) or a factor such as deterioration of the lithium-ion battery cells 20. If there is an "abnormality in the lithium-ion battery cells 20," the problem can be sent to the battery manufacturer, but if there is an "abnormality in the BMS circuit 110," it can be handled at the device manufacturer's support center. This can shorten the repair time and improve user convenience.

[0047] Second Embodiment A lithium ion battery pack according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 3 is a circuit diagram of the lithium ion battery pack according to the second embodiment of the present invention.

[0048] 3, the lithium-ion battery pack 10A according to the second embodiment differs from the lithium-ion battery pack 10 according to the first embodiment in that it includes a BMS circuit 110A. Other configurations of the lithium-ion battery pack 10A are the same as those of the lithium-ion battery pack 10, and descriptions of similar parts will be omitted.

[0049] The BMS circuit 110A differs from the BMS circuit 110 according to the first embodiment in the following configuration: The other configurations of the BMS circuit 110A are similar to those of the BMS circuit 110, and a description of similar parts will be omitted.

[0050] The BMS circuit 110A includes a second relay circuit 62, a charge control terminal Pch, and a discharge control terminal Pds. The charge control terminal Pch and the discharge control terminal Pds constitute a "control terminal."

[0051] The second relay circuit 62 is connected in parallel to the first relay circuit 61. The second relay circuit 62 includes a series circuit of a switching element Q3 and a switching element Q4. The switching elements Q3 and Q4 are, for example, n-channel MOSFETs. The series circuit of the switching elements Q3 and Q4 is connected between the positive terminal Pvcc+ and a fuse 70.

[0052] More specifically, the source terminal of the switching element Q3 is connected to the source terminal of the switching element Q4. The drain terminal of the switching element Q3 is connected to the fuse 70. The drain terminal of the switching element Q4 is connected to the positive terminal Pvcc+.

[0053] The gate terminal (first control terminal) of switching element Q3 is connected to discharge control terminal Pds. The gate terminal (second control terminal) of switching element Q4 is connected to charge control terminal Pch. A discharge control signal is input from the outside to discharge control terminal Pds, and a charge control signal is input from the outside to charge control terminal Pch. This pair of discharge control signal and charge control signal corresponds to a "second control signal."

[0054] With this configuration, the lithium-ion battery pack 10A can control charging of the lithium-ion battery cells 20 by a charge control signal input from outside the lithium-ion battery pack 10A through the charge control terminal Pch. Also, the lithium-ion battery pack 10A can control discharging of the lithium-ion battery cells 20 by a discharge control signal input from outside the lithium-ion battery pack 10A through the discharge control terminal Pds.

[0055] As a result, even if the first relay circuit 61 is in an interrupted state due to a malfunction of the MPU 31 or the like, charging and discharging control of the lithium ion battery cell 20 can be realized through the second relay circuit 62 by an external control signal.

[0056] The lithium-ion battery pack 10A also includes an LDO regulator 50. The LDO regulator 50 is connected to the MPU 31, the protection IC 32, and the communication IC 40. Power is supplied to the MPU 31, the protection IC 32, and the communication IC 40 through the LDO regulator 50. This configuration allows the lithium-ion battery pack 10A to have a smaller number of LDO regulators than the lithium-ion battery pack 10 according to the first embodiment. This allows the lithium-ion battery pack 10A to have a simpler configuration.

[0057] 4 is a flowchart showing an example of failure analysis of a lithium-ion battery pack according to a second embodiment of the present invention. Note that the following description will be given of a case where a charger with an analysis function is used for failure analysis.

[0058] As shown in FIG. 4, if an error is displayed on the lithium ion battery pack 10A (S1: YES), the lithium ion battery pack 10A is connected to a charger with an analysis function (S21).

[0059] The charger with analysis function acquires the cell voltage of the lithium ion battery cell 20 through the communication IC 40 (S2).

[0060] If the cell voltage can be acquired (S3: YES), the charger with analysis function compares the cell voltage Vp with a threshold value THv. The threshold value THv is set based on the lower limit of the remaining capacity of the lithium-ion battery cell 20.

[0061] If the cell voltage Vp is lower than the threshold value THv (S22: YES), the charger with analysis function supplies a control signal for analysis (a second control signal (a control signal given to the second relay circuit 62)) through the charge control terminal Pch and the discharge control terminal Pds (S23).

