A method for testing the thermal loss of sodium salt batteries during floating charge

Abstract

The present invention relates to a sodium salt battery floating charge heat loss test method, comprising: S1, placing a sodium salt battery pack on a tray in a blast thermostat; S2, connecting a heating plate in the sodium salt battery pack to a heating circuit; S3, connecting a thermocouple in the sodium salt battery pack to a temperature monitoring control circuit; S4, connecting an ammeter in the heating circuit, connecting a voltmeter at both ends of the heating plate, and connecting the ammeter and the voltmeter to a data acquisition instrument; S5, using a heating power supply to heat the sodium salt battery pack for 12-16 hours, and setting the blast thermostat to a constant temperature; S6, after heating is completed, continuously keeping the sodium salt battery pack warm and temperature controlled for 8 hours; recording the voltage and current data collected by the data acquisition instrument, and continuously collecting for 8 hours; S8, calculating the floating charge heat loss power, and completing the test. The sodium salt battery floating charge heat loss test method of the present invention can measure the overall heat loss of the battery pack with high precision and simplicity.

Description

Technical Field

[0001] The invention belongs to the technical field of battery testing and relates to a floating charge heat loss testing method for a sodium salt battery. Background Art

[0002] The operating temperature of sodium salt batteries is 250℃-350℃. In order to meet normal use, the sodium salt batteries need to be wrapped with insulation materials (the whole is called a battery pack). At the same time, there is a heating plate in the battery pack to ensure the temperature inside the battery pack in real time. When the battery pack is working normally, the temperature on the surface of the battery pack is about 15℃ higher than the room temperature, so the surface of the battery pack continuously dissipates heat. The heat dissipation is an important indicator to characterize the thermal insulation performance of the battery pack. It is of great significance to accurately measure the thermal insulation material development of the battery pack and the energy utilization rate of the battery pack. Usually, the heat dissipation performance of the battery pack when the battery pack is neither charged nor discharged is called floating charge heat loss. It is generally believed that the greater the heat dissipation, the more energy is wasted during use and the worse the product performance.

[0003] During the floating charge heat loss test, it is necessary to simulate the use environment of the battery pack. The heating method is the internal heating plate of the battery pack. When the internal temperature of the battery pack is lower than 280°C, the heating plate performs heating. When the temperature is higher than 285°C, the heating stops. Therefore, the temperature inside the battery pack is constantly changing, and the heat dissipation rate also changes dynamically. The BMS battery management system currently used to characterize floating charge heat loss has the problem of poor accuracy. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a method for testing the floating charge heat loss of a sodium salt battery.

[0005] To achieve the above object, the present invention provides a sodium salt battery floating charge heat loss test method, comprising:

[0006] S1. Place the sodium salt battery pack on a tray in a constant temperature box;

[0007] S2, connecting one end of the heating plate in the sodium salt battery pack to the positive electrode of the heating power supply through a wire, and the other end of the heating plate is connected to a solid-state relay, and the solid-state relay is connected to the negative electrode of the heating power supply, thereby forming a heating circuit;

[0008] S3, connecting the thermocouple in the sodium salt battery pack to the temperature controller through a wire, and the temperature controller is connected to the solid-state relay; the temperature controller controls the solid-state relay by monitoring the temperature in the sodium salt battery pack to close or open the heating circuit;

[0009] S4, an ammeter is connected in the heating circuit, two ends of the heating plate are connected to a voltmeter, and the ammeter and the voltmeter are connected to a data acquisition instrument;

[0010] S5. Setting a control trigger temperature of the temperature controller, using the heating power supply to heat the sodium salt battery pack for 12-16 hours, and setting the blast thermostat to a constant temperature;

[0011] S6. When the temperature inside the sodium salt battery pack reaches the control trigger temperature, the heating is completed, and the sodium salt battery pack is kept warm and temperature controlled for 8 hours, so that the internal temperature of the sodium salt battery pack reaches a balanced state;

[0012] S7. When the temperature inside the sodium salt battery pack reaches the control trigger temperature, record the voltage and current data collected by the data acquisition instrument, and continue collecting for 8 hours;

[0013] S8, according to the formula , calculate the heating energy of 8 hours, the heating energy is equal to the heat release energy of 8 hours, calculate the floating charge heat loss power according to the formula P=Q(t) / t, and complete the test, where P represents the floating charge heat loss power, Q(t) represents the heating energy, U represents the voltage collected by the collector, and I represents the current collected by the collector.

