Short-circuit current testing device of lithium battery

Abstract

The utility model discloses a short-circuit current testing device of a lithium battery, which comprises a relay, one end of a contact of the relay is electrically connected with a diverter, the other end of the contact is electrically connected with a cathode of the lithium battery, an anode of the lithium battery is electrically connected with the diverter, a coil of the relay is connected with a time controller in parallel, and the time controller is electrically connected with the diverter. The shunt is connected in parallel with an oscilloscope. According to the device, the short circuit process of the battery is controlled through the relay, physical invasion of the battery is not needed, and damage to the internal structure of the battery and potential thermal runaway risks caused by mechanical operation are avoided. The automatic control of the device reduces manual operation errors and ensures the consistency of test conditions each time, so that the repeatability and reliability of test results are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of battery safety test, concretely relates to a short circuit current testing device of lithium battery. BACKGROUND

[0002] As an important part of new energy storage technology, the safety of lithium iron phosphate battery has always been a key concern in lithium battery research and application. When the battery has safety problems, the main performance is abnormal temperature rise, which may even cause thermal runaway and safety accidents. Therefore, the safety of the battery is closely related to temperature control. In order to ensure the safety of the battery, the standard test method usually includes overcharge, overdischarge, puncture, extrusion, drop, heating and short circuit and other test items.

[0003] At present, China has formulated relevant standards to regulate the safety of battery short circuit test. For example, GB / T36276-2018 specifies the battery short circuit test method, which requires external short circuit of the positive and negative poles of the battery module for 10 minutes. The battery should not catch fire or explode during the test process. In the prior art, the needle puncture method is used for battery short circuit test. This method vertically punctures the preset position of the battery pole plate with a needle, and carries out charging and discharging operation on the battery in the state of the needle staying, so as to obtain the short circuit resistance and the change value of the battery temperature, and then calculate the internal short circuit current.

[0004] However, the inconsistency of the needle puncture position and depth will cause significant difference in the short circuit current value, affecting the accuracy and reliability of the test results. UTILITY MODEL CONTENTS

[0005] The utility model provides a short circuit current testing device of lithium battery, solves the problem of low accuracy in the battery short circuit test process of prior art.

[0006] In order to solve the above technical problems, the utility model provides a short circuit current testing device of lithium battery, which comprises: a relay, one end of the contact of the relay is electrically connected with a shunt, the other end of the contact is electrically connected with the negative pole of the lithium battery, the positive pole of the lithium battery is electrically connected with the shunt, a time controller is connected in parallel on the coil of the relay, and an oscilloscope is connected in parallel on the shunt.

[0007] Preferably, the time controller comprises a time control circuit board and four control buttons, the time control circuit board is electrically connected with the four control buttons, one end of the time control circuit board is electrically connected with the input interface of the time controller, and the other end is electrically connected with the output interface of the time controller.

[0008] Preferably, the first button in the control button is a cancel / resume button; the second button is a time setting / calibration button; the third button is a timing button; and the fourth button is an automatic / manual button.

[0009] Preferably, the time controller is further provided with a display screen.

[0010] Preferably, the relay is an electromagnetic relay.

[0011] Preferably, the surface of the lithium battery is provided with a temperature sensor.

[0012] Preferably, the temperature sensor is provided with an alarm device.

[0013] Preferably, the short-circuit current testing device further comprises an overcurrent protection device connected in series with the lithium battery.

[0014] The utility model discloses a beneficial effect at least includes: through the oscilloscope parallelly connected on the shunt, can capture the voltage pulse signal of battery short circuit instantaneousness in real time, and then combining the voltage-current conversion relation of shunt, can accurately calculate the peak value and dynamic change of battery short circuit current, and the device is suitable for various types of lithium battery, has extensive applicability, can adjust according to different test standards or research demand, for example changes short circuit time or current measurement range, to satisfy the diversified test requirement. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the device structure schematic drawing of the utility model embodiment;

[0016] Figure 2 It is the internal structure schematic drawing of time controller in the utility model embodiment;

[0017] Figure 3 It is the external structure schematic drawing of time controller in the utility model embodiment;

[0018] Figure 4 It is the circuit schematic drawing of the utility model embodiment measurement battery internal resistance;

[0019] Figure 5 It is the circuit schematic drawing of the utility model embodiment measurement circuit internal resistance.