[0062] If the cell voltage Vp is equal to or greater than the threshold value THv (S22: NO), the analysis function-equipped charger sets itself as a load (S24), and then supplies a control signal for analysis (second control signal) through the charge control terminal Pch and the discharge control terminal Pds (S23).

[0063] The charger with analysis function acquires OCV data for the lithium-ion battery pack 10A (S25). To acquire the OCV data, for example, a first mode is executed in which the second relay circuit 62 is turned on by supplying a charge control signal, charging is performed at 1 C for one minute (first time), and the terminal voltage value (voltage across both ends) of the lithium-ion battery cell 20 is measured immediately after the first time has elapsed. To acquire the OCV data, after the first mode is completed, the second relay circuit 62 is interrupted by a discharge control signal, charging is paused for, for example, 10 minutes (second time), the terminal voltage value (voltage across both ends) of the lithium-ion battery cell 20 is measured immediately after the second time has elapsed, and then the second mode is executed in which the charger returns to the first mode. The OCV data is acquired by repeatedly switching between the first mode and the second mode.

[0064] The charger with analysis function acquires a continuous OCV curve by repeating the first mode and the second mode. The charger with analysis function has a calculation function that analyzes how the acquired continuous OCV curve changes and diagnoses its degree of deterioration. The way the OCV curve changes corresponds to changes in the oxidation-reduction potential of the positive electrode material and the negative electrode material, and the charger with analysis function can capture changes in each material through analysis and diagnose them as the degree of deterioration.

[0065] If the deterioration level of the lithium-ion battery cells 20 of the lithium-ion battery pack 10A is not serious (S26: NO), the charger with analysis function determines that there is a failure in the BMS circuit 110 (S4).If the deterioration level of the lithium-ion battery cells 20 of the lithium-ion battery pack 10A is serious (S26: YES), the charger with analysis function determines that there is some other failure, including deterioration of the lithium-ion battery cells 20, excluding an isolated failure of the BMS circuit 110 (S5).

[0066] The charger with analysis function may also perform the degradation analysis, or the charger with analysis function may acquire the OCV value and transmit it to an external server via a communication line, and the external server may then analyze the degradation. In this case, the external server may transmit the degradation analysis results to the charger with analysis function via the communication line.

[0067] In this way, the charging system including the lithium-ion battery pack 10A and the charger with analysis function can analyze the degree of deterioration of the lithium-ion battery cells 20 and determine whether there is a fault in the BMS circuit 110A. This allows the charging system to estimate the cause of the fault in the lithium-ion battery pack 10A in more detail, improving the accuracy of the fault determination in the BMS circuit 110A.

[0068] (Structure of Lithium-ion Battery Pack 10A and Charger with Analysis Function 90) FIG. 5 is an external perspective view showing an example of the configuration of a lithium-ion battery pack 10A according to a second embodiment of the present invention.

[0069] 5, the lithium-ion battery pack 10A includes a housing 100. The housing 100 houses the lithium-ion battery cell 20, a BMS circuit 110A, a communication IC 40, and a measuring resistor 200.

[0070] A positive terminal Pvcc+, a negative terminal Pvcc-, communication terminals Pcl+ and Pcl-, a charge control terminal Pch, and a discharge control terminal Pds are formed on one side of the housing 100. These terminals allow the lithium-ion battery pack 10A to be electrically connected to an external charger, a charger with an analysis function, an analyzer, or the like.

[0071] FIG. 6(A) is an external perspective view of a charger with an analysis function according to a second embodiment of the present invention, and FIG. 6(B) is an external perspective view showing a state in which a lithium-ion battery pack is connected (attached) to the charger with an analysis function.

[0072] 6(A) and 6(B), the charger with analysis function 90 has a recess 91 for mounting the lithium-ion battery pack 10A. The charger with analysis function 90 also has a display unit 92, a plurality of operation buttons 93, and a power cable 94.

[0073] The display unit 92 displays, for example, the calculation result of the deterioration level. This allows the operator of the charger with analysis function 90 to easily check the calculation result of the deterioration level. The multiple operation buttons 93 accept operation input for analysis. For example, the charger with analysis function 90 performs analysis in response to this operation input.

[0074] On the side wall of the recess 91, a positive terminal Pvcc+, a negative terminal Pvcc-, communication terminals Pcl+ and Pcl-, a charge control terminal Pch, and a discharge control terminal Pds are formed.