[0014] Furthermore, the tray in the blast thermostatic box is a wooden pallet.

[0015] Furthermore, if the sodium salt battery pack is provided with a BMS system, before step S1, the BMS system of the sodium salt battery pack is removed.

[0016] The sodium salt battery floating charge heat loss test method of the present invention can measure the overall heat loss of the battery pack with high precision and simplicity, and can be applied to various tasks such as BMS precision calibration, insulation cotton incoming material inspection, insulation cotton selection, insulation research and development, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The circuit principle diagram of a method for testing heat loss during floating charge of a sodium salt battery according to one embodiment of the present invention is schematically shown.

[0018] The meanings of the symbols in the accompanying drawings are as follows:

[0019] 1. Heating plate; 2. Heating power supply; 3. Solid-state relay; 4. Thermocouple; 5. Temperature controller; 6. Ammeter; 7. Voltmeter; 8. Data acquisition instrument. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0022] Combination Figure 1 As shown, the present invention provides a method for testing the floating charge heat loss of a sodium salt battery, comprising: S1. Placing the sodium salt battery pack on a tray in a blast thermostatic box. To reduce heat conduction, the tray is a wooden pallet. Of course, according to the concept of the present invention, the test of the present invention can also be performed on a sodium salt battery with a BMS system. For this type, the BMS of the sodium salt battery needs to be removed first; S2. Connecting one end of the heating plate 1 in the sodium salt battery pack to the positive electrode of the heating power supply 2 through a wire, and the other end of the heating plate is connected to a solid-state relay 3, and the solid-state relay 3 is connected to the negative electrode of the heating power supply 2, thereby forming a heating circuit; S3. Connecting the thermocouple 4 in the sodium salt battery pack to the temperature controller 5 through a wire, and the temperature controller 5 is connected to the solid-state relay 3; the temperature controller 5 controls the solid-state relay 3 by monitoring the temperature in the sodium salt battery pack to close or disconnect the heating circuit; S 4. Connect an ammeter 6 to the heating circuit, connect two ends of the heating plate 1 to a voltmeter 7, and connect the ammeter 6 and voltmeter 7 to a data acquisition instrument 8; S5. Set the control trigger temperature of the temperature controller 5, use the heating power supply 2 to heat the sodium salt battery pack for 12-16 hours, and set the blast thermostat to a constant temperature; S6. When the temperature inside the sodium salt battery pack reaches the control trigger temperature, complete the heating, and continue to keep the sodium salt battery pack warm for 8 hours, and use the heating circuit to keep the internal temperature of the sodium salt battery pack in a balanced state; S7. When the temperature inside the sodium salt battery pack reaches the set trigger temperature, record the voltage and current data collected by the data acquisition instrument, and continue collecting for 8 hours; S8. According to the formula , calculate the heating energy of 8h, the heating energy is equal to the heat release energy of 8h, calculate the floating charge heat loss power according to the formula P=Q(t) / t, and complete the test, where P represents the floating charge heat loss power, Q(t) represents the heating energy, U represents the voltage collected by the collector, and I represents the current collected by the collector. .

[0023] The method of the present invention is described below by means of specific embodiments:

[0024] Taking a company's sodium salt battery E4815 as an example, the test method of floating charge heat loss is described. The E4815 battery pack contains 126 sodium salt cells, a built-in 600W, 48VDC heater (two circuits in parallel), and three RTD thermocouples. The battery pack is equipped with a BMS and has an automatic temperature control function.