[0020] In the drawing: 1 - relay;11 - relay contact;12 - relay coil;2 - shunt;3 - lithium battery;4 - time controller;41 - time control circuit board;42 - control button;43 - input interface;44 - output interface;45 - display screen;5 - oscilloscope;6 - temperature sensor;7 - alarm device;8 - overcurrent protection device. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0022] As shown in the figure, Figure 1 The utility model embodiment provides a short circuit current testing device of lithium battery, include: relay 1, the contact 11 of relay 1 is connected with shunt 2 electricity, the other end of contact 11 is connected with the negative pole of lithium battery 3 electricity, the positive pole of lithium battery 3 is connected with shunt 2 electricity, the coil 12 of relay 1 is parallelly connected with time controller 4, and shunt 2 is parallelly connected with oscilloscope 5.

[0023] Specifically, the device of the utility model embodiment controls the short circuit process through the relay, without physical invasion to the battery, avoiding the damage of the internal structure of the battery and the potential thermal runaway risk caused by mechanical operation.

[0024] The time controller can accurately set the short circuit time, strictly limit the duration of the short circuit process, and prevent the battery from overheating, fire or explosion caused by long-time short circuit, thereby protecting the safety of the test personnel. The automation control of the device reduces the human operation error, ensures the consistency of each test condition, and improves the repeatability and reliability of the test results.

[0025] When the direct current exceeds the range of the ordinary ammeter, the shunt can be used for measurement. The shunt is an electronic component, mainly used for expanding the current range and measuring direct current. The principle of the shunt is to use the voltage generated by the resistance when passing through the direct current to realize the measurement of the current. The use of the shunt can withstand a larger short circuit current, avoid the damage of the current to the test equipment and the battery itself, and further improve the safety of the test.

[0026] By connecting the oscilloscope in parallel with the shunt, the voltage pulse signal at the moment of short circuit can be captured in real time. Combined with the voltage-current conversion relationship of the shunt, the peak value and dynamic change of the short circuit current can be accurately calculated.

[0027] At the same time, the oscilloscope has data storage and playback functions, which is convenient for detailed analysis of the voltage and current waveforms in the short circuit process, and provides accurate data support for battery safety performance evaluation.

[0028] As shown in the figure, Figure 2As shown, the time controller 4 includes a time control circuit board 41 and four control buttons 42. The time control circuit board 41 is electrically connected to the four control buttons 42. One end of the time control circuit board 41 is electrically connected to the input interface 43 of the time controller 4, and the other end is electrically connected to the output interface 44 of the time controller 4.

[0029] Specifically, the time control circuit board 41 is the core component of the time controller 4, which can accurately control the duration of the short circuit. Through circuit design, it can achieve precise timing from milliseconds to seconds, ensuring the accuracy of the short circuit time. This precise time control is crucial for preventing the battery from overheating or damaging due to long-term short circuit, and also ensures the reliability of the test results.

[0030] The first button 421 in the control button 42 is a cancel / resume button; the second button 422 is a time setting button; the third button 423 is a timing button; and the fourth button 424 is an automatic / manual button. The four control buttons 42 are electrically connected to the time control circuit board, providing an intuitive and easy-to-operate interface for the operator. The operator can easily set the short circuit time through these buttons without complex menu operations or external computer control. This design reduces the difficulty of operation, so that even non-professionals can quickly get started, improving test efficiency.

[0031] As shown in Figure 3 The time controller 4 is also provided with a display screen 45.

[0032] Specifically, the display screen 45 can display the current set short circuit time, remaining time or current state, etc. in real time. This intuitive visual feedback allows the operator to clearly understand the real-time progress of the test process, avoiding misoperation or test failure due to unclear information.

[0033] The relay 1 is an electromagnetic relay.

[0034] Specifically, the electromagnetic relay can control a larger current or high-power circuit through a smaller control current or voltage. In the lithium battery short circuit test, a low-power control signal can be used to trigger a high-current short circuit operation, improving the safety and flexibility of the test. And the contact capacity of the electromagnetic relay is larger, which can withstand the high current impact that may occur during the short circuit test, which makes the relay able to safely carry the short circuit current in a short time without being damaged by overload.

[0035] The surface of the lithium battery 3 is provided with a temperature sensor 6. The temperature sensor 6 is provided with an alarm device 7.

[0036] Specifically, during the short circuit process, the temperature of the battery can rise rapidly. The temperature of the battery can be monitored in real time through the temperature sensor. Once the temperature exceeds the safety threshold, the short circuit circuit is immediately cut off, and an alarm is issued to remind the operator.

[0037] The short-circuit current testing device further comprises an overcurrent protection device 8 connected in series with the lithium battery 3.