[0075] The lithium-ion battery pack 10A is mounted in the recess 91 so that one side of the housing 100 on which the above-mentioned terminals are formed abuts against the side wall on which the terminals of the charger with analysis function 90 are formed. This electrically connects the terminals of the lithium-ion battery pack 10A to the terminals of the charger with analysis function 90.

[0076] In this case, it is preferable that the lithium-ion battery pack 10A be provided with a cover member that covers the charge control terminal Pch and the discharge control terminal Pds when the lithium-ion battery pack 10A is not attached to the charger 90 with analysis function and locks this state.

[0077] In this case, the side wall of the recess 91 of the charger 90 with analysis function is provided with a mechanism that unlocks the cover member when the lithium-ion battery pack 10A is attached to the recess 91, exposing the charge control terminal Pch and discharge control terminal Pds of the lithium-ion battery pack 10A.

[0078] As a result, the charge control terminal Pch and the discharge control terminal Pds, which are necessary only for analysis, are hidden during normal use of the lithium-ion battery pack 10A. This prevents unwanted signal input to the charge control terminal Pch and the discharge control terminal Pds during normal use of the lithium-ion battery pack 10A. Furthermore, the charger during normal use does not have the charge control terminal Pch and the discharge control terminal Pds. Therefore, erroneous supply of charge control signals and discharge control signals to the lithium-ion battery pack 10A by the charger during normal use does not occur.

[0079] On the other hand, during analysis, the charge control terminal Pch and discharge control terminal Pds of the lithium ion battery pack 10A can be connected to the charge control terminal Pch and discharge control terminal Pds of the charger 90 with analysis function.

[0080] [Third Embodiment] A lithium ion battery pack according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 7 is a circuit diagram of the lithium ion battery pack according to the third embodiment of the present invention.

[0081] 7, the lithium-ion battery pack 10B according to the third embodiment differs from the lithium-ion battery pack 10A according to the second embodiment in that it includes a BMS circuit 110B. The other configuration of the lithium-ion battery pack 10B is the same as that of the lithium-ion battery pack 10A, and a description of the same parts will be omitted.

[0082] The BMS circuit 110B includes an LDO 51 and an LDO 52. The LDO 51 is connected to the MPU 31 and the protection IC 32. The LDO 52 is connected to the communication IC 40.

[0083] With this configuration, power is supplied to the communication IC 40 and power is supplied to the MPU 31 and protection IC 32 by individual LDOs.

[0084] This ensures that power will continue to be supplied to the communication IC 40 even if the LDO 51 supplying power to the MPU 31 fails and the MPU 31 is shut down. Therefore, when the lithium-ion battery pack 10B is connected to an analysis device such as a charger 90 with an analysis function, the lithium-ion battery pack 10B can transmit the cell voltage value of the lithium-ion battery cell 20 to the analysis device.

[0085] <1> A lithium-ion battery pack comprising: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, and a communication terminal; a BMS circuit built into the housing and including a control unit that controls charging and discharging of the lithium-ion battery cell; a communication control unit that outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without going through the BMS circuit; a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; a first regulator that supplies power to the control unit; and a second regulator that is separate from the first regulator and supplies power to the communication control unit.

[0086] <2> A lithium-ion battery pack comprising: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, a communication terminal, and a control terminal; a BMS circuit built into the housing and including a control unit that controls charging and discharging of the lithium-ion battery cell; a communication control unit that outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without going through the BMS circuit; a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; and a second relay circuit that is connected in parallel to the first relay circuit and receives a second control signal from the control terminal and conducts or cuts off power supply to the lithium-ion battery cell through the positive terminal and the negative terminal.

[0087] <3> The lithium-ion battery pack according to <2>, wherein the second relay circuit is formed by a series circuit in which drain terminals or source terminals of two n-channel MOSFETs are connected to each other, and gate terminals of each n-channel MOSFET are used as a first control terminal and a second control terminal.

[0088] <4> A charging system comprising: a lithium-ion battery pack; and a charger connectable to the lithium-ion battery pack and having a function of acquiring an OCV of a lithium-ion battery cell, wherein the lithium-ion battery pack comprises: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, a communication terminal, and a control terminal; a BMS circuit built into the housing and including a control unit that controls charging and discharging of the lithium-ion battery cell; a communication control unit that outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without passing through the BMS circuit; a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; and a second relay circuit connected in parallel to the first relay circuit and that receives a second control signal from the control terminal and conducts or cuts off power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; a first mode in which the second relay circuit is turned on through the control terminal based on the terminal voltage value of the lithium-ion battery cell output from the communication control unit, charging is performed at a predetermined current value for a first time period, and the terminal voltage value of the lithium-ion battery cell immediately after the first time period has elapsed; and a second mode in which, after the first mode has ended, the second relay circuit is turned off, charging is paused for a second time period, the OCV value of the lithium-ion battery cell immediately after the second time period has elapsed, and then the charging system returns to the first mode; and a charging system in which the cause of a failure of the lithium-ion battery pack is estimated based on the acquired OCV data.