[0025] First, remove the sodium salt battery pack BMS, and then place it in a blast thermostatic box. Note that the battery pack tray should not be a metal tray to reduce heat conduction. Two 50mm*50mm*500mm wooden sticks can be used as the sodium salt battery bottom tray;

[0026] according to Figure 1 The wiring is done according to the electrical schematic diagram. The two circuits of the heating plate are connected in parallel and heated with a 48VDC heating power supply. The power of the heating plate is 600W. This circuit harness is connected with 2.5mm2 or 4mm2 insulated copper cable. The temperature controller uses a 12VDC power supply or a 220VAC power supply with low power, and the cable can be a 0.5mm2 copper cable. There are 3 RTD thermocouples in the battery pack, which are connected to the temperature controller respectively. The temperature controller detects that the temperature in the battery pack is lower than 285℃, controls the solid-state relay, closes the heating circuit, and performs heating; when the temperature is higher than 285℃, the heating circuit is disconnected and heating is stopped. Set the trigger temperature of the temperature controller to 285℃ (different temperature values ​​can be set). Use this circuit to heat the battery pack. It takes about 12~16 hours to heat it. At the same time, close the door of the constant temperature box and set the temperature of the constant temperature box to 25℃. The constant temperature box is always in a constant temperature state. After heating, continue to keep the battery pack warm for 8 hours to make the internal temperature of the battery pack reach a balanced state. Record the current, voltage, and time. Collect data continuously for 8 hours. Remove abnormal points in the data and use the formula , the heating energy in the 8h interval can be calculated, heating energy = heat release energy, and the floating charge heat loss power is P = Q (t) / t.

[0027] The sodium salt battery floating charge heat loss test method of the present invention uses conventional, simple and technologically mature devices such as ammeters and voltmeters to complete data acquisition to realize the test and calculation of floating charge heat loss. There is no need to develop special instruments, such as special BMS systems, which is conducive to reducing costs. At the same time, the accuracy of the test method of the present invention is much higher than that of the BMS system. The error rate of the BMS system is about 5%-8%, and the present invention uses ammeters and voltmeters for testing, and the error rate can be controlled below 0.5%, greatly improving the test accuracy. Therefore, the method of the present invention can be used for BMS calibration, BMS incoming material inspection, selection of thermal insulation cotton, research and development of thermal insulation design, calculation of battery pack standby time, configuration of battery capacity according to application conditions, and the like.

[0028] The above is only one embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for testing the floating charge heat loss of a sodium salt battery, comprising: S1. Place the sodium salt battery pack on a tray in a constant temperature box; S2, connecting one end of the heating plate in the sodium salt battery pack to the positive electrode of the heating power supply through a wire, and the other end of the heating plate is connected to a solid-state relay, and the solid-state relay is connected to the negative electrode of the heating power supply, thereby forming a heating circuit; S3, connecting the thermocouple in the sodium salt battery pack to the temperature controller through a wire, and the temperature controller is connected to the solid-state relay; the temperature controller controls the solid-state relay by monitoring the temperature in the sodium salt battery pack to close or open the heating circuit; S4, an ammeter is connected in the heating circuit, two ends of the heating plate are connected to a voltmeter, and the ammeter and the voltmeter are connected to a data acquisition instrument; S5. Setting the control trigger temperature of the temperature controller, using the heating power supply to heat the sodium salt battery pack for 12-16 hours, and setting the blast thermostat to a constant temperature; S6. When the temperature inside the sodium salt battery pack reaches the control trigger temperature, the heating is completed, and the sodium salt battery pack is kept warm and temperature controlled for 8 hours, so that the internal temperature of the sodium salt battery pack reaches a balanced state; S7. When the temperature inside the sodium salt battery pack reaches the control trigger temperature, record the voltage and current data collected by the data acquisition instrument, and continue collecting for 8 hours; S8, according to the formula , calculate the heating energy of 8h, the heating energy is equal to the heat release energy of 8h, and then calculate the floating charge heat loss power according to the formula P=Q(t) / t to complete the test, where P represents the floating charge heat loss power, Q(t) represents the heating energy, U represents the voltage collected by the collector, and I represents the current collected by the collector.

2. The sodium salt battery floating charge heat loss test method according to claim 1, characterized in that: The tray in the blast thermostatic box is a wooden tray.

3. The sodium salt battery floating charge heat loss test method according to claim 1, characterized in that: If the sodium salt battery pack is equipped with a BMS system, the BMS system of the sodium salt battery pack is removed before step S1.

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