[0038] Specifically, although the device can accurately control the short-circuit time through the time controller, in extreme cases such as time controller failure or accidents, the short-circuit time may still be too long, thereby causing the battery to overheat or even catch fire. Therefore, an overcurrent protection device is arranged in the circuit, which immediately cuts off the circuit when the current exceeds the preset threshold, further reducing the safety risk.

[0039] The internal resistance test of the battery using the device comprises the following steps:

[0040] 1. Preparation stage

[0041] Prepare the lithium iron phosphate battery to be tested, the internal resistance tester, the wire, the shunt, the relay, the time controller, and the oscilloscope, and other equipment. The specification of the lithium iron phosphate battery of the utility model is 3.2V / 280Ah.

[0042] 2. Test the internal resistance of the battery

[0043] As shown in Figure 4 , the positive and negative test lines of the internal resistance tester are connected to the positive and negative electrodes of the lithium iron phosphate battery to be tested, respectively. Start the internal resistance tester, measure the internal resistance value of the battery, and record the value as R 内 .

[0044] 3. Test the whole loop resistance value

[0045] As shown in Figure 5 , one end of the internal resistance tester is connected to one contact of the relay through the wire, and the other end is connected to one end of the shunt through the wire; the other end of the shunt is connected to the other contact of the relay.

[0046] Parallel the output 12V power supply of the time controller to the coil of the relay, close the relay contact, and make the whole loop connected.

[0047] Measure the resistance value of the whole loop through the internal resistance tester, and record the value as R 线 .

[0048] 4. Prepare for short-circuit test

[0049] Connect the positive terminal of the lithium iron phosphate battery under test to one end of the relay contact via a wire. Connect the other end of the relay contact to one end of the shunt via a wire. Connect the other end of the shunt to the negative terminal of the battery. Connect the oscilloscope in parallel across the shunt for subsequent short-circuit current measurement.

[0050] 5. Short-circuit test and data acquisition

[0051] Set the desired short-circuit time using the timer. Close the relay to momentarily short-circuit the battery. Capture the maximum voltage pulse signal at the moment of short-circuit using an oscilloscope and record the voltage value U.

[0052] 6. Calculate the short-circuit current.

[0053] According to Ohm's law, through formula I Man =U / (R) 内 +R 线 The short-circuit current I was calculated. Man Record the calculated short-circuit current value for subsequent analysis and evaluation.

[0054] This invention provides a short-circuit current testing device for lithium batteries, which can control the short-circuit time of the battery cell, effectively protecting the battery cell and allowing the battery to be used again after short-circuit testing. Simultaneously, it can precisely control the current magnitude during battery short-circuit testing, ensuring the safety of testing personnel.

[0055] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. Only preferred embodiments of the present invention are shown, and the descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. As long as the combination of these technical features does not contradict each other, it should be considered as within the scope of this specification.

[0056] It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

Claims

1. A short-circuit current testing device for lithium batteries, characterized in that, include: A relay (1) is provided, one end of the contact (11) of the relay (1) is electrically connected to the shunt (2), the other end of the contact (11) is electrically connected to the negative terminal of the lithium battery (3), the positive terminal of the lithium battery (3) is electrically connected to the shunt (2), a time controller (4) is connected in parallel to the coil (12) of the relay (1), and an oscilloscope (5) is connected in parallel to the shunt (2).

2. The short-circuit current testing device for lithium batteries according to claim 1, characterized in that: The time controller (4) includes a time control circuit board (41) and four control buttons (42). The time control circuit board (41) and the four control buttons (42) are electrically connected. One end of the time control circuit board (41) is electrically connected to the input interface (43) of the time controller (4), and the other end is electrically connected to the output interface (44) of the time controller (4).

3. The short-circuit current testing device for lithium batteries according to claim 2, characterized in that: The first button (421) of the control buttons (42) is the cancel / restore button; the second button (422) is the time / minute setting button; the third button (423) is the timer button; and the fourth button (424) is the automatic / manual button.

4. The short-circuit current testing device for lithium batteries according to claim 2, characterized in that: The time controller (4) is also equipped with a display screen (45).

5. The short-circuit current testing device for lithium batteries according to claim 1, characterized in that: The relay (1) is an electromagnetic relay.

6. The short-circuit current testing device for lithium batteries according to claim 1, characterized in that: A temperature sensor (6) is provided on the surface of the lithium battery (3).

7. The short-circuit current testing device for lithium batteries according to claim 6, characterized in that: An alarm device (7) is provided on the temperature sensor (6).

8. The short-circuit current testing device for lithium batteries according to claim 1, characterized in that: The short-circuit current testing device also includes an overcurrent protection device (8), which is connected in series with the lithium battery (3).

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