[0089] <5> The charging system of <4>, comprising: an external server having a calculation function for analyzing OCV data of the lithium-ion battery cell; and a communication line connecting the external server and the charger, wherein the charger transmits the acquired plurality of OCV data to the external server through the communication line, the external server calculates a degree of deterioration of the lithium-ion battery cell using the calculation function, and then transmits the result to the charger through the communication line, and the charger displays the calculation result of the degree of deterioration.

[0090] 10, 10A, 10B: Lithium-ion battery pack 20: Lithium-ion battery cell 31: MPU 32: Protection IC 33: Operational amplifier 40: Communication IC 50, 51, 52: LDO 61: First relay circuit 62: Second relay circuit 70: Fuse 90: Charger 91: Recess 92: Display 93: Operation button 94: Power cable 100: Housing 110, 110A, 110B: BMS circuit 200: Measurement resistor Q1, Q2, Q3, Q4: Switching element Pch: Charge control terminal Pcl: Communication terminal Pds: Discharge control terminal Pvcc+: Positive terminal Pvcc-: Negative terminal

Claims

1. A lithium-ion battery pack comprising: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, and a communication terminal; a BMS circuit built into the housing and including a control unit which controls charging and discharging of the lithium-ion battery cell; a communication control unit which outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without passing through the BMS circuit; a first relay circuit which receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; a first regulator which supplies power to the control unit; and a second regulator which supplies power to the communication control unit separately from the first regulator.

2. A lithium-ion battery pack comprising: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, a communication terminal, and a control terminal; a BMS circuit built into the housing and including a control unit which controls charging and discharging of the lithium-ion battery cell; a communication control unit which outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without passing through the BMS circuit; a first relay circuit which receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; and a second relay circuit which is connected in parallel to the first relay circuit and receives a second control signal from the control terminal and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal.

3. The lithium-ion battery pack according to claim 2, wherein the second relay circuit is formed of a series circuit in which the drain terminals or source terminals of two n-channel MOSFETs are connected together, and the gate terminals of each n-channel MOSFET are used as the first control terminal and the second control terminal.

4. A charging system comprising: a lithium-ion battery pack; and a charger connectable to the lithium-ion battery pack and having a function of acquiring an OCV of a lithium-ion battery cell, wherein the lithium-ion battery pack comprises: a lithium-ion battery cell; a housing in which the lithium-ion battery cell is built and which has a positive terminal, a negative terminal, a communication terminal, and a control terminal; a BMS circuit built into the housing and including a control unit that controls charging and discharging of the lithium-ion battery cell; a communication control unit that outputs a terminal voltage value of the lithium-ion battery cell to the outside through the communication terminal without passing through the BMS circuit; a first relay circuit that receives a first control signal from the control unit of the BMS circuit and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; and a second relay circuit that is connected in parallel to the first relay circuit and receives a second control signal from the control terminal and conducts or cuts off the power supply to the lithium-ion battery cell through the positive terminal and the negative terminal; and the charger comprises: a first mode in which the second relay circuit is energized through the control terminal based on a terminal voltage value of the lithium-ion battery cell output from the communication control unit, charging at a predetermined current value for a first time, and measuring the terminal voltage value of the lithium-ion battery cell immediately after the first time has elapsed; and a second mode in which, after the first mode has ended, the second relay circuit is interrupted, charging is suspended for a second time, an OCV value of the lithium-ion battery cell immediately after the second time has elapsed, and thereafter the charging system returns to the first mode; and a charging system that estimates a cause of a failure of the lithium-ion battery pack based on the acquired OCV data.

5. The charging system according to claim 4, comprising: an external server having a calculation function for analyzing OCV data of the lithium-ion battery cell; and a communication line connecting the external server and the charger, wherein the charger transmits the acquired multiple OCV data to the external server via the communication line, the external server calculates a degree of deterioration of the lithium-ion battery cell using the calculation function, and then transmits the result to the charger via the communication line, and the charger displays the calculation result of the degree of deterioration.